WO2023222244A1

WO2023222244A1 - Fiber-reinforced composite material, component, vehicle and method for manufacturing a fiber-reinforced composite material

Info

Publication number: WO2023222244A1
Application number: PCT/EP2022/063814
Authority: WO
Inventors: Andrea Pretzler; Johannes Steindl; Patrick DOMNANICH
Original assignee: F. List Gmbh
Priority date: 2022-05-20
Filing date: 2022-05-20
Publication date: 2023-11-23

Abstract

The invention relates to a fiber-reinforced composite material including at least one matrix made of a biobased material and a plurality of natural fibers which are at least partially embedded within the matrix. The matrix includes at least one flame retardant arranged at least partially within the matrix. The natural fibers include at least one flame retardant arranged in at least a section of the natural fibers. The invention also relates to a component, preferably a paneling element, for use in an interior of a vehicle. The invention further relates to a vehicle and a method for manufacturing a fiber- reinforced composite material.

Description

Fiber-reinforced composite material, component, vehicle and method for manufacturing a fiber-reinforced composite material

Providing a comfortable and/or appealing environment in an interior of a vehicle may be considered to be a relatively important aspect in the configuration of the vehicle, in particular for customer satisfaction and/or customer appeal. In particular, many vehicles, such as aircrafts, watercrafts and/or land-bound vehicles, travel across relatively long distances such that the occupants of the respective vehicles spend a relatively large amount of time in the interior of the vehicles. Moreover, many owners of vehicles may have a desire to personalize the interior of their vehicle(s), which may be achieved by providing customized decorative articles in the interior of their respective vehicle.

Hence, configuring the interior of vehicles is considered to be a relatively important aspect. For instance, the choice of materials used in the interior may be one key aspect to consider when configuring the respective vehicle. In general, the material(s) should generally appeal to the customers and/or occupants of the vehicle(s). For one, many customers and/or occupants of the respective vehicles value material(s) which are aesthetically appealing and/or do not have health-adverse effects. Moreover, many materials may be generally off-putting and/or averse to many customers and/or occupants of the respective vehicles, such as materials which emit an odor, e.g., a particularly strong odor, and/or are easily damages.

Moreover, it is generally required that the material(s) are suited for the operating environment(s) of the concerned vehicle, e.g., such that the material(s) do(es) not pose a hazard, e.g., a fire hazard. Thus, for instance, materials used in aircrafts, in particular private and/or commercial aircrafts, must generally, at least in most countries, meet certain standards to be allowable for use.

Moreover, many people nowadays are environmentally aware. Thus, many customer(s) and/or occupants of the respective vehicles may prefer materials which are aligned with their environmental awareness and/or which are less environmentally detrimental than other materials. However, the materials known from the prior art have several drawbacks. For instance, many materials know from the prior art are not suited for various operating environments of vehicle, in particular of aircrafts and/or watercrafts.

Moreover, many materials known from the prior art may have health-adverse effects and/or may not be environmentally friendly. In addition, many materials, in particular alternative materials, in an attempt to be more environmentally friendly and/or have less health-adverse effects, often have negative effects on the suitability of the concerned material(s) with regard to various operating environments of one or more vehicles and/or may negatively affect the sturdiness and/or durability of the concerned material(s).

Thus, based on the prior art, there remains a need to improve the materials, e.g., by improving or eliminating one or more drawbacks of the materials know from the prior art, e.g., one or more of the above-identified drawbacks.

It is therefore an object of the present invention to provide an improved material, in particular for use in vehicles, in particular aircrafts.

This object is achieved by a fiber-reinforced composite material as defined by the features of claim 1. Preferred embodiments are defined by the features of the respective dependent claims.

The composite material may include at least one matrix made of a biobased material and a plurality of natural fibers which are at least partially embedded within the matrix. The matrix may include at least one flame retardant arranged at least partially within the matrix. The natural fibers may include at least one flame retardant arranged in at least a section of the natural fibers. The matrix may include one or more curable components, e.g., one or more thermosets.

Thus, providing a composite material having a biobased matrix and natural fibers may provide an environmentally friendly material made at least partially of renewable components. This may reduce the ecological footprint of the composite material compared with materials known from the prior art. This may also reduce or eliminate one or more health-adverse effects of the composite material, e.g., by omitting or at least reducing the amount of synthetic components, such as one or more chemical products included in the matrix and/or the fibers, in the composite material. A wide range of biobased materials for the matrix and natural fibers may be selected, e.g., in accordance with the requirements, desires and/or demands for a particular application and/or purpose of the composite material.

Biobased materials and natural fibers, however, may often be more flammable than synthetic fibers and non-biobased materials, respectively, thus making natural fibers generally less suitable for environments in which flammability properties, such as in many powered vehicles, e.g., aircrafts, i.e., private and/or commercial aircrafts, and/or watercrafts, must and/or should be considered. Thus, the inventors have found that by including at least one flame retardant at least partially within the matrix and at least one flame retardant in at least a section of the natural fibers, in particular when applied separately to the matrix and the natural fibers, in particular before the fibers have been at least embedded in the matrix, the advantages of the biobased material and the natural fibers may be employed, e.g., providing a smaller ecological footprint, while achieving suitable flame retardant properties of the composite material for use in most operating environments of most vehicles, e.g., aircrafts, i.e., private and/or commercial aircrafts, and/or watercrafts. In particular, the composite material described herein may be suitable for use in aerospace vehicles, in particular for aircrafts, e.g., private and/or commercial aircrafts, and/or spacecrafts.

The composite material may be configured as a prepreg, e.g., as one or more sheets and/or one or more strips of prepreg. In the prepreg, the matrix, more specifically one or more materials of the matrix, is preferably partially cured, e.g., to allow easier handling of the prepreg, e.g., to form or mould one or more parts using the prepregs. Such a partially cured state or intermediate state of cure of the matrix is often referred to as a B-stage of the matrix. Thus, forthe B-stage of the matrix, a cross-linking reaction, i.e., the curing or hardening phase, of the matrix has been initiated, but has not been completed. Further explanation of a B-stage of a matrix is provided in "Phenolic Resins: A Century of Progress" by Louis Pilato, Heidelberg 2010 (ISBN: 978-3-642-04714-5), page 95) which is herewith incorporated by reference. To prevent further curing of the matrix, prepregs are often stored in cooled areas since heat may initiate and/or accelerate curing of the matrix. To prevent further curing, prepregs are often placed in a freezer at 0 °F. In a frozen state, the matrix of the prepreg material may remain in the B-stage. Further curing of the matrix usually starts when the material is removed from the freezer and/or heated.

In an A-stage of the prepreg, one or more components of the matrix, e.g., a base material and a hardener, may have been mixed but curing of the matrix may not have started. Thus, the matrix may be substantially liquid in the A-stage. In a C-stage of the prepreg, the matrix may be fully cured.

The matrix may be configured to cure, e.g., fully cure, at room temperature. Alternatively, the matrix may be configured such that the matrix must be heated to partially and/or fully cure. Alternatively, or additionally, the matrix may be configured to be cure based on one or more chemical reactions, such as in the case of a thermoset which may be included in the matrix of the composite material described herein. Optionally, a pressure, preferably a pressure which is greater than an ambient pressure, may be applied to at least a section of the composite material, e.g., the prepreg, before and/or during curing the composite material, preferably while heating the composite material at a temperature which is above an ambient temperature. This may facilitate a distribution and/or a flow of the matrix. In particular, a viscosity of the matrix may first drop as the temperature is increased and may then increase in viscosity as the curing proceeds. Thus, applying a pressure to at least a section of the composite material may increase the distribution and/or the flow of the matrix, e.g., to counteract an increase in the viscosity of the matrix as the curing proceeds. Applying a pressure to at least a section of the composite material may also facilitate joining and/or adhesion of one or more composite material layers, e.g., prepreg layers, to each other and/or to one or more further composite material layers, e.g., prepreg layers, e.g., adjacent prepreg layers, and/or to further components of the final composite, such as to one or more core layers.

The prepreg may be configured to be moulded to a one or more components for an interior of a vehicle, such as one or more paneling elements for the interior of a vehicle. Components which are moulded purely from composite materials, such the as the composite material described herein, may have a relatively high tensile strength, e.g., at least in a direction along the fibers.

Alternatively, or additionally, the composite material may be configured for use in sandwich- structured composites, e.g., as one or more layers of such sandwich-structured composites. The sandwich-structured composite may include one or more layers, preferably at least two layers, preferably at least two outer layers, which sandwich at least one core element. The core element may be at least partially made of a foam, a honeycomb (e.g. including aramide paper or PLA), cork, balsa wood, preferably recycled balsa wood, kiri wood, preferably recycled kiri wood, sea-recovered plastic (e.g. polycarbonate) and/or one or more similar materials. The foam may be made from renewable resources or substantially from recycled plastic, such as PET or PC. The core element(s) may or may not include flame retardant(s) and/or flame treatment(s). The sandwich may be configured to be symmetrical or asymmetrical. For instance, an asymmetrical construction may be void of composite material layers, e.g., prepreg layers, on one side of a core of the asymmetrically constructed sandwich.

The natural fibers may extend substantially unidirectionally within the matrix. Alternatively, the natural fibers may extend in different directions. For instance, a first set of the natural fibers may extend in a first direction and a second set of the natural fibers may extend in a second direction which is different from the first direction.

Preferably, a plurality of fibers provided in the composite material, preferably including a portion of at least the natural fibers, are configured as a crossed-fiber construction, preferably as a woven mesh, a web, a fleece, a knitting and/or a textile.

The term "biobased matrix", which is sometimes also referred to as "biogenic material", refers to a matrix which is at least partially derived from plants, e.g., sugar cane, and other renewable agricultural, marine, and forestry materials, such as organisms. The matrix may include one or more components, e.g., one or more additives, which are not derived from plants and other renewable agricultural, marine, and forestry materials, such as one or more synthetic components. Preferably, a relatively large proportion of the matrix, e.g., 60 wt% to 80 wt% of a total weight of the matrix, may be biobased.

The term "natural fibers" refers to fibers which are obtained from geological processes, such as mineral sources, and/or from the bodies of plants and/or animals. In other words, the term "natural fibers" includes all fibers which occur naturally and/or are derived from natural sources, e.g., including fibers made from stone or stone wool. Fibers which are derived from natural sources, but which are regenerated, precipitated, and/or treated, such as semisynthetic fibers, e.g., rayon (viscose), are also considered to be natural fibers within the context of the present disclosure.

Preferably, the natural fibers include natural organic fibers and/or natural inorganic fibers. The term "organic" refers to matter, e.g., the fibers, which includes carbon (C). For instance, organic matter may contain carbon (C) and hydrogen (H). Natural organic fibers may be plantbased and/or animal-based. The term "inorganic" refers to matter, e.g., the fibers, which contain no, or very little, carbon. The term "inorganic" includes carbon fibers. Natural inorganic fibers may be mineralic/mineral-based, i.e., mineral fibers, such as wollastonite or basalt fibers. Preferably, a combination of natural organic fibers and/or natural inorganic fibers may be chosen according to the requirements, desires and/or demands for a particular application or purpose of the composite material. For instance, one or more first natural organic fibers and/or natural inorganic fibers provided in the composite material may compensate adverse effects of one or more second natural organic fibers and/or natural inorganic fibers provided in the composite material. Alternatively, or additionally, one or more first natural organic fibers and/or natural inorganic fibers provided in the composite material may enhance one or more effects and/or advantages of one or more second natural organic fibers and/or natural inorganic fibers provided in the composite material.

The term "synthetic", e.g., as in synthetic fibers, refers to non-natural matter, e.g., non-natural fibers. In other words, synthetic matter, such as synthetic fibers, refers to matter which is not obtained from geological processes, such as mineral sources, and/or from the bodies of plants and/or animals. Instead, synthetic matter is man-made.

Preferably, the natural fibers include plant-based fibers. Preferably, the natural fibers only include plant-based fibers.

The composite material may include not only natural fibers. The composite material may also include one or more further types of fibers, which are not natural. For instance, the composite may also include a plurality of synthetic fibers, such as carbon fibers, e.g., as additives. Alternatively, or additionally, the composite material may include mineral fibers which may be of natural origin, i.e., natural fibers, or synthetic origin, i.e., synthetic fibers. The composite material may include one or more of the following mineral fibers: glass fibers, carbon fibers, basalt fibers, other inorganic mineral fibers and ceramic fibers.

Preferably, the composite material includes one or more of the following: a plurality of natural organic fibers, a plurality of natural inorganic fibers, a plurality of synthetic organic fibers and a plurality of synthetic inorganic fibers.

The term "flame retardant" refers to one or more active flame retardant compounds. The one or more active flame retardant compounds may be included in a formulation which also include one or more additives, e.g., which may facilitate penetration of the flame retardant into the natural fibers, e.g., as wetting agents, and/or which facilitate a production process, e.g., antimicrobials which may inhibit deterioration of the liquid flame retardant solution used for impregnating the natural fibers. However, the term "flame retardant", within the context of the present disclosure, refers to the active flame retardant compounds, i.e., not including additives.

Providing a composite material including inorganic and/or carbon fibers, in particular having at least a certain proportion of inorganic and/or carbon fibers with respect to all fibers included in the composite material, may increase the suitability of the composite material for flammable environments, such as in many vehicles, in particular aircrafts, compared with a configuration in which the composite material includes only non-mineralic natural fibers, i.e., without mineral and/or carbon fibers. Moreover, combining natural fibers and mineral and/or carbon fibers, preferably non-natural mineral fibers, in the composite material may provide the composite material with a relatively high mechanical strength. Preferably, the natural fibers included in the composite material may account for at least 30 wt%, preferably 30 wt% to 80 wt%, more preferably 40 wt% to 60 wt%, of a total weight of all fibers provided in the composite material. The inventors have found that such a composite material surprisingly passes the heat release rate (OSU) test and/or the low spread of flame test according to IMO 2010 FTPC Part 5 (referred to in the Maritime Equipment Directive 2014/90/EU of July 23^rd 2014 for class 3.18a).

