EP4590886A1

EP4590886A1 - Method of extraction of fibres

Info

Publication number: EP4590886A1
Application number: EP23783528.5A
Authority: EP
Inventors: Mohamad MIDANI; Ahmed HASSANIN; Tamer Hamouda
Original assignee: Scaleup Innovations Holdings Ltd
Current assignee: Scaleup Innovations Holdings Ltd
Priority date: 2022-09-22
Filing date: 2023-09-22
Publication date: 2025-07-30
Also published as: GB202213838D0; MX2025003468A; CN119998504A; GB2616691B; GB2616691A8; WO2024062440A1; GB2616691A

Abstract

A method of obtaining long flexible textile fibres from species of palm trees. The method includes the combined steps of treating stems to delignify them by application of an alkali solution wherein the alkali solution may be a sodium hydroxide solution. Followed by scraping the treated stems to mechanically remove the non-cellulosic matrix and fibrillate the fibre vascular bundles by application of a blunt scraper blade. The step may comprise soaking stems in an alkali solution at a temperature t where t is in the range of: t = -4.82(c*d) + 92.3 °C +/- 12.5°C, where c is the concentration of sodium hydroxide in %, or pH equivalent, and d the duration of treatment in hours.

Description

METHOD OF EXTRACTION OF FIBRES

Field of the Invention

This disclosure relates to a method of extraction of fibres and more particularly, but not exclusively, the invention relates to extraction of long textile fibres from palm midribs and spadix stems, such as the fibres from date palms (Phoenix dactylifera).

Background

Date palms are mainly cultivated in the Middle East and North African regions. Typically, global harvests exceed 1 million hectares. The estimated annual by-products of pruning date palms globally are around 5 million tons (air dry weight), in the form of midribs, spadix stems, leaflets and leaf sheath. These materials are often treated as agricultural waste.

Previous attempts to extract fibres from date palm midribs and spadix stems were limited to milling them into small particles with a high percentage of non-cellulosic impurities. These tended to be used in the manufacture of worktops and building panels such as particle boards or (MDF) or as fillers in synthetic plastics material.

Some of these are described in the documents mentioned below.

Prior Art

US patent US 10 767 267 (United Arab Emirates University).

International patent application WO 2020/139088 (Sultan Qaboos University).

Canadian patent application CA 2 504 227 (Soil Sub Technologies PTY Ltd).

US patent US 10 655 009 (United Arab Emirates University).

Russian patent application SU 620517 (TSNII PROMY LUBYANYKH VOLOKON) describes a method of obtaining fibres from bast which uses a scouring process to produce a fibre with better spinnability. None of these attempts were capable of extracting long textile grade fibres.

An object of the present invention is to valorize large quantities of agricultural residues generated by palm, particularly date palm, plantations and to extract long textile fibres from the midribs and spadix stems.

Summary of Invention

According to a first aspect of the present invention there is provided a method of obtaining fibres from species of palm trees, the method including the steps of a) treating stems to delignify them by application of an alkali solution and b) scraping the treated stems to mechanically remove non-cellulosic matrix.

Ideally fibre vascular bundles are also fibrillated, for example by application of a blunt scraper blade.

The present invention mechanically removes the non-cellulosic matrix and fibrillates the fibre vascular bundles by extraction, to clean the fibres and improve spinnability using a combined chemical and mechanical method.

In one embodiment the invention is used to extract fibres from date palm leaf stalks. The date palm leaf stalk (midrib) is primarily composed of coarse vascular fibre bundles across the entire cross section of the stalk and embedded in a matrix of lignin and hemicellulose. Palms are classified as monocotyledons which consist of numerous fibre vascular bundles in varying sizes. However, it will be appreciated that the method may be used with other types of palms, as described below.

Bast fibres are dicotyledons and are composed of pure fibre bundles. They tend to be of a uniform in size. Due to these inherent structural differences between leaf and bast fibres, the technical challenges associated with extracting vascular bundles are therefore significantly different from extracting pure fibre bundles.

In some embodiments the alkali solution is a sodium hydroxide solution.