Preferably, the natural fibers of the composite material, preferably within one layer of prepreg, if the composite material is configured as a prepreg, have an area weight with respect to an area of the composite material, preferably of one layer of prepreg, from 100 g/m2 to 300 g/m2, more preferably from 120 g/m2 to 270 g/m2, more preferably from 180 g/m2 to 220 g/m2.

The area weight WA, sometimes also referred to as area density or areal density, may be determined by determining a mass m, for instance in kilograms (kg), of the natural fibers provided in the composite material. The determined mass m is divided by the area A of the composite material, when the composite material is spread out on a flat surface in a single layer, instance in square centimeters (cm2). As a result, the area weight defines the mass of the natural fibers provided in the composite material per unit area of the composite material in accordance with equation 1 below.

WA = m/A (equation 1)

The flame retardant included in the matrix and the flame retardant included in the natural fibers may be the same flame retardant, e.g., the same type of flame retardant and/or having the same composition. Alternatively, one or more first types of flame retardants, e.g., having one or more first compositions, may be provided for the matrix and one or more second types of flame retardants, e.g., having one or more second compositions, may be provided for the natural fibers, the one or more first types of flame retardants differing from the one or more second compositions, e.g., in their composition(s). A plurality of flame retardants may be used forthe matrix and a plurality of flame retardants may be used for the natural fibers. The flame retardants used for the matrix and the flame retardants used for the natural fibers may partially overlap. In other words, some of the flame retardants used for the matrix and for the natural fibers are the same, e.g., are the same type(s) and/or have the same composition(s).

The inventors have found that the flame retardant effects provided by the flame retardant(s) are particularly high and/or effective, if the natural fibers are first treated with the flame retardant(s) before being embedded in the matrix. Thus, the natural fibers may be soaked in, e.g., highly, saturated with, flame retardant(s). This may provide a relatively high concentration of flame retardant in the natural fibers, which may increase the flame retardant properties of the composite material, e.g., compared with applying the flame retardant(s) after the natural fibers have been embedded in the matrix and/or applying the flame retardant(s) and the matrix simultaneously to the natural fibers, e.g., by applying a matrix which includes a flame retardant therein to the natural fibers, i.e., without previously treated the natural fibers with flame retardant. Moreover, this may allow the flame retardant to penetrate further into the natural fibers and/or may result in a more even distribution of flame retardant in the natural fibers. In addition, this may provide a relatively high degree of flame protection such that the composite material may still meet the requirements which are demanded for use in aircrafts, for both private and commercial air travel, even if one or more further elements, such as one or more coatings, e.g., one or more decorative coatings, e.g., a paint and/or lacquer, are added to the composite material and/or a component made at least partially from the composite material, such as a moulded part, which is generally detrimental for flame protection qualities. This may increase the flexibility in configuring the composite material and/or a component made at least partially from the composite material, such as a moulded part, e.g., for aesthetic reasons, e.g., by enabling the use of a wide range of further elements, e.g., decorative elements, such coatings, while maintaining the necessary flame protection qualities.

The flame retardant included in the matrix may be dissolved in the matrix. Alternatively, the flame retardant included in the matrix may be dispersed in the matrix.

Preferably, the flame retardant arranged in at least a section of the natural fibers has been applied to at least a portion of the natural fibers, before the natural fibers have been embedded at least partially in the matrix. As discussed above, treating the natural fibers with flame retardant before being embedded in the matrix may increase the flame retardant effects provided by the flame retardant(s). The natural fibers may be soaked in, e.g., highly saturated with, flame retardant(s). The flame retardant may be provided in or applied to at least an organic portion, preferably the natural organic portion, of the fibers provided in the composite material, in particular if the composite material includes natural inorganic and/or synthetic/non-natural fibers as well. Thus, the flame retardant may penetrate and/or saturate at least the organic fibers, preferably all of the natural fibers, provided in the composite material. It has been found that flame retardants may have a relatively low effect on inorganic fibers and/or non-natural fibers. Thus, by omitting the flame retardant from the inorganic and/or non-natural fibers, the flame retardant may be used resourcefully in the composite material. This may also limit any adverse effects the flame retardant may have on the composite material, such as odor. Moreover, for instance, providing too much flame retardant may weaken the composite material and/or reduce the adhesion properties of the natural fibers to or in the matrix and/or may decrease flame retardancy due to potential delamination of the composite material. Thus, limiting the flame retardant to the components which provide the greatest flame retardants effects, or at least flame retardants effects which outweigh negative effects of the flame retardant on the composite, such as the disadvantages described above, may strike a balance between flame retardants effects and adverse effects caused by the flame retardant(s).

Preferably, the natural fibers include viscose fibers, preferably only viscose fibers. Specific types of viscose fibers are sometimes referred to as rayon fibers.

Preferably, the natural fibers include one or more of the following: viscose fibers, flax fibers, hemp fibers, bagasse fibers, bamboo fibers, kenaf fibers, jute fibers, ramie fibers, abaca fibers, sisal fibers, coir fibers, oil palm fibers, pineapple fibers and curaua fibers. As discussed at the beginning, a wide range of natural fibers may be selected, e.g., in accordance with the requirements, desires and/or demands for a particular application or purpose of the composite material.

Preferably, the natural fibers include flax fibers and/or viscose fibers, preferably only flax fibers and/or viscose fibers. The inventors have found that flax fibers and/or viscose fibers may work particularly well with bio-based matrices, particularly well with one or more particular types of bio-based matrices, in particular furan resin. For instance, the flax fibers may have a relatively high adherence to or within the matrix compared with other fibers, particularly natural fibers. For instance, this may allow further additives which may promote adhesion of the natural fibers to or within the matrix, such as bonding agents, to be omitted.

Alternatively, or additionally, a relatively high adherence of the fibers, in particularthe natural fibers, within the matrix may be achieved by providing the fibers, particularly the natural fibers, with at least a certain degree or threshold of surface energy. Increasing the surface energy of fibers, particularly natural fibers, e.g., by choosing fibers, particularly natural fibers, intrinsically having a relative high surface energy and/or by modifying and/or treating the fibers, particularly the natural fibers, in one or more modification steps and/or treatment steps. Modifying and/or treating the fibers/natural fibers may be achieved by physical, e.g., mechanical, and/or chemical methods.

For instance, pre-impregnating the fibers/natural fibers with a flame retardant, i.e., before embedding the fibers/natural fibers in the matrix, may increase the total surface energy of the fibers/natural fibers, e.g., by increasing the disperse proportion, or disperse component, of the surface energy of the fibers/natural fibers. An increase in total surface energy may be determined and/or varied by selecting and/or varying the chemical flame retardant molecule(s) and/or by selecting and/or varying the respective concentration(s) of the flame retardant(s) in the respective fibers/natural fibers. Thus, for instance, determining the flame retardant concentrations and/or the carbon to phosphorus ratio (C/P), the carbon to nitrogen ratio (C/N) and/or the phosphorus to nitrogen ratio (P/N) may change, e.g., increase, the total surface energy of the fibers. This may allow the total surface energy of the fibers to be controlled/adjusted according to the application and/or demands of the composite material.

Alternatively, or additionally, the fibers may be treated by etching and/or bleaching the fibers and/or covalently bonding molecules which have heteroatoms to a surface of the fibers which may also increase the total surface energy. Alternatively, or additionally, the fibers may be treated mechanically by one or more mechanical treatments which may roughen the surface and thus increase an overall surface of the fibers. This may also increase the total surface energy of the fibers. The inventors have found that increasing the total surface energy of the fibers, particularly the natural fibers, included in the composite material may improve the adherence properties of the fibers/natural fibers within the matrix, e.g., by increasing the wettability of the fibers/natural fibers, in particular with respect to the matrix.

In particular, the fibers/natural fibers included in the composite material may be matched to one or more matrix materials based at least on the total surface energy of the fibers/natural fibers. Preferably, the fibers and the matrix material(s) included in the composite material have a relatively low difference between the total surface energy of the fibers and the total surface energy of the cured matrix material(s). This may increase, or further increase, the adherence properties of the fibers to the matrix and thus may increase one or more properties, preferably one or more mechanical properties, for instance a tensile ultimate strength, of the composite material.

Preferably, the matrix includes at least one thermoset, preferably a thermosetting resin, preferably a furan resin, preferably including polyfurfuryl alcohol (PFA). PFA resin may be made using sugar cane waste and/or bagasse. Sugar cane waste and bagasse are by-products of sugar production which do not require additional arable land. This may reduce the ecological footprint of the composite material.

Preferably, the natural fibers are impregnated by the flame retardant.

Preferably, the natural fibers are substantially saturated with the flame retardant.

Preferably, the flame retardant arranged in at least a section of the natural fibers accounts for

1.5 wt% to 30.0 wt%, preferably 1.5 wt% to 25.0 wt%, more preferably 1.5 wt% to 20.0 wt%, more preferably 1.5 wt% to 15.0 wt%, more preferably 2 wt% to 10.0 wt%, more preferably

2.5 wt% to 7 wt%, more preferably 3.0 wt% to 8 wt%, more preferably 3.0 wt% to 8.0 wt%, most preferably 4.0 wt% to 7.0 wt%, of a total weight of the natural fibers. The total weight of the natural fibers includes the weight of the flame retardant(s). The total weight of the natural fibers including the weight of the flame retardant may be determined by weighing the natural fibers after the flame retardant has been applied to the natural fibers and has completely dried. The weight is determined in a conditioned environment with equilibrium moisture content at 22°C and 50% relative humidity. The weight of the flame retardant may be determined by weighing the natural fibers before the flame retardant has been applied to the natural fibers, in a conditioned environment with equilibrium moisture content at 22°C and 50% relative humidity, and calculating the difference between the determined total weight of the natural fibers including the weight of the flame retardant and the determined weight of the flame retardant before the flame retardant has been applied to the natural fibers.

Preferably, the natural fibers are at least partially made of plant-based fibers. Preferably, the flame retardant included in the plant-based fibers includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) in the plant-based fibers (including the flame retardant) ranges from 10 to 200, more preferably from 10 to 140, more preferably 20 to 110, more preferably 20 to 90, more preferably 30 to 90, most preferably from 80 to 90. Providing the aboveidentified ranges for a ratio of carbon (C) to phosphorus (P) in the plant-based fibers may achieve relatively high flame retardant properties in the plant-based fibers. Moreover, the above-identified ranges for a ratio of carbon (C) to phosphorus (P) in the plant-based fibers may strike a balance for providing relatively high flame retardant properties in the plant-based fibers, while limiting one or more negative effects the flame retardant may have on the composite material, e.g., a reduced degree of adherence of the fibers in the matrix.

The ratios of the elements, e.g., a ratio of carbon (C) to phosphorus (P), are calculated as the ratios between the w% of the elements as determined by trace element analysis.

Preferably, the natural fibers are at least partially made of plant-based fibers. Preferably, the flame retardant included in the plant-based fibers includes nitrogen (N), wherein a ratio of carbon (C) to nitrogen (N) in the plant-based fibers (including the flame retardant) ranges from 5 to 40, more preferably from 10 to 40, more preferably from 10 to 30, more preferably from 10 to 25, most preferably from 15 to 25.

Preferably, the natural fibers are at least partially made of plant-based fibers. Preferably, the flame retardant included in the plant-based fibers includes a P-N (nitrogen-phosphorus) type flame retardant, wherein a ratio of phosphorus (P) to nitrogen (N) in the plant-based fibers (including the flame retardant) ranges from 0.2 to 0.6, more preferably from 0.2 to 0.5, preferably from 0.2 to 0.45, more preferably from 0.25 to 0.35, most preferably from 0.27 to 0.33.

Preferably, the flame retardant arranged in at least a section of the natural fibers is an N type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a nitrogen content within the natural fibers accounts for at least 0.5 wt%, more preferably 0.5 wt% to 7 wt%, more preferably 0.5 to 6 wt%, more preferably 0.5 to 5 wt%, more preferably 1 wt% to 4.0 wt%, more preferably 1.5 wt% to 4.0 wt%, most preferably 1.5 wt% to 3.5 wt% of a total weight of the natural fibers.

Preferably, the flame retardant arranged in at least a section of the natural fibers is a P type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a phosphorus content within the natural fibers accounts for at least 0.2 wt%, more preferably 0.2 wt% to 3 wt%, more preferably 0.2 wt% to 2.0 wt%, more preferably 0.2 to 1.5 wt%, more preferably 0.4 wt% to 1.3 wt%, more preferably 0.4 wt% to 0.7 wt%, most preferably 0.4 wt% to 0.6 wt% of a total weight of the natural fibers.

Preferably, the flame retardant arranged at least partially within the matrix accounts for 10 wt% to 40 wt%, more preferably 15 wt% to 35 wt%, most preferably 20 wt% to 30 wt% of a total weight of the matrix.

Preferably, the flame retardant arranged at least partially within the matrix is a P type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a phosphorus content in the matrix accounts for at least 1.0 wt%, more preferably from 1 wt% to 5 wt%, more preferably from 1.5 wt% to 4 wt%, more preferably from 1.9 wt% to 3.5 wt%, most preferably from 1.9 wt% to 2.9 wt% of a total weight of the matrix.

A P type flame retardant refers to a flame retardant which includes at least one phosphorus compound and/or at least one nitrogen phosphorus compound.

An N type flame retardant refers to a flame retardant which includes at least one nitrogen compound and/or at least one nitrogen phosphorus compound.

A P-N type flame retardant refers to a flame retardant which includes: at least one nitrogen phosphorus compound, and/or at least one phosphorus compound and at least one nitrogen compound.

The term nitrogen phosphorus compound means that said compound includes phosphorus and nitrogen within one molecule or chemical species - such as organic amino phosphate, aminomethylphosphonate or the like.

Within the context of the present disclosure, determining the contents of chemical elements, such as nitrogen and phosphorus content in the flame retardant described above, and for any other configuration defining contents of chemical elements, Trace Elemental Analysis (TEA) may be employed to determine said content(s) of chemical elements. For instance, TEA may be performed by the Fakultat fur Chemie, Mikroanalytisches Laboratorium, Universitat Wien, Wahringer StraRe 42, 1090 in Vienna, Austria, in particular according to their standards, e.g., for detecting carbon (C), hydrogen (H), nitrogen (N), sulfur (S), oxygen (O) and phosphorus (P). The respective samples were conditioned to equilibrium moisture content at 22°C and 50% relative humidity before measurement.

For analyzing C/H/N/S, an EA 3000 CHNS-O-Elemental Analyzer (Eurovector) may be used. For the analysis of O, a sample may be reductively pyrolized in a glassy carbon tube at 1.480°C in a Hekatech HT 1500 and the O detection may be performed by a chromatography system of EA 3000. P may be quantitatively converted into ortho-phosphate after mineralization by acidic pulping (sulfuric acid / nitric acid). Quantitative determination may be performed by photometry using the Molybdenum blue reaction.

Preferably, the flame retardant arranged at least partially within the matrix is an N type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a nitrogen content within the matrix accounts for at least 1.0%, more preferably 1 wt% to 7 wt%, more preferably 1 wt% to 6 wt%, more preferably 2 wt% to 5 wt%, more preferably 2 wt% to 4 wt%, most preferably 3 wt% to 4 wt% of a total weight of the matrix.

Preferably, the flame retardant arranged at least partially within the matrix is a P type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a ratio of phosphorus content to nitrogen content within the matrix is 0.1 to 3, more preferably 0.1 to 2, more preferably 0.3 to 1.25, more preferably 0.5 to 0.95, more preferably 0.6 to 0.85, more preferably 0.65 to 0.8, most preferably 0.7 to 0.75.

Preferably, the flame retardant arranged at least partially within the matrix includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) within the matrix ranges from 5 to 50, more preferably from 10 to 40, more preferably 15 to 35, more preferably 20 to 30, more preferably 20 to 25, most preferably 21.5 to 23.5.

Preferably, the flame retardant arranged at least partially within the matrix includes nitrogen (N), wherein a ratio of carbon (C) to nitrogen (N) within the matrix ranges from 3 to 8, more preferably 6 to 40, more preferably 12.5 to 20, more preferably 14.5 to 18.5, most preferably 15.5 to 17.5.

Suitable and/or advantageous flame retardants for the matrix may include one or more of the following: aluminium hydroxide, zinc borate, borate, one or more further borate compounds, ammonium monophosphate, ammonium polyphosphate, aluminum hydroxide, ammonium polyphosphate, calcium carbonate, gypsum, calcium sulfate hemihydrate, organic phosphonic acid ester, such as CAS No. 3001-98-7.

Alternatively, or additionally, the flame retardant(s) for the matrix preferably includes at least one phosphorus compound, preferably at least one nitrogen phosphorus compound, most preferably at least one phosphorus compound and at least one nitrogen compound.

The phosphorus compound may include one or more of the following phosphates: phosphate, phosphoric acid organic phosphate, e.g., alkyl phosphate oligomer, such as, CAS No. 184538- 58-7, triethyl ester of phosphoric acid, aromatic phosphate ester, phosphorus polyol, OH- terminated phosphorus polyol, diphenyl phenyl phosphate (DPK), cresyl diphenyl phosphate (CDP), TCPP tris(l-chloro-2-propyl)phosphate (TCPP), triethyl phosphate (TEP), Tris(2- chloroethyl) phosphate (TCEP), Diphenyl tolyl phosphate, and Diphenylcresylphosphate (DPK).

Alternatively, or additionally, the phosphorus compounds may include one or more of the following phosphonates: inorganic phosphonate, organic phosphonic acid ester, and organic phosphonate.

Preferably, the one or more phosphonates are halogen free, e.g., dimethyl propylphosphonate (DMPP), methylphosphonic acid, diethyl ethylphosphonate (DEEP), and dimethyl methylphosphonate (DMMP).

Alternatively, or additionally the flame retardant(s) for the matrix includes at least one nitrogen compound, such as at least one of ammonia and its salts, a primary amine, such as monoethanolamine, a secondary amine, a tertiary amine and its salts, derivates of urea and melamine and its salts, melamine cyanurate, and amidinourea and its salts.

The nitrogen phosphorus compound may include one or more of the following: amino phosphate, amino phosphonate, ammonium polyphosphate, ammonium phosphate, organic amino phosphate, even more preferably organic amino phosphonate (e.g. Diethyl-bis(2- hydroxyethyl), aminomethylphosphonate, salt of amines, urea-derivates with phosphorcontaining acids, and salt of urea derivates with organic phosphonic ester.

Preferably, the flame retardant(s) included in the matrix is/are substantially free of halogenides, more preferably free of organic halogenides. Preferably the flame retardant(s) included in the matrix is/are free of boron, its salts, and compounds.

Suitable and/or advantageous flame retardants for the natural fibers may include one or more of the following: aluminium hydroxide, Zinc borate, borate, other borate compounds, ammonium monophosphate, ammonium polyphosphate, aluminum hydroxide, ammonium polyphosphate, calcium carbonate, gypsum, calcium sulfate hemihydrate, organic phosphonic acid ester, such as CAS No. 3001-98-7.

Alternatively, or additionally, the flame retardant(s) for the natural fibers may include at least one phosphorus compound, preferably at least one phosphorus compound and at least one nitrogen compound, most preferably one nitrogen phosphorus compound.

The phosphorus compound may include one or more of the following phosphates: phosphate, phosphoric acid organic phosphate, e.g., alkyl phosphate oligomer, such as CAS No. 184538- 58-7), triethyl ester of phosphoric acid, aromatic phosphate ester, phosphorus polyol, OH- terminated phosphorus polyol, diphenyl phenyl phosphate (DPK), cresyl diphenyl phosphate (CDP), TCPP tris(l-chloro-2-propyl)phosphate (TCPP), triethyl phosphate (TEP), Tris(2- chloroethyl) phosphate (TCEP), Diphenyl tolyl phosphate, and Diphenylcresylphosphate (DPK).

Alternatively, or additionally, the phosphorus compounds may include one or more of the following phosphonates: inorganic phosphonate, organic phosphonic acid ester, and organic phosphonate. Preferably, the one or more phosphonates are halogen free, e.g., dimethyl propylphosphonate (DMPP), methylphosphonic acid, diethyl ethylphosphonate (DEEP), and dimethyl methylphosphonate (DMMP).

Alternatively, or additionally the flame retardant(s) for the natural fibers may include at least one nitrogen compound, such as at least one of ammonia and its salts, a primary amine, a secondary amine, a tertiary amine and its salts, derivates of urea and melamine and its salts, melamine cyanurate, and amidinourea and its salts.

The nitrogen phosphorus compound may include one or more of the following: amino phosphate, amino phosphonate, ammonium polyphosphate, ammonium phosphate, organic amino phosphate, even more preferably organic amino phosphonate, such as Diethyl-bis(2- hydroxyethyl), aminomethylphosphonate, salt of amines, urea-derivates with phosphorcontaining acids, and salt of urea derivates with organic phosphonic ester

Preferably the flame retardant(s) for the natural fibers are substantially free of halogenides, more preferably free of organic halogenides.

Preferably the flame retardant(s) for the natural fibers are free of boron, its salts, and compounds.

Preferably the flame retardant(s) for the natural fibers include at least one organic phosphorus compound.

Preferably, the composite material includes a total content of flame retardant of at least 4 wt%, preferably from 4 wt% to 40 wt%, more preferably from 5 wt% to 30 wt%, more preferably from 5 wt% to 20 wt%, most preferably from 10 wt% to 20 wt%, of a total weight of the composite material.

Preferably, the flame retardant(s) arranged in the composite material include(s) nitrogen (N), wherein a nitrogen (N) content in the composite material is between 1 wt% to 10 wt%, more preferably 1 wt% to 5 wt%, more preferably 1.5 wt% to 4 wt%, more preferably 1.9 wt% to 3 wt%, more preferably 2.3 wt% to 3.0 wt%, most preferably 2.3 wt% to 2.5 wt% of a total weight of the composite material.

Preferably, the flame retardant(s) arranged in the composite material include(s) nitrogen (N) and phosphorus (P), wherein a ratio of phosphorus (P) to nitrogen (N) in the composite material is from 0.3 to 1, more preferably from 0.3 to 0.8, more preferably from 0.35 to 0.7, more preferably from 0.4 to 0.7, more preferably from 0.45 to 0.65, more preferably from 0.50 to 0.60, most preferably from 0.52 to 0.56.

Preferably, the flame retardant arranged in the composite material includes nitrogen (N), wherein a ratio of carbon (C to nitrogen (N) in the composite material is from 10 to 50, more preferably from 10 to 40, more preferably from 10 to 30, more preferably from 15 to 30, more preferably from 15 to 25, more preferably from 17.3 to 22.8, more preferably from 17.5 to 20.5, more preferably from 18.0 to 19.0, most preferably from 18.2 to 18.8. Preferably the flame retardant arranged in the composite material includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) in the composite material is from 10 to 85, more preferably from 10 to 70, more preferably from 20 to 60, more preferably from 20 to 50, more preferably from 20 to 40, more preferably from 30 to 40, more preferably from 32 to 35.5, most preferably from 33.5 to 35.5.

Preferably, the flame retardant(s) arranged in the composite material include(s) phosphorus (P), wherein a phosphorus (P) content in the composite material is between 0.5 wt% to 10 wt%, more preferably 0.5 wt% to 5 wt%, more preferably 0.9 wt% to 4 wt%, more preferably 1 wt% to 3 wt%, more preferably 1.0 wt% to 3.0 wt%, more preferably 1.0 wt% to 2.5 wt%, most preferably 1.0 wt% to 2.0 wt% of a total weight of the composite material.

Preferably, the flame retardant arranged at least partially within the matrix and/or the flame retardant arranged in at least a section of the natural fibers includes a salt formed from an organic amine compound and/or an organic phosphonic acid compound.

Preferably, the matrix and the natural fibers are free of a bonding agent. A bonding agent is to be understood as one or more additives which may promote adhesion of the natural fibers to or within the matrix and are purposefully used, intended and applied as such. Agents belonging to the class of flame retardants, such as those enumerated in this patent, are not considered to be bonding agents. The inventors have discovered that by configuring the fibers, e.g., the natural fibers, and the matrix accordingly, such as by means of the embodiments described herein, e.g., by pairing flax fibers and/or viscose fibers with one or more certain biobased matrices, in particular furan resin, and/or by providing the fibers, particularly the natural fibers, with at least a certain degree or threshold of the surface energy, a sufficient adherence of the fibers, particularly natural fibers, to or within the matrix may be achieved such that bonding agents may be omitted from the composite material. Since most bonding agents include anhydride or are reaction products of the fiberwith anhydride, which may have adverse health effects, such as by negatively affecting the respiratory tract, in particular when exposed thereto for extended periods of time, enabling such bonding agents to be omitted from the composite material may have health benefits.

Preferably, the natural fibers and/or the matrix, preferably the composite material, is/are substantially free of volatile organic compounds (VOC). "Sustantially free" means that the respective material does not exceed the criteria listed in "Emissionsarme Mbbel und Lattenroste aus Holz und Holzwerkstoffen", DE-UZ 38, Issue January 2022, Version 1, Chapter 3.2 (link: https://produktinfo.blauer-engel.de/uploads/criteriafile/de/DE-UZ%2038-202201- de-Kriterien-Vl.pdf).

Preferably, the composite material has a tensile ultimate strength of at least 300 MPa, more preferably at least 400 MPa, more preferably at least 450 MPa, more preferably at least 500 MPa, more preferably at least 600 MPa, more preferably at least 700 MPa, more preferably at least 800 MPa, more preferably at least 900 MPa, more preferably at least 1000 MPa, more preferably at least 1100 MPa, more preferably at least 1200 MPa, more preferably at least 1300 MPa, more preferably at least 1400 MPa, most preferably at least 1500 MPa. The tensile ultimate strength is determined in a direction which has the greater tensile strength, which is generally in a direction, i.e., along, the fibers. The tensile ultimate strength may be determined based on 8 layers of the composite material, configured as prepregs, in an autoclave under vacuum. A curing time, a temperature and a pressure may be optimized to reach optimal strengths. The autoclave pressure may be set to 4 bar and a vacuum pressure of the vacuum bag may be -1 bar and the temperature may be 100°C. Prior to testing, the test samples may be conditioned in accordance with ASTM D 618-2008 and ASTM D 5229/D5229M. The test samples may be conditioned in distilled water for at 23 +/-1° Celsius until equilibrium in accordance with ASTM D 618-2008 section 9.3 Procedure D (24/23/water). The samples and the test may be in accordance with DIN EN 2747 (1998) for glass fiber reinforced plastics.

Preferably, at least 10 wt%, preferably at least 15 wt%, preferably at least 20 wt%, more preferably at least 25 wt%, more preferably at least 30 wt%, more preferably at least 35 wt%, more preferably at least 40 wt%, more preferably at least 45 wt%, more preferably at least 50 wt%, more preferably at least 55 wt%, more preferably at least 60 wt%, more preferably at least 65 wt%, more preferably at least 70 wt%, more preferably at least 75 wt%, most preferably at least 80 wt%, of the natural fibers is made of natural organic material.

Preferably, the matrix is at least partially made of organic material, preferably wherein at least 10 wt%, more preferably at least 15 wt%, more preferably at least 20 wt%, more preferably at least 25 wt%, more preferably at least 30 wt%, more preferably at least 35 wt%, more preferably at least 40 wt%, more preferably at least 45 wt%, more preferably at least 50 wt%, more preferably at least 55 wt%, more preferably at least 60 wt%, more preferably at least 65 wt%, more preferably at least 70 wt%, more preferably at least 75 wt%, most preferably at least 80 wt%, of the matrix is made of organic material. The organic material included in the matrix may be natural and/or non-natural, e.g., synthetic. More preferably the carbon (C) included in the matrix stems at least partially from one or more raw plant materials that were processed to form the matrix. Preferably at least 40%, more preferably at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90%, most preferably at least 95% of the carbon included in the matrix stems from one or more raw plant materials which were processed to form the matrix.

Preferably, the composite material is configured to be used in a paneling element for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft.

Preferably, the composite material is configured for use in fire hazardous environments, preferably in a powered vehicle, preferably a powered aircraft and/or a powered watercraft.

Preferably, the composite material is configured to pass the vertical burn test.

The vertical burn test may be performed as defined by the U.S. Federal Aviation Administration (FAA) in the Code of Federal Regulations (CFR), more specifically in CFR Title 14, Chapter 1, Subchapter C, Appendix F to Part 25, Part I (a )(l)(i) in connection with CFR Title 14, Chapter 1, Subchapter C, Appendix F to Part 25, Part I (b)(4), also known as the 60 second vertical burn test. Additionally, or alternatively, the vertical burn test may be performed pursuant to CFR Title 14, Chapter 1, Subchapter C, Appendix F to Part 25, Part I (a)(1)(H) in connection with CFR Title 14, Chapter 1, Subchapter C, Appendix F to Part 25, Part I (b)(4), also known as the 12 second vertical burn test. The version of the above-identified Code of Federal Regulations (CFR) which is in force on May 20, 2022 is to be applied.

Additionally, or alternatively, the composite material may be configured to pass the Heat Release Rate (OSU) test. The OSU determines a heat release rate of materials when exposed to radiant heat. The OSU may be performed in accordance with ASTM E906-09. The test is commonly used to show compliance with CFR Title 14, Chapter 1, Subchapter C, Part 25, Subpart D, Fire Protection, § 25.853(d) which is in force on May 20, 2022. Also, Title 14 Chapter I Subchapter C Part 25 Appendix F to Part 25 is to be taken into consideration for performing the Heat Release Rate (OSU) test.

Additionally, or alternatively, the composite material may be configured to pass toxicity test according to Boeing BSS 7239 which is in effect on May 20, 2022. Additionally, or alternatively, the composite material may be configured to pass the smoke density test which may be performed in accordance with the American Society of Testing and Materials (ASTM) Standard Test Method ASTM F814-83. The test is commonly used to show compliance with CFR Title 14, Chapter 1, Subchapter C, Part 25, Appendix F to Part 25, Part V (b).

Preferably, the composite material is configured to pass the low spread of flame test according to IMO 2010 FTP Code Part 5 (referred to in the Maritime Equipment Directive 2014/90/EU of July 23^rd 2014 class 3.18a).

Preferably, the composite material is configured to pass the smoke and toxicity tests according to IMO 2010 FTPC Part 3 (referred to in the Maritime Equipment Directive 2014/90/EU of July 23^rd 2014 class 3.18a).

Preferably, the matrix includes at least one first flame retardant arranged within the matrix and the natural fibers include at least one second flame retardant arranged in at least a section of the natural fibers, wherein the first flame retardant and the second flame retardant are different. The matrix and the natural fibers are preferably treated separately, i.e., in separate treatment processes, by their respective flame retardant(s). Preferably, the first flame retardant and the second flame retardant have different compositions, e.g., they may differ in at least one component of the flame retardants and/or a content or concentration of at least one component of the flame retardants.

Preferably, the first flame retardant and the second flame retardant differ in one or more of the following properties: a solubility, a nitrogen (N) content, a phosphorus (P) content, a boron (B) content, an aluminum (Al) content, a nitrogen to phosphorus ratio and a concentration of the respective flame retardant within the matrix and the natural fibers, respectively. The nitrogen content, phosphorus content, boron content and aluminum content are determined by Trace Elemental Analysis (TEA).

Preferably, the first flame retardant is substantially soluble in the matrix in an A-stage of the matrix and the second flame retardant is substantially soluble in water. As discussed at the beginning, the composite material, in particular when configured as a prepreg, may include three curing stages, which are referred to A-stage, B-stage, and C-stage, respectively.

Preferably, the first flame retardant contains particulates or powder which can form a suspension in the matrix in an A-stage of the matrix and the second flame retardant is substantially soluble in water.

Preferably, the natural fibers have an intrinsic density of at most 2 g/cm3, preferably at most 1.9 g/cm3, more preferably at most 1.8 g/cm3, more preferably at most 1.7 g/cm3, more preferably at most 1.6 g/cm3, more preferably at most 1.5 g/cm3, more preferably at most 1.4 g/cm3, more preferably at most 1.3 g/cm3, more preferably at most 1.2 g/cm3, more preferably at most 1.1 g/cm3, more preferably at most 1 g/cm3, more preferably at most 0.9 g/cm3, more preferably at most 0.8 g/cm3, more preferably at most 0.7 g/cm3, more preferably at most 0.6 g/cm3, more preferably at most 0.5 g/cm3, most preferably at most 0.4 g/cm3.

The term "intrinsic density" refers to a natural density of the fibers, i.e., a natural density which has not been altered via one or more chemical and/or physical treatments and/or modifications. Thus, for instance, the intrinsic density is determined before the flame retardant has been added thereto. The intrinsic density of the natural fibers may be determined by determining, e.g., measuring, a mass of one or more natural fibers, preferably a single natural fiber, as is known in the art, and by determining, e.g., measuring, a volume of the one or more natural fibers, preferably the single natural fiber, as is known in the art. The density may be determined by dividing the mass of the one or more natural fibers, preferably the single fiber, by the volume of the one or more natural fibers, preferably the single fiber. Values determined at 22°C and 50% relative humidity.

A lower density may allow more flame retardant to be absorbed by the fibers.

Preferably, the natural fibers have an intrinsic porosity of at least 6%, preferably at least 8%, more preferably at least 10%, more preferably at least 12%, more preferably at least 14%, more preferably at least 16%, more preferably at least 18%, more preferably at least 20%, more preferably at least 22%, more preferably at least 24%, more preferably at least 26%, more preferably at least 28%, most preferably at least 30%.

The intrinsic porosity may be determined according to "The determination of porosity and cellulose content of plant fibers by density methods" by L. Y. Mwaikambo and M. P. Ansell, December 2001, Journal of Materials Science Letters 20(23):2095-2096, which is herewith incorporated by reference in its entirety. A higher intrinsic porosity may allow more flame retardant to be absorbed by the natural fibers. Moreover, this may allow a relatively large amount of flame retardant to be absorbed within the natural fibers, in particularly within the voids of the natural fibers, while minimizing negative effects the flame retardant may have on an adherence of the natural fibers to the matrix.

Preferably, the matrix and the at least one flame retardant arranged at least partially within the matrix account for 30 wt% to 60 wt%, preferably 35 wt% to 55 wt%, more preferably 40 wt% to 50 wt% of the total weight of the composite material, preferably configured as a prepreg.

Preferably, the total surface energy of the natural fibers is at least 20 mN/m, more preferably at least 25 mN/m, more preferably at least 30 mN/m, most preferably at least 35 mN/m. The above-identified values for the total surface energy are determined for a state of the total surface energy which includes any treatments which may be applied to the natural fibers, e.g., one or more treatments for increasing the total surface energy of the natural fibers.

The total surface energy of the fibers and/or of the matrix may be determined by determining one or more contact angles of at least one liquid, e.g., at least one testing liquid on a surface of the fibers.

For determining the total surface energy of the fibers, 60 mg of fibers are pressed together to form a pressed body with a substantially closed and substantially even outer surface. To obtain this result e.g., for flax fibers a press force of 10 tons for a duration of 2 minutes with a Specac manual hydraulic press may be used. The contact angle determinations are performed with three test liquids (water, ethylene glycaol, diiodmethan) which feature known polar and disperse proportions of surface energy.

For determining the total surface energy of the matrix, an even film of the substantially cured matrix is prepared. Such a film may be prepared by drying an A-stage liquid film of the matrix, e.g., resin, at moderate temperature and sufficient ventilation to remove the solvents. The film may be pressed between hot press plates to get an even surface and to cure the film.

The contact angles are determined with a DataPhysics OCA 35 applying the Sessile Dropmethod (static contact angle) with a drop volume of 1.5 pl, a drop rate of 1 pl/s, an ellipse fitting evaluation and a manual base line determinaton. Surface tension(s) of the liquids are taken from Table 1. The contact angle is measured directly after stabilization of a drop of the liquid on the respective surface, determined from the measurements a the base line diameter of the drop and the drop volume, before swelling of the surface and onset of evaporation phenomena. The contact angle is calculated as the mean average of the right angle and the left angle of the drop of liquid. 10 single values of the contact angle were averaged for each sample and for each test liquid.

Based on the determined contact angles of the three test liquids with known total surface tension (in mN/m resp. mJ/m²) and known proportion of polar and disperse surface tension (in mN/m resp. mJ/m²), as provide in Table 1 below, the total surface energy as well as the polar and disperse components of the surface energy of the samples can be calculated according to the method by Owens, Wendt, Rabel und Kaelble (OWRK), as described in "Estimation of the Surface Free Energy of Polymers" by D. Owens; R. Wendt, In: Journal of Applied Polymer Science , Band 13, 1969, pages 1741-1747, which is herewith incorporated by reference. It is also referred to "Dispersion-Polar Surface Tension Properties of Organic Solids" by D. H. Kaelble, In: The Journal of Adhesion 2(2), 1970, pages 66-81, and "Einige Aspekte der Benetzungstheorie und ihre Anwendung auf die Untersuchung und Veranderung der Oberflacheneigenschaften von Polymeren" by W. Rabel,. In: Farbe und Lack 77,10 1971, pages 997-1005, which are both herewith incorporated by reference.

The surface tension values of the respective test liquids provided in Table 1 were determined at a test liquid temperature of 20°C.

Table 1

Preferably, the total surface energy of the substantially cured matrix, preferably in the B-stage and/or in a substantially completely cured state of the matrix, is less than 70.0 mN/m, more preferably less than 65.0 mN/m, more preferably less than 60 mN/m, most preferably less than 55 mN/m.

Preferably, the total surface energy of at least some of the fibers, preferably at least the natural fibers, more preferably all of the fibers, included in the composite material, have a total surface energy which deviates from the total surface energy of the substantially cured matrix material(s) by less than 40 mN/m, more preferably less than 30.0 mN/m, more preferably less than 25 mN/m, more preferably less than 20 mN/m, more preferably less than 18 mN/m, more preferably less than 16 mN/m, most preferably less than 15 mN/m.

Preferably, the flame retardant is substantially free of halides and/or boron (B). Halides may include chlorine (Cl), bromine (Br), fluorine (F) and Iodine (I). Preferably, the composite material is substantially free of halides and/or boron (B). "Substantially free" means that a content of the respective elements does not exceed 0.5 wt%, more preferably 0.2 wt%, of a total weight of the flame retardant or of the composite material, respectively, as determined by elemental trace analysis.

Preferably, an alkali content in any flame retardant included in the composite material does not exceed 2 wt%, more preferably 1 wt%, more preferably 0.8 wt%, more preferably 0.5 wt%, most preferably 0.2 wt% of a total weight of the flame retardant(s). Preferably, an alkali content in the composite material does not exceed 1 wt%, preferably 0.8 wt%, more preferably 0.5 wt%, most preferably 0.2 wt% of a total weight of the composite material. Alkalis may include alkali metals, e.g., lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr), and alkaline earth metals, e.g., beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra).

The inventors have found that, surprisingly, alkali may limit the strength of composite materials. This may be due to higher material hygroscopy, in particular for the alkali, and/or a local enrichment of alkali at certain positions in the composite materials weaken the cohesion of the composite materials. Thus, omitting alkali, or at least limiting the content of alkali in the composite material, or at least from the flame retardant, may provide the composite with a greater strength compared with composite material which include alkali, in particular higher levels thereof.

Preferably, the natural fibers include flax fibers and/or viscose fibers, and wherein the matrix is at least partially made of furan resin.

The object set out at the beginning is also solved by a component defined by the features of claim 67. The component may be a paneling element, preferably a moulded part, for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft. The component may be at least partially made of a fiber-reinforced composite material according to any of the embodiments described herein.

The features, configurations and/or advantages described above in relation to the fiber- reinforced composite material described herein also apply to the component accordingly.

The object set out at the beginning is also solved by a vehicle defined by the features of claim 68. The vehicle may be a powered vehicle, preferably a powered aircraft and/or a powered watercraft. The vehicle may include a component, preferably a component according to any of the embodiments described herein, preferably a paneling element, preferably a moulded part. The component may be arranged in an interior of the vehicle.

The features, configurations and/or advantages described above in relation to the fiber- reinforced composite material and/or the component described herein also apply to the vehicle accordingly.

The object set out at the beginning is also solved by a method for manufacturing a fiber- reinforced composite material, preferably a fiber-reinforced composite material according to any of the embodiments described herein, as defined by the features of claim 69.

The features, configurations and/or advantages described above in relation to the fiber- reinforced composite material and/or the component and/or the vehicle described herein also apply to the method accordingly.

The method includes the following steps:

(a) providing at least one matrix made of a biobased material;

(b) providing a plurality of natural fibers;

(c) applying at least one flame retardant to the matrix such that the flame retardant is arranged at least partially within the matrix;

(d) applying at least one flame retardant to at least a section of the natural fibers; and

(e) embedding the natural fibers at least partially in the matrix.

The method does not have to be performed in the order of the steps as they are listed above. Thus, the steps of the method may be performed in any sequence.

Preferably, the matrix includes at least one thermoset, preferably a thermosetting resin, preferably substantially based on polyfurfuryl alcohol (PFA) and preferably wherein, after step (e), the matrix is cured, preferably to at least partially (e.g. a B-stage of the matrix), more preferably substantially completely.

Optionally, a plurality of non-natural fibers may also be provided in the composite material, e.g., during step (b), before step (b) and/or after step (b), as explained with respect to the composite material above.

Preferably, steps (c) and (d) are performed before step (e).

Preferably, the natural fibers include organic fibers and/or inorganic fibers.

Preferably, the natural fibers include plant-based fibers.

Preferably, the natural fibers only include plant-based fibers.

Preferably, the natural fibers include flax fibers, preferably only flax fibers.

Preferably, the natural fibers include viscose fibers, preferably only viscose fibers.

Preferably, in step (d), the natural fibers are impregnated by the flame retardant.

Preferably, in step (d), the natural fibers are substantially saturated with the flame retardant.

Preferably, in step (c), at least one first flame retardant is applied to the matrix such that the flame retardant is arranged at least partially within the matrix and, in step (d), at least one second flame retardant is applied to at least a section of the natural fibers, wherein the first flame retardant and the second flame retardant are different.

Preferably, the first flame retardant and the second flame retardant differ in one or more of the following properties: a solubility, a nitrogen (N) content, a phosphorus (P) content, a boron (B) content, an aluminum (Al) content, a nitrogen to phosphorus ratio, and a concentration of the respective flame retardant within the matrix and the natural fibers, respectively.

Examples Example 1 - in accordance with the teaching of the present disclosure

A solution was prepared from 15 wt% Guanyl-urea phosphate (C2H9N4O5P, 98% purity, GUP) in distilled water. The pH-value of the solution was set to 5.5 with ammonia (25% solution). Then the final flame retardant impregnation solution was obtained by mixing this solution with a ratio 1:2 with distilled water. Woven flax fabric with a grammage of about 200g/m² (ampliTex™ 200, twill 2/2, BComp Switzerland) was impregnated in the final flame retardant solution at room temperature for 2 hours. After removing the flax fabric from the impregnation solution, the flax fabric was hung up to drip off for 2 hours. Subsequently the flax fabric was dried with a belt dryer for veneers equipped with heated rollers and a pair of fine mesh steel belts. The temperature of the rollers was set to 100°C and the speed to 4m/min. As a result, the flax fabric with flame retardant was obtained.

Polyfurfuryl alcohol impregnation resin BioRez 080101 was obtained from TransFurans Chemicals bvba (Geel, BE). For enhancing the textile impregnation, the viscosity of PFA was reduced by adding 32 wt. % ethanol, the following substances were added to the respective final concentrations in the final impregnation resin as flame retardants: 3.8 wt% urea, 4.8 wt% monoethanolamine and 8.8 wt% phosphoric acid (supplied as 75 wt% in water). The flax fabric with flame retardant was dip-coated in the final impregnation resin and excess resin was removed by running the flax fabric between rollers.

Ethanol and partly also water were evaporated by storing the pre-impregnated textiles at a temperature of 20°C for 48h. The obtained prepregs had a fiber weight content of 50 wt.%. To obtain samples for flammability tests (OSU, Low Spread of Flame, 60 Seconds (s) Vertical Burn Test) 3 layers of prepreg were assembled in a stack and put into a vacuum bag to harden in the autoclave: the temperature of the process started at room temperature and was then increased to 80°C within 25 minutes. This temperature was held for approximately 20 minutes. Within another 20 minutes the temperature was increased to 100°C and held for 140 minutes. The next 40 minutes the temperature was decreased to around 40°C. The pressure inside of the autoclave was 4 bar and within the vacuum bag was -1 bar during the entire process.

To obtain samples for performing tensile ultimate strength tests, 8 layers of prepreg were assembled in a stack and put into a vacuum bag to harden in the autoclave using the same process. For obtaining the substantially cured film of the final impregnation resin for total surface energy determination 200g/m² final impregnation resin were coated onto an aluminum carrier. The film was dried at a temperature of 20°C for 48h. To obtain a substantially even surface and to cure the resin the carrier was put into a hot press (120°C) for 45 minutes at 70 bar.

The OSU-Test was carried out in accordance with ASTM E906-09. The Low Spread of Flame test was carried out according to IMO 2010 FTPC Part 5.

Priorto testing the tensile ultimate strength, the test samples were conditioned in accordance with ASTM D 618-2008 and ASTM D 5229/D5229M. The test samples were conditioned in distilled water for at 23 +/-1° Celsius until equilibrium in accordance with ASTM D 618-2008 section 9.3 Procedure D (24/23/water). Tests were performed in accordance with DIN EN 2747 (1998) for glass fiber reinforced plastics with the parameters F - Minimum total length: 300 mm, T - Minimum length of the tabs: 75 mm, E - Distance between Grips: 170 mm +/- 1 mm, c - Distance between tabs: 150 mm +/- 0.5, b - Width: 25 mm+/- 0.5 mm, 10 - Gauge length: vertical distance between extensometer arms (50 mm)

The following test results were achieved by the resulting composite material:

Tensile ultimate strength: 823 MPa

OSU: fail

60s Vertical Burn Test: pass (average burn length = 112mm)

Flax with flame retardant: total surface energy = 37.23 mN/m

B-stage film of final impregnation resin: total surface energy = 45.27 mN/m Deviation of total surface energy of the fibers and the matrix = 8.04 mN/m

Example 2 - NOT in accordance with the teaching of the present disclosure as the fibers are not impregnated with flame retardant

The same process as in Example 1 was performed, except that the fibers were not impregnated with flame retardant.

The following test results were achieved by the resulting composite material:

Tensile ultimate strength: 762 MPa

OSU: fail

Low Spread of Flame: fail

60s Vertical Burn Test: fail (average burn length > 250 mm) Example 3 - NOT in accordance with the teaching of the present disclosure as the fibers are not impregnated with flame retardant

The same process as in Example 2 was performed, except that the final concentrations of the flame retardants in the final impregnation resin were increased to 150% of their respective concentrations in example 2.

The following test results were achieved by the resulting composite material:

Tensile ultimate strength: 435 MPa

OSU: fail

Low Spread of Flame: fail

60s Vertical Burn Test: fail (average burn length = 207 mm)

Example 4 - in accordance with the teaching of the present disclosure, containing more than the minimal share of inorganic fibers to pass OSU-test

The same process as in Example 1 was performed, except that a 170 g/m² carbon / flax hybrid fabric with a carbon content of 49% (ampliTex™ 5027-4 UD tape fabric, BComp Switzerland) was used instead of the flax fabric.

The following test results were achieved by the resulting composite material:

Tensile ultimate strength: 982 MPa

OSU: pass

Low Spread of Flame: pass

60s Vertical Burn Test: pass (average burn length = 68 mm)

Smoke- und Toxicity-Tests: pass

Carbon / flax hybrid fabric with flame retardant: total surface energy = 38.14 mN/m

B-stage film of final impregnation resin: total surface energy = 45.27 mN/m

Deviation of the total surface energy of the fibers and the matrix = 7.13 mN/m

Alternatively for all examples FURACURE R 416 from Bitrez Ltd (Nr Wigan, UK) may be used as an impregnation resin when diluted with Ethanol to 53% solid content before adding the flame retardant. Prepreg processing can be performed analogously to above and overall performance results are comparable to the procedure with PFA BioRez 080101.

The following list of aspects provides alternative and/or further features of the invention: A composite material, including: at least one matrix made of a biobased material; and a plurality of natural fibers which are at least partially embedded within the matrix; wherein the matrix includes at least one flame retardant, preferably arranged at least partially within the matrix, and/or wherein the natural fibers include at least one flame retardant, preferably arranged in at least a section of the natural fibers. The composite material according to aspect 1, wherein the composite material includes a plurality of organic fibers and/or a plurality of inorganic fibers, preferably wherein the composite material includes one or more of the following: a plurality of natural organic fibers, a plurality of natural inorganic fibers, a plurality of synthetic organic fibers and a plurality of synthetic inorganic fibers. The composite material according to aspect 1 or 2, wherein the natural fibers include plant-based fibers, preferably only plant-based fibers. The composite material according to any of the preceding aspects, wherein the flame retardant arranged in at least a section of the natural fibers has been applied to at least a portion of the natural fibers before the natural fibers have been embedded at least partially in the matrix. The composite material according to any of the preceding aspects, wherein the natural fibers include one or more of the following: viscose fibers, flax fibers, hemp fibers, bagasse fibers, bamboo fibers, kenaf fibers, jute fibers, ramie fibers, abaca fibers, sisal fibers, coir fibers, oil palm fibers, pineapple fibers and curaua fibers. The composite material according to any of the preceding aspects, wherein the natural fibers include flax fibers, preferably only flax fibers. The composite material according to any of the preceding aspects, wherein the natural fibers include viscose fibers, preferably only viscose fibers. The composite material according to any of the preceding aspects, wherein the fibers included in the composite material only include viscose fibers and flax fibers. The composite material according to any of the preceding aspects, wherein the matrix includes at least one thermoset, preferably a thermosetting resin, preferably including polyfurfuryl alcohol (PFA). The composite material according to any of the preceding aspects, wherein at least the natural fibers are impregnated by the flame retardant. The composite material according to any of the preceding aspects, wherein the flame retardant arranged in at least a section of the natural fibers accounts for 1.5 wt% to 30 wt%, preferably 1.5 wt% to 25 wt%, more preferably 1.5 wt% to 20 wt%, more preferably 1.5 wt% to 15 wt%, more preferably 2 wt% to 10 wt%, more preferably 2.5 wt% to 7 wt%, more preferably 3.0 wt% to 8.0 wt%, more preferably 3.0 wt% to 7.0 wt%, more preferably 4.0 wt% to 7.0 wt%, of a total weight of the natural fibers. The composite material according to any of the preceding aspects, wherein the natural fibers are at least partially made of plant-based fibers, wherein the flame retardant included in the plant-based fibers includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) in the plant-based fibers, including the flame retardant, ranges from lOto 200, more preferably from lOto 140, more preferably from 20 to 110, more preferably 20 to 90, more preferably 30 to 90, most preferably from 80 to 90. The composite material according to any of the preceding aspects, wherein the natural fibers are at least partially made of plant-based fibers, wherein the flame retardant included in the plant-based fibers includes nitrogen (N), wherein a ratio of carbon (C) to nitrogen (N) in the plant-based fibers, including the flame retardant, ranges from 5 to 40, preferably from 10 to 40, more preferably from 10 to 30, more preferably from 10 to 25, most preferably from 15 to 25. The composite material according to any of the preceding aspects, wherein the natural fibers are at least partially made of plant-based fibers, wherein the flame retardant included in the plant-based fibers includes a P-N (nitrogen-phosphorus) type flame retardant, wherein a ratio of phosphorus (P) to nitrogen (N) in the plant-based fibers (including the flame retardant) ranges from 0.2 to 0.6, more preferably from 0.2 to 0.5, preferably from 0.2 to 0.45, more preferably from 0.25 to 0.35, most preferably from 0.27 to 0.33. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix accounts for 10 wt% to 40 wt%, more preferably 15 wt% to 35 wt%, most preferably 20 wt% to 30 wt% of a total weight of the matrix. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix is a P type, or preferably P-N (nitrogen-phosphorus) type, flame retardant, wherein a phosphorus content in the matrix accounts for at least 1 wt%, more preferably from 1 wt% to 5 wt%, more preferably from 1.5 wt% to 4 wt%, more preferably from 1.9 wt% to 3.5 wt%, most preferably 1.9 wt% to 2.9 wt% of a total weight of the matrix. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix is an N type flame retardant, preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a nitrogen content in the matrix accounts for at least 1 wt%, more preferably from 1 wt% to 7 wt%, more preferably from 1 wt% to 6 wt%, more preferably from 2 wt% to 5 wt%, more preferably from 2 wt% to 4 wt%, most preferably from 3 wt% to 4 wt% of a total weight of the matrix. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix is a P type flame retardant, preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a ratio of a phosphorus content to a nitrogen content in the matrix is 0.1 to 3, preferably 0.1 to 2, more preferably 0.3 to 1.25, more preferably 0.5 to 0.95, more preferably 0.6 to 0.85, more preferably 0.65 to 0.8, most preferably 0.7 to 0.75. The composite material according to any of the preceding aspects, wherein the flame retardant arranged in at least a section of the natural fibers is an N type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a nitrogen content within the natural fibers accounts for at least 0.5 wt%, preferably 0.5 wt% to 7 wt%, more preferably 0.5 to 6 wt%, more preferably 0.5 to 5 wt%, more preferably 1 wt% to 4.0 wt%, more preferably 1.5 wt% to 4.0 wt%, most preferably 1.5 wt% to 3.5 wt% of a total weight of the natural fibers. The composite material according to any of the preceding aspects, wherein the flame retardant arranged in at least a section of the natural fibers is a P type flame retardant, more preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a phosphorus content within the natural fibers accounts for at least 0.2 wt%, preferably 0.2 wt% to 3 wt%, more preferably 0.2 wt% to 2.0 wt%, more preferably 0.2 to 1.5 wt%, more preferably 0.4 wt% to 1.3 wt%, more preferably 0.4 wt% to 0.7 wt%, most preferably 0.4 wt% to 0.6 wt% of a total weight of the natural fibers. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) within the matrix ranges from 5 to 50, preferably 10 to 40, more preferably 15 to 35, more preferably 20 to 30, more preferably 20 to 25, most preferably 21.5 to 23.5. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix includes nitrogen (N), wherein a ratio of carbon (C) to nitrogen (N) within the matrix ranges from 3 to 8, preferably 6 to 40, more preferably 12.5 to 20, more preferably 14.5 to 18.5, most preferably 15.5 to 17.5. The composite material according to any of the preceding aspects, wherein the composite material includes a total content of flame retardant of at least 4 wt%, preferably from 4 wt% to 40 wt%, more preferably from 5 wt% to 30 wt%, more preferably from 5 wt% to 20 wt%, most preferably from 10 wt% to 20 wt%, of a total weight of the composite material. The composite material according to any of the preceding aspects, wherein the flame retardant(s) arranged in the composite material include(s) nitrogen (N), wherein a nitrogen (N) content in the composite material is between 1 wt% to 10 wt%, preferably 1 wt% to 5 wt%, more preferably 1.5 wt% to 4 wt%, more preferably 1.9 wt% to 3 wt%, more preferably 2.3 wt% to 3.0 wt%, most preferably 2.3 wt% to 2.5 wt% of a total weight of the composite material. The composite material according to any of the preceding aspects, wherein the flame retardant(s) arranged in the composite material include(s) nitrogen (N) and phosphorus (P), wherein a ratio of phosphorus (P) to nitrogen (N) in the composite material is from 0.3 to 1, preferably 0.3 to 0.8, more preferably from 0.35 to 0.7, more preferably from 0.4 to 0.7, more preferable from 0.45 to 0.65, more preferably from 0.50 to 0.60, most preferably from 0.52 to 0.56. The composite material according to any of the preceding aspects, wherein the flame retardant arranged in the composite material include(s) nitrogen (N), wherein a ratio of carbon (C) to nitrogen in the composite material is from 10 to 50, preferably from 10 to 40, more preferably from 10 to 30, more preferably from 15 to 30, more preferably from 15 to 25, more preferably from 17.3 to 22.8, more preferably from 17.5 to 20.5, more preferably from 18.04 to 19.0, most preferably from 18.2 to 18.8. The composite material according to any of the preceding aspects, wherein the flame retardant arranged in the composite material include(s) phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) in the composite material is from 10 to 85, preferably from 10 to 70, more preferably from 20 to 60, more preferably from 20 to 50, more preferably from 20 to 40, more preferably from 30 to 40, more preferably from 32 to 35.5, most preferably from 33.5 to 35.5. The composite material according to any of the preceding aspects, wherein the flame retardant(s) arranged in the composite material include(s) phosphorus (P), wherein a phosphorus (P) content in the composite material is between 0.5 wt% to 10 wt%, more preferably 0.5 wt% to 5 wt%, more preferably 0.9 wt% to 4 wt%, more preferably 1 wt% to 3 wt%, more preferably 1.0 wt% to 3.0 wt%, more preferably 1.0 wt% to 2.5 wt%, most preferably 1.0 wt% to 2.0 wt% of a total weight of the composite material. The composite material according to any of the preceding aspects, wherein the flame retardant arranged at least partially within the matrix and/or the flame retardant arranged in at least a section of the natural fibers include(s) one or more of the following: a salt formed from an organic amine compound and an organic phosphonic acid compound. The composite material according to any of the preceding aspects, wherein the composite material is free of a bonding agent for promoting bonding between the matrix and the natural fibers. The composite material according to any of the preceding aspects, wherein the natural fibers and/or the matrix, preferably the composite material, is/are substantially free of volatile organic compounds (VOC). The composite material according to any of the preceding aspects, wherein the composite material has a tensile ultimate strength of at least 300 MPa, more preferably at least 400 MPa, more preferably at least 450 MPa, more preferably at least 500 MPa, more preferably at least 600 MPa, more preferably at least 700 MPa, more preferably at least 800 MPa, more preferably at least 900 MPa, more preferably at least 1000 MPa, more preferably at least 1100 MPa, more preferably at least 1200 MPa, more preferably at least 1300 MPa, more preferably at least 1400 MPa, most preferably at least 1500 MPa. The composite material according to any of the preceding aspects, wherein at least 10 wt%, preferably at least 15 wt%, preferably at least 20 wt%, more preferably at least 25 wt%, more preferably at least 30 wt%, more preferably at least 35 wt%, more preferably at least 40 wt%, more preferably at least 45 wt%, more preferably at least 50 wt%, more preferably at least 55 wt%, more preferably at least 60 wt%, more preferably at least 65 wt%, more preferably at least 70 wt%, more preferably at least 75 wt%, most preferably at least 80 wt%, of the natural fibers is made of natural organic material. The composite material according to any of the preceding aspects, wherein the matrix is at least partially made of organic material, preferably wherein at least 10 wt%, more preferably at least 15 wt%, more preferably at least 20 wt%, more preferably at least 25 wt%, more preferably at least 30 wt%, more preferably at least 35 wt%, more preferably at least 40 wt%, more preferably at least 45 wt%, more preferably at least 50 wt%, more preferably at least 55 wt%, more preferably at least 60 wt%, more preferably at least 65 wt%, more preferably at least 70 wt%, more preferably at least 75 wt%, most preferably at least 80 wt%, of the matrix is made of organic material. The composite material according to aspect 34, wherein the carbon (C) included in the matrix stems at least partially from one or more raw plant materials which were processed to form the matrix, preferably wherein at least 40%, more preferably at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90%, most preferably at least 95% of the carbon (C) included in the matrix stems from one or more raw plant materials which were processed to form the matrix. The composite material according to any of the preceding aspects, wherein the composite material is configured to be used in a paneling element for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft. The composite material according to any of the preceding aspects, wherein the composite material is configured for use in fire hazardous environments, preferably in a powered vehicle, preferably a powered aircraft and/or a powered watercraft. The composite material according to any of the preceding aspects, wherein the composite material is configured to pass the vertical burn test. The composite material according to any of the preceding aspects, wherein the composite material is configured to pass the fire testing according to the International Maritime Organization (IMO) 2010 FTP Code Part 5. The composite material according to any of the preceding aspects, wherein the matrix includes at least one first flame retardant arranged at least partially within the matrix and the natural fibers include at least one second flame retardant arranged in at least a section of the natural fibers, wherein the first flame retardant and the second flame retardant are different. The composite material according to any of the preceding aspects, wherein the first flame retardant and the second flame retardant differ in one or more of the following properties: a solubility, a nitrogen content, a phosphorus content, a boron content, an aluminum content, a nitrogen to phosphorus ratio and a concentration of the respective flame retardant within the matrix and the natural fibers, respectively. The composite material according to aspect 40 or 41, wherein the first flame retardant is substantially soluble in the matrix, in an A-stage of the matrix, and the second flame retardant is substantially soluble in water. The composite material according to any of aspects 40 to 42, wherein the first flame retardant includes particulates and/or powder which can form a suspension in the matrix, in an A-stage of the matrix, and the second flame retardant is substantially soluble in water. The composite material according to any of the preceding aspects, wherein the natural fibers have an intrinsic density of at most 2 g/cm3, preferably at most 1.9 g/cm3, more preferably at most 1.8 g/cm3, more preferably at most 1.7 g/cm3, more preferably at most 1.6 g/cm3, more preferably at most 1.5 g/cm3, more preferably at most 1.4 g/cm3, more preferably at most 1.3 g/cm3, more preferably at most 1.2 g/cm3, more preferably at most 1.1 g/cm3, more preferably at most 1 g/cm3, more preferably at most 0.9 g/cm3, more preferably at most 0.8 g/cm3, more preferably at most 0.7 g/cm3, more preferably at most 0.6 g/cm3, more preferably at most 0.5 g/cm3, most preferably at most 0.4 g/cm3. The composite material according to any of the preceding aspects, wherein the natural fibers have an intrinsic porosity of at least 6%, preferably at least 8%, more preferably at least 10%, more preferably at least 12%, more preferably at least 14%, more preferably at least 16%, more preferably at least 18%, more preferably at least 20%, more preferably at least 22%, more preferably at least 24%, more preferably at least 26%, more preferably at least 28%, most preferably at least 30%. The composite material according to any of the preceding aspects, wherein the matrix and the at least one flame retardant arranged at least partially within the matrix account for 30 wt% to 60 wt%, preferably 35 wt% to 55 wt%, more preferably 40 wt% to 50 wt% of a total weight of the composite material. The composite material according to any of the preceding aspects, wherein the natural fibers have a total surface energy of at least 20 mN/m, preferably at least 25 mN/m, preferably at least 30 mN/m, more preferably at least 35 mN/m. The composite material according to any of the preceding aspects, wherein the matrix, in the B-stage and/or in a substantially completely cured state of the matrix, has a total surface energy which is less than 60 mN/m, preferably less than 65 mN/m, more preferably less than 70 mN/m. The composite material according to any of the preceding aspects, wherein at least the natural fibers, more preferably all of the fibers, included in the composite material, have a total surface energy which deviates from the total surface energy of the matrix material(s), in the B-stage and/or in a substantially completely cured state of the matrix material(s), by less than 40.0 mN/m, preferably less than 30.0 mN/m, more preferably less than 25 mN/m, more preferably less than 20 mN/m, more preferably less than 18 mN/m, more preferably less than 16 mN/m, most preferably less than 15 mN/m. The composite material according to any of the preceding aspects, wherein any flame retardant included in the composite material is substantially free of halides. The composite material according to any of the preceding aspects, wherein the composite material is substantially free of halides. The composite material according to any of the preceding aspects, wherein an alkali content in any flame retardant included in the composite material is 2% or less, preferably 1 w% or less, more preferably 0.8 wt% or less, more preferably 0.5 wt% or less, more preferably 0.2 wt% or less, more preferably 0.1 wt% or less, most preferably 0.05 wt% or less, of a total weight of the flame retardant(s). The composite material according to any of the preceding aspects, wherein an alkali content in the composite material is 1 wt% or less, preferably 0.8 wt% or less, more preferably 0.5 wt% or less, more preferably 0.2 wt% or less, more preferably 0.1 wt% or less, most preferably 0.05 wt% or less, of a total weight of the composite material. The composite material according to any of the preceding aspects, wherein the natural fibers include flax fibers and/or viscose fibers, and wherein the matrix is at least partially made of furan resin. The composite material according to any of the preceding aspects, wherein the natural fibers of the composite material, preferably within one layer of prepreg, if the composite material is configured as a prepreg, have an area weight, with respect to an area of the composite material, preferably of one layer of prepreg, from 100 g/m2 to 300 g/m2, more preferably from 120 g/m2 to 270 g/m2, more preferably from 180 g/m2 220 g/m2 The composite material according to any of the preceding aspects, including a plurality of carbon fibers which are at least partially embedded within the matrix, preferably wherein the carbon fibers account for at least 30 wt%, more preferably at least 40 wt%, more preferably at least 50 wt% of a total weight of all fibers included in the composite material. The composite material according to any of the preceding aspects, including a plurality of glass fibers which are at least partially embedded within the matrix, preferably wherein the glass fibers account for at least 30 wt%, more preferably at least 40 wt%, more preferably at least 50 wt% of a total weight of all fibers included in the composite material. The composite material according to any of the preceding aspects, wherein a plurality of fibers provided in the composite material, preferably including a portion of at least the natural fibers, are configured as a crossed-fiber construction, preferably as a woven mesh, a web, a fleece, a knitting and/or a textile. The composite material according to any of the preceding aspects, wherein the composite material is configured to pass the heat release rate (OSU) test. The composite material according to any of the preceding aspects, wherein the composite material is configured to pass the low spread of flame test according to IMO 2010 FTPC Part 5 as referred to in the Maritime Equipment Directive 2014/90/EU of July 23^rd 2014 for class 3.18a. The composite material according to any of the preceding aspects, wherein the flame retardant(s) included in the matrix is/are substantially free of halogenides, more preferably free of organic halogenides. The composite material according to any of the preceding aspects, wherein the flame retardant(s) included in the matrix is/are free of boron, its salts, and compounds. The composite material according to any of the preceding aspects, wherein the flame retardant(s) included in the natural fibers is/are substantially free of halogenides, more preferably free of organic halogenides. The composite material according to any of the preceding aspects, wherein the flame retardant(s) included in the natural fibers is/are free of boron, its salts, and compounds. The composite material according to any of the preceding aspects, wherein the flame retardant(s) included in the natural fibers include(s) at least one organic phosphorus compound. A sandwich-structured composite including at least one core element which is at least partially sandwiched between at least two facings, wherein at least one of the facings, preferably both facings, include(s) at least one layer of a fiber-reinforced composite material according to any of the preceding aspects. A component, preferably a paneling element, preferably a moulded part, for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft, wherein the component is at least partially made of a fiber-reinforced composite material according to any of aspects 1 to 65 and/or a sandwich-structured composite according to aspect 66, preferably wherein the fiber- reinforced composite material(s) is/are substantially completely cured. A vehicle, preferably a powered vehicle, preferably a powered aircraft and/or a powered watercraft, wherein the vehicle includes a component, preferably a component according to aspect 67, preferably a paneling element, preferably a moulded part, wherein the component is arranged in an interior of the vehicle. A method for manufacturing a composite material, preferably a composite material according to any of aspects 1 to 65, the method including the following steps:

(a) providing at least one matrix made of a biobased material;

(b) providing a plurality of fibers including natural fibers; (c) optionally applying at least one flame retardant to the matrix, preferably such that the flame retardant is arranged at least partially within the matrix;

(d) optionally applying at least one flame retardant to at least a section of at least the natural fibers, preferably such that the at least one flame retardant is arranged in at least a section of the natural fibers; and

(e) embedding the natural fibers at least partially in the matrix. The method according to aspect 69, wherein the matrix includes at least one thermoset, preferably a thermosetting resin, preferably substantially based on polyfurfuryl alcohol (PFA) and preferably wherein, after step (e), the matrix is cured. The method according to aspect 69 or 70, wherein steps (c) and (d) are performed before step (e). The method according to any of aspects 69 to 71, wherein the natural fibers include organic fibers and/or inorganic fibers. The method according to any of aspects 69 to 72, wherein the natural fibers include plant-based fibers. The method according to any of aspects 69 to 73, wherein the natural fibers only include plant-based fibers. The method according to any of aspects 69 to 74, wherein the natural fibers include flax fibers, preferably only flax fibers. The method according to any of aspects 69 to 75, wherein the natural fibers include viscose fibers, preferably only viscose fibers. The method according to any of aspects 69 to 76, wherein, in step (d), the natural fibers are impregnated by the flame retardant. The method according to any of aspects 69 to 77, wherein, in step (d), the natural fibers are substantially saturated with the flame retardant.

79. The method according to any of aspects 69 to 78, wherein, in step (c), at least one first flame retardant is applied to the matrix such that the flame retardant is arranged at least partially within the matrix and, in step (d), at least one second flame retardant is applied to at least a section of the natural fibers, wherein the first flame retardant and the second flame retardant are different.

80. The method according to aspect 79, wherein the first flame retardant and the second flame retardant differ in one or more of the following properties: a solubility, a nitrogen content, a phosphorus content, a boron content, an aluminum content and a concentration of the respective flame retardant within the matrix, and the natural fibers, respectively.

Fig. 1 shows, in a schematic top view, a composite material according to an embodiment of the present invention;

Fig. 2 shows, in a schematic side view, the composite material of Fig. 1;

Fig. 3 shows, in a schematic and perspective view, a component made at least partially from the composite material shown in Figs. 1 and 2;

Fig. 4 shows, in a schematic and perspective view, an aircraft with an interior in which the component shown in Fig. 3 is arranged.

Figs. 1 and 2 show a composite material 10 according to an embodiment of the present invention. The composite material 10 includes a matrix 12 made substantially of a biobased material and a plurality of natural fibers 14 which are at least partially embedded within the matrix 12. The matrix 12 includes at least one flame retardant 16 arranged at least partially within the matrix 12. The natural fibers 14 include at least one flame retardant 18 arranged in at least a section of the natural fibers 14. The natural fibers 14 may be impregnated and/or substantially saturated by the flame retardant 18.

Preferably, the natural fibers 14 include viscose fibers and/or flax fibers. However, any natural fibers may be employed in the composite material 10, such as one or more of the following: viscose fibers, flax fibers, hemp fibers, bagasse fibers, bamboo fibers, kenaf fibers, jute fibers, ramie fibers, abaca fibers, sisal fibers, coir fibers, oil palm fibers, pineapple fibers and curaua fibers

According to the embodiment of Figs. 1 and 2, the composite material 10 is configured as a prepreg, e.g., as one or more sheets and/or one or more strips of prepreg. In the prepreg, the matrix 12, more specifically one or more materials of the matrix 12, is partially cured, e.g., to allow easier handling of the prepreg, e.g., to form or mould one or more parts using the prepregs. Such a partially cured state of the matrix 12 is often referred to as a B-stage of the matrix 12. To prevent further curing of the matrix 12, prepregs are often stored in cooled areas since heat may initiate and/or accelerate curing of the matrix 12. To prevent further curing, prepregs are often placed in a freezer at 0 °F. In a frozen state, the matrix 12 of the prepreg material may remain in the B-stage. Further curing of the matrix 12 is usually initiated when the material is removed from the freezer and/or heated.

The matrix 12 may be configured to cure, e.g., fully cure, at room temperature. Alternatively, the matrix 12 may be configured such that the matrix 12 must be heated to partially and/or fully cure. Alternatively, or additionally, the matrix 12 may be configured to be cured based on one or more chemical reactions to cure, such as in the case of a thermoset which may be included in the matrix 12 of the composite material described herein.

The prepreg may be configured to be moulded to a one or more components for an interior a vehicle, such as one or more paneling elements for the interior of a vehicle, as shown in Figs. 3 and 4 and described further below. Components which are moulded purely from composite materials, such the as the composite material 10 described herein, may have a relatively high tensile strength, e.g., at least in a direction along the fibers.

Alternatively, or additionally, the composite material 10 may be configured for use in sandwich-structured composites, e.g., as one or more layers of such sandwich-structured composites. The sandwich-structured composite may include one or more layers, preferably at least two layers, preferably at least two outer layers, which sandwich a core element.

The matrix 12 may include at least one thermoset, preferably a thermosetting resin, preferably including polyfurfuryl alcohol (PFA). The natural fibers 14 may be at least partially made of plant-based fibers. In this case, the flame retardant 18 arranged in at least a section of the natural fibers 14 may include phosphorus (P). A ratio of carbon (C) to phosphorus (P) in the plant-based fibers may range from 1 to 200. Alternatively, or additionally, the flame retardant 18 arranged in at least a section of the natural fibers 14 may include nitrogen (N). A ratio of carbon (C) to nitrogen (N) in the plant-based fibers may range from 5 to 40.

Preferably, the natural fibers 14 are first treated with the flame retardant 18 before being embedded in the matrix 12. Thus, the natural fibers 14 may be soaked, e.g., highly, or completely, saturated in flame retardant 18. This may provide a relatively high concentration of flame retardant 18 in the natural fibers 14, which may increase the flame retardant properties of the composite material 10, e.g., compared with applying the flame retardant 18 after the natural fibers 14 have been embedded in the matrix 12 and/or applying the flame retardant 18 and the matrix 12 simultaneously to the natural fibers 14, e.g., by applying a matrix 12 which includes a flame retardant therein to the natural fibers 14.

The composite material 10 may be configured to be used in a paneling element for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft.

Fig. 3 shows a component 110 made at least partially from the composite material 10 shown in Figs. 1 and 2. The component 110 may be any part or structure, preferably a paneling element, preferably a moulded part, configured for use in an interior of a vehicle.

Fig. 4 shows an aircraft 150 with an interior 152 in which the component 110 shown in Fig. 3 is arranged. Alternatively, the aircraft 150 may be any type of vehicle, preferably a powered vehicle, e.g., a watercraft or a spacecraft, which has an interior in which the component 110 may be arranged.

Claims

Claims A fiber-reinforced composite material, including: at least one matrix made of a biobased material; and a plurality of natural fibers which are at least partially embedded within the matrix; wherein the matrix includes at least one flame retardant arranged at least partially within the matrix, and wherein the natural fibers include at least one flame retardant arranged in at least a section of the natural fibers. The composite material according to claim 1, wherein the natural fibers include natural organic fibers and/or natural inorganic fibers. The composite material according to claim 1 or 2, wherein the natural fibers include plant-based fibers, preferably only plant-based fibers. The composite material according to any of the preceding claims, wherein the flame retardant arranged in at least a section of the natural fibers has been applied to at least a portion of the natural fibers before the natural fibers have been embedded at least partially in the matrix. The composite material according to any of the preceding claims, wherein the natural fibers include one or more of the following: viscose fibers, flax fibers, hemp fibers, bagasse fibers, bamboo fibers, kenaf fibers, jute fibers, ramie fibers, abaca fibers, sisal fibers, coir fibers, oil palm fibers, pineapple fibers and curaua fibers. The composite material according to any of the preceding claims, wherein the natural fibers include flax fibers, preferably only flax fibers. The composite material according to any of the preceding claims, wherein the natural fibers include viscose fibers, preferably only viscose fibers. The composite material according to any of the preceding claims, wherein the fibers included in the composite material only include viscose fibers and flax fibers. The composite material according to any of the preceding claims, wherein the matrix includes at least one thermoset, preferably a thermosetting resin, preferably including polyfurfuryl alcohol (PFA). The composite material according to any of the preceding claims, wherein at least the natural fibers are impregnated by the flame retardant. The composite material according to any of the preceding claims, wherein the flame retardant arranged in at least a section of the natural fibers accounts for 1.5 wt% to 30 wt%, preferably 1.5 wt% to 25 wt%, more preferably 1.5 wt% to 20 wt%, more preferably 1.5 wt% to 15 wt%, more preferably 2 wt% to 10 wt%, more preferably 2.5 wt% to 7 wt%, more preferably 3.0 wt% to 8.0 wt%, more preferably 3.0 wt% to 7.0 wt%, more preferably 4.0 wt% to 7.0 wt%, of a total weight of the natural fibers. The composite material according to any of the preceding claims, wherein the natural fibers are at least partially made of plant-based fibers, wherein the flame retardant included in the plant-based fibers includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) in the plant-based fibers, including the flame retardant, ranges from 10 to 200, preferably from 10 to 140, more preferably from 20 to 110, more preferably 20 to 90, more preferably 30 to 90, most preferably from 80 to 90. The composite material according to any of the preceding claims, wherein the natural fibers are at least partially made of plant-based fibers, wherein the flame retardant included in the plant-based fibers includes nitrogen (N), wherein a ratio of carbon (C) to nitrogen (N) in the plant-based fibers, including the flame retardant, ranges from 5 to 40, preferably from 10 to 40, more preferably from 10 to 30, more preferably from 10 to 25, most preferably from 15 to 25. The composite material according to any of the preceding claims, wherein the natural fibers are at least partially made of plant-based fibers, wherein the flame retardant included in the plant-based fibers includes a P-N (nitrogen-phosphorus) type flame retardant, wherein a ratio of phosphorus (P) to nitrogen (N) in the plant-based fibers (including the flame retardant) ranges from 0.2 to 0.6, more preferably from 0.2 to 0.5, preferably from 0.2 to 0.45, more preferably from 0.25 to 0.35, most preferably from 0.27 to 0.33. The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix accounts for 10 wt% to 40 wt%, more preferably 15 wt% to 35 wt%, most preferably 20 wt% to 30 wt% of a total weight of the matrix. The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix is a P type, or preferably a P-N (nitrogen-phosphorus) type, flame retardant, wherein a phosphorus content in the matrix accounts for at least 1 wt%, more preferably from 1 wt% to 5 wt%, more preferably from 1.5 wt% to 4 wt%, more preferably from 1.9 wt% to 3.5 wt%, most preferably 1.9 wt% to 2.9 wt% of a total weight of the matrix. The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix is an N type flame retardant, preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a nitrogen content in the matrix accounts for at least 1 wt%, more preferably from 1 wt% to 7 wt%, more preferably from 1 wt% to 6 wt%, more preferably from 2 wt% to 5 wt%, more preferably from 2 wt% to 4 wt%, most preferably from 3 wt% to 4 wt% of a total weight of the matrix. The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix is a P type flame retardant, preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a ratio of a phosphorus content to a nitrogen content in the matrix is 0.1 to 3, preferably 0.1 to 2, more preferably 0.3 to 1.25, more preferably 0.5 to 0.95, more preferably 0.6 to 0.85, more preferably 0.65 to 0.8, most preferably 0.7 to 0.75. The composite material according to any of the preceding claims, wherein the flame retardant arranged in at least a section of the natural fibers is an N type flame retardant, preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a nitrogen content within the natural fibers accounts for at least 0.5 wt%, preferably 0.5 wt% to 7 wt%, more preferably 0.5 to 6 wt%, more preferably 0.5 to 5 wt%, more preferably 1 wt% to 4.0 wt%, more preferably 1.5 wt% to 4.0 wt%, most preferably 1.5 wt% to 3.5 wt% of a total weight of the natural fibers. The composite material according to any of the preceding claims, wherein the flame retardant arranged in at least a section of the natural fibers is a P type flame retardant, preferably a P-N (nitrogen-phosphorus) type flame retardant, wherein a phosphorus content within the natural fibers accounts for at least 0.2 wt%, preferably 0.2 wt% to 3 wt%, more preferably 0.2 wt% to 2.0 wt%, more preferably 0.2 to 1.5 wt%, more preferably 0.4 wt% to 1.3 wt%, more preferably 0.4 wt% to 0.7 wt%, most preferably 0.4 wt% to 0.6 wt% of a total weight of the natural fibers. The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix includes phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) within the matrix ranges from 5 to 50, preferably 10 to 40, more preferably 15 to 35, more preferably 20 to 30, more preferably 20 to 25, most preferably 21.5 to 23.5. The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix includes nitrogen (N), wherein a ratio of carbon (C) to nitrogen (N) within the matrix ranges from 3 to 8, preferably 6 to 40, more preferably 12.5 to 20, more preferably 14.5 to 18.5, most preferably 15.5 to 17.5. The composite material according to any of the preceding claims, wherein the composite material includes a total content of flame retardant of at least 4 wt%, preferably from 4 wt% to 40 wt%, more preferably from 5 wt% to 30 wt%, more preferably from 5 wt% to 20 wt%, most preferably from 10 wt% to 20 wt%, of a total weight of the composite material. The composite material according to any of the preceding claims, wherein the flame retardant(s) arranged in the composite material include(s) nitrogen (N), wherein a nitrogen (N) content of the composite material is between 1 wt% to 10 wt%, preferably 1 wt% to 5 wt%, more preferably 1.5 wt% to 4 wt%, more preferably 1.9 wt% to 3 wt%, more preferably 2.3 wt% to 3.0 wt%, most preferably 2.3 wt% to 2.5 wt% of a total weight of the composite material. The composite material according to any of the preceding claims, wherein the flame retardant arranged in the composite material include(s) nitrogen (N) and phosphorus (P), wherein a ratio of phosphorus (P) to nitrogen (N) in the composite material is from 0.3 to 1, preferably 0.3 to 0.8, more preferably from 0.35 to 0.7, more preferably from 0.4 to 0.7, more preferably from 0.45 to 0.65, more preferably from 0.50 to 0.60, most preferably from 0.52 to 0.56. The composite material according to any of the preceding claims, wherein the flame retardant arranged in the composite material include(s) nitrogen (N), wherein a ratio of carbon (C) to nitrogen in the composite material is from 10 to 50, preferably from 10 to 40, more preferably from 10 to 30, more preferably from 15 to 30, more preferably from 15 to 25, more preferably from 17.3 to 22.8, more preferably from 17.5 to 20.5, more preferably from 18.0 to 19.0, most preferably from 18.2 to 18.8. The composite material according to any of the preceding claims, wherein the flame retardant(s) in the composite material include(s) phosphorus (P), wherein a ratio of carbon (C) to phosphorus (P) in the composite material is from 10 to 85, preferably from 10 to 70, more preferably from 20 to 60, more preferably from 20 to 50, more preferably from 20 to 40, more preferably from 30 to 40, more preferably from 32 to 35.5, most preferably from 33.5 to 35.5. The composite material according to any of the preceding claims, wherein the flame retardant(s) arranged in the composite material include(s) phosphorus (P), wherein a phosphorus (P) content in the composite material is between 0.5 wt% to 10 wt%, more preferably 0.5 wt% to 5 wt%, more preferably 0.9 wt% to 4 wt%, more preferably 1 wt% to 3 wt%, more preferably 1.0 wt% to 3.0 wt%, more preferably 1.0 wt% to 2.5 wt%, most preferably 1.0 wt% to 2.0 wt% of a total weight of the composite material The composite material according to any of the preceding claims, wherein the flame retardant arranged at least partially within the matrix and/or the flame retardant arranged in at least a section of the natural fibers include(s) one or more of the following: a salt formed from an organic amine compound and an organic phosphonic acid compound. The composite material according to any of the preceding claims, wherein the composite material is free of a bonding agent for promoting bonding between the matrix and the natural fibers. The composite material according to any of the preceding claims, wherein the natural fibers and/or the matrix, preferably the composite material, is/are substantially free of volatile organic compounds (VOC). The composite material according to any of the preceding claims, wherein the composite material has a tensile ultimate strength of at least 300 MPa, more preferably at least 400 MPa, more preferably at least 450 MPa, more preferably at least 500 MPa, more preferably at least 600 MPa, more preferably at least 700 MPa, more preferably at least 800 MPa, more preferably at least 900 MPa, more preferably at least 1000 MPa, more preferably at least 1100 MPa, more preferably at least 1200 MPa, more preferably at least 1300 MPa, more preferably at least 1400 MPa, most preferably at least 1500 MPa. The composite material according to any of the preceding claims, wherein at least 10 wt%, preferably at least 15 wt%, preferably at least 20 wt%, more preferably at least 25 wt%, more preferably at least 30 wt%, more preferably at least 35 wt%, more preferably at least 40 wt%, more preferably at least 45 wt%, more preferably at least 50 wt%, more preferably at least 55 wt%, more preferably at least 60 wt%, more preferably at least 65 wt%, more preferably at least 70 wt%, more preferably at least 75 wt%, most preferably at least 80 wt%, of the natural fibers is made of natural organic material. The composite material according to any of the preceding claims, wherein the matrix is at least partially made of organic material, preferably wherein at least 10 wt%, more preferably at least 15 wt%, more preferably at least 20 wt%, more preferably at least 25 wt%, more preferably at least 30 wt%, more preferably at least 35 wt%, more preferably at least 40 wt%, more preferably at least 45 wt%, more preferably at least 50 wt%, more preferably at least 55 wt%, more preferably at least 60 wt%, more preferably at least 65 wt%, more preferably at least 70 wt%, more preferably at least 75 wt%, most preferably at least 80 wt%, of the matrix is made of organic material. The composite material according to claim 34, wherein the carbon (C) included in the matrix stems at least partially from one or more raw plant materials which were processed to form the matrix, preferably wherein at least 40%, more preferably at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90%, most preferably at least 95% of the carbon (C) included in the matrix stems from one or more raw plant materials which were processed to form the matrix. The composite material according to any of the preceding claims, wherein the composite material is configured to be used in a paneling element for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft. The composite material according to any of the preceding claims, wherein the composite material is configured for use in fire hazardous environments, preferably in a powered vehicle, preferably a powered aircraft and/or a powered watercraft. The composite material according to any of the preceding claims, wherein the composite material is configured to pass the vertical burn test. The composite material according to any of the preceding claims, wherein the composite material is configured to pass the fire testing according to the Spread of Flame Test according to the International Maritime Organization (IMO) 2010 FTP Code Part 5. The composite material according to any of the preceding claims, wherein the matrix includes at least one first flame retardant arranged at least partially within the matrix and the natural fibers include at least one second flame retardant arranged in at least a section of the natural fibers, wherein the first flame retardant and the second flame retardant are different. The composite material according to any of the preceding claims, wherein the first flame retardant and the second flame retardant differ in one or more of the following properties: a solubility, a nitrogen content, a phosphorus content, a boron content, an aluminum content, a nitrogen to phosphorus ratio, and a concentration of the respective flame retardant within the matrix and the natural fibers, respectively. The composite material according to claim 40 or 41, wherein the first flame retardant is substantially soluble in the matrix, in an A-stage of the matrix, and the second flame retardant is substantially soluble in water. The composite material according to any of claims 40 to 42, wherein the first flame retardant includes particulates and/or powder which can form a suspension in the matrix, in an A-stage of the matrix, and the second flame retardant is substantially soluble in water. The composite material according to any of the preceding claims, wherein the natural fibers have an intrinsic density of at most 2 g/cm3, preferably at most 1.9 g/cm3, more preferably at most 1.8 g/cm3, more preferably at most 1.7 g/cm3, more preferably at most 1.6 g/cm3, more preferably at most 1.5 g/cm3, more preferably at most 1.4 g/cm3, more preferably at most 1.3 g/cm3, more preferably at most 1.2 g/cm3, more preferably at most 1.1 g/cm3, more preferably at most 1 g/cm3, more preferably at most 0.9 g/cm3, more preferably at most 0.8 g/cm3, more preferably at most 0.7 g/cm3, more preferably at most 0.6 g/cm3, more preferably at most 0.5 g/cm3, most preferably at most 0.4 g/cm3. The composite material according to any of the preceding claims, wherein the natural fibers have an intrinsic porosity of at least 6%, preferably at least 8%, more preferably at least 10%, more preferably at least 12%, more preferably at least 14%, more preferably at least 16%, more preferably at least 18%, more preferably at least 20%, more preferably at least 22%, more preferably at least 24%, more preferably at least 26%, more preferably at least 28%, most preferably at least 30%. The composite material according to any of the preceding claims, wherein the matrix and the at least one flame retardant arranged at least partially within the matrix account for 30 wt% to 60 wt%, preferably 35 wt% to 55 wt%, more preferably 40 wt% to 50 wt% of a total weight of the composite material. The composite material according to any of the preceding claims, wherein the natural fibers have a total surface energy of at least 20 mN/m, preferably at least 25 mN/m , preferably at least 30 mN/m, more preferably at least 35 mN/m. The composite material according to any of the preceding claims, wherein the matrix, in the B-stage and/or in a substantially completely cured state of the matrix, has a total surface energy which is less than 60 mN/m , preferably less than 65 mN/m, more preferably less than 70 mN/m. The composite material according to any of the preceding claims, wherein at least the natural fibers, more preferably all of the fibers, included in the composite material, have a total surface energy which deviates from the total surface energy of the matrix material(s), in the B-stage and/or in a substantially completely cured state of the matrix material(s), by less than 40.0 mN/m, preferably less than 30.0 mN/m, more preferably less than 25 mN/m, more preferably less than 20 mN/m, more preferably less than 18 mN/m, more preferably less than 16 mN/m, most preferably less than 15 mN/m. The composite material according to any of the preceding claims, wherein any flame retardant included in the composite material is substantially free of halides. The composite material according to any of the preceding claims, wherein the composite material is substantially free of halides, preferably of organic halides. The composite material according to any of the preceding claims, wherein an alkali content in any flame retardant included in the composite material is 1 w% or less, preferably 0.8 wt% or less, more preferably 0.5 wt% or less, more preferably 0.2 wt% or less, more preferably 0.1 wt% or less, most preferably 0.05 wt% or less, of a total weight of the flame retardant(s). The composite material according to any of the preceding claims, wherein an alkali content in the composite material is 1 wt% or less, preferably 0.8 wt% or less, more preferably 0.5 wt% or less, more preferably 0.2 wt% or less, more preferably 0.1 wt% or less, most preferably 0.05 wt% or less, of a total weight of the composite material. The composite material according to any of the preceding claims, wherein the natural fibers include flax fibers and/or viscose fibers, and wherein the matrix is at least partially made of furan resin. The composite material according to any of the preceding claims, wherein the natural fibers of the composite material, preferably within one layer of prepreg, if the composite material is configured as a prepreg, have an area weight, with respect to an area of the composite material, preferably of one layer of prepreg, from 100 g/m2 to 300 g/m2, more preferably from 120 g/m2 to 270 g/m2, more preferably from 180 g/m2 220 g/m2 The composite material according to any of the preceding claims, including a plurality of carbon fibers which are at least partially embedded within the matrix, preferably wherein the carbon fibers account for at least 30 wt%, more preferably at least 40 wt%, more preferably at least 50 wt% of a total weight of all fibers included in the composite material. The composite material according to any of the preceding claims, including a plurality of glass fibers which are at least partially embedded within the matrix, preferably wherein the glass fibers account for at least 30 wt%, more preferably at least 40 wt%, more preferably at least 50 wt% of a total weight of all fibers included in the composite material. The composite material according to any of the preceding claims, wherein a plurality of fibers provided in the composite material, preferably including a portion of at least the natural fibers, are configured as a crossed-fiber construction, preferably as a woven mesh, a web, a fleece, a knitting and/or a textile. The composite material according to any of the preceding claims, wherein the composite material is configured to pass the heat release rate (OSU) test. The composite material according to any of the preceding claims, wherein the composite material is configured to pass the low spread of flame test according to IMO 2010 FTPC Part 5 as referred to in the Maritime Equipment Directive 2014/90/EU of July 23^rd 2014 for class 3.18a. The composite material according to any of the preceding claims, wherein the flame retardant(s) included in the matrix is/are substantially free of halogenides, more preferably free of organic halogenides. The composite material according to any of the preceding claims, wherein the flame retardant(s) included in the matrix is/are free of boron, its salts, and compounds. The composite material according to any of the preceding claims, wherein the flame retardant(s) included in the natural fibers is/are substantially free of halogenides, more preferably free of organic halogenides. The composite material according to any of the preceding claims, wherein the flame retardant(s) included in the natural fibers is/are free of boron, its salts, and compounds. The composite material according to any of the preceding claims, wherein the flame retardant(s) included in the natural fibers include(s) at least one organic phosphorus compound. A sandwich-structured composite including at least one core element which is at least partially sandwiched between at least two facings, wherein at least one of the facings, preferably both facings, include(s) at least one layer of a fiber-reinforced composite material according to any of the preceding claims. A component, preferably a paneling element, preferably a moulded part, for use in an interior of a vehicle, preferably in a powered vehicle, preferably in a powered aircraft and/or in a powered watercraft, wherein the component is at least partially made of a fiber-reinforced composite material according to any of claims 1 to 65 and/or a sandwich-structured composite according to claim 66, preferably wherein the fiber- reinforced composite material(s) is/are substantially completely cured. A vehicle, preferably a powered vehicle, preferably a powered aircraft and/or a powered watercraft, wherein the vehicle includes a component, preferably a component according to claim 67, preferably a paneling element, preferably a moulded part, wherein the component is arranged in an interior of the vehicle. A method for manufacturing a fiber-reinforced composite material, preferably a fiber- reinforced composite material according to any of claims I to 65, the method including the following steps:

(a) providing at least one matrix made of a biobased material;

(b) providing a plurality of fibers including natural fibers;

(d) applying at least one flame retardant to at least a section of at least the natural fibers; and

(e) embedding the natural fibers at least partially in the matrix. The method according to claim 69, wherein the matrix includes at least one thermoset, preferably a thermosetting resin, preferably substantially based on polyfurfuryl alcohol (PFA) and preferably wherein, after step (e), the matrix is cured. The method according to claim 69 or 70, wherein steps (c) and (d) are performed before step (e). The method according to any of claims 69 to 71, wherein the natural fibers include organic fibers and/or inorganic fibers. The method according to any of claims 69 to 72, wherein the natural fibers include plant-based fibers. The method according to any of claims 69 to 73, wherein the natural fibers only include plant-based fibers. The method according to any of claims 69 to 74, wherein the natural fibers include flax fibers, preferably only flax fibers. The method according to any of claims 69 to 75, wherein the natural fibers include viscose fibers, preferably only viscose fibers. The method according to any of claims 69 to76, wherein, in step (d), the natural fibers are impregnated by the flame retardant. The method according to any of claims 69 to 77, wherein, in step (d), the natural fibers are substantially saturated with the flame retardant. The method according to any of claims 69 to 78, wherein, in step (c), at least one first flame retardant is applied to the matrix such that the flame retardant is arranged at least partially within the matrix and, in step (d), at least one second flame retardant is applied to at least a section of the natural fibers, wherein the first flame retardant and the second flame retardant are different. The method according to claim 79, wherein the first flame retardant and the second flame retardant differ in one or more of the following properties: a solubility, a nitrogen content, a phosphorus content, a boron content, an aluminum content, and a concentration of the respective flame retardant within the matrix and the natural fibers, respectively.