Preferably the method includes the steps of soaking stems in an alkali solution at a temperature t where t is in the range of t = -4.82 (c x d) + 92.3 °C +/- 12.5°C, where c is the concentration of sodium hydroxide in %, or pH equivalent, and d is the duration of treatment in hours. Followed by the steps of scraping the stems by the application of a blunt scraper blade.

In some embodiments the method step comprises soaking stem material in an alkali solution at a temperature t where t is in the range of t = -4.82(c x d) + 92.3 °C +/- 6°C.

Optionally the method includes an initial step c) of separating the leaflets from palm fronds.

In some embodiments the method includes a prior step d) peeling the outer layer of the palm stems to remove the waterproof wax and pectin layer that prevent the treatment.

The method may include a further prior step of e) of slicing the stems longitudinally to reduce their thickness and ensure uniform treatment across the stems thickness.

In the claims the term “stem” includes palm midribs and spadix stems.

According to a second aspect of the invention there is provided a method of obtaining fibres from species of palm trees, the method includes the steps of: soaking fibre stems in a water pool at an ambient temperature 20 °C to 45 °C.

Soaking may be performed in direct sun or in shade and may continue for a period of between 1 and 16 weeks.

According to a third aspect of the invention there is provided a method of obtaining fibres from species of palm trees comprising the steps of: placing midribs/spadix slices in hot water at temperature from 80 °C to 100 °C in normal atmospheric pressure for a duration of between 3 to 8 hours.

Optionally midribs/spadix slices are placed in a pressurized vessel at a temperature which is between 100°C to 120°C at a pressure 0 - 1 bar for a duration between 1 to 3 hours.

Preferably the midribs/spadix slices are peeled prior to slicing.

According to a fourth aspect of the invention there is provided a fibrous product derived using the aforementioned methods.

Fibrous products produced according to the method may be used to make or incorporated in, a myriad different items or products, including: an item of clothing or footwear: a sheet of flexible material; items for use in automotive or construction, (such as boards or insulation panels) or rope or twine.

Brief Description of Drawings

The invention will now be described with reference to examples and the following Figures of which:

Figure 1 shows date palm midribs (above) and spadix stems (below) respectively;

Figure 2 shows three SEM micrographs indicating building blocks of the date palm midrib;

Figure 3a shows damage and breakage to fibrils due to nonoptimized treatment;

Figure 3b shows pure undamaged midrib and spadix fibrils resulting from optimization of process steps;

Figures 4 and 5 show examples of resulting fibres after application of an extraction method;

Figure 6 shows a diagrammatical representation of method steps according to one example of the invention;

Figure 7 shows an image of an example of a gypsum plaster block reinforced with treated date palm midrib fibre;

Figure 8 shows an image of one example of a date palm midrib moulded pulp food bowl or dish;

Figure 9 shows an image of an insulation batt formed from treated date palm midrib fibres; and

Figure 10 shows an image of an example of a composite panel formed from treated date palm midrib and spadix stem fibres.

Detailed Description of Preferred Embodiments

Figures 1 shows date palm midribs (above) and spadix (below) stems respectively. Date palm midrib and spadix fibres are considered leaf fibres similar to sisal, abaca, pineapple, and banana fibres. Generally, leaf fibres are monocotyledons which consist of numerous fibre vascular bundles in varying sizes. Most fibre bundles are circular or oval with single or multiple vascular voids and they are composed of elemental fibrils which can have multiple cell walls and a central lumen as shown in Figure 2, which shows SEM micrographs showing the building blocks of the date palm midrib.

Conventional fibre extraction routes used with other leaf fibres (sisal, banana, abaca or pineapple), such as scraping-washing-brushing, cannot be applied in the case of extracting fibres from date palm midrib and spadix stems. This is because the midrib and spadix stem are thicker and have lower moisture content and they are covered with a hard layer of wax and pectin. Therefore, any attempt to directly scrape them will result in crushing rather than extraction.

Moreover, there are two major challenges associated with extracting long textile fibres from the date palm midribs and spadix stems. Firstly, the vascular fibre bundles are embedded inside the midrib or the spadix stem and surrounded by a matrix of complex natural binder made up of lignin and hemicellulose, which makes it difficult to extract the pure fibres without breaking or damaging them. Secondly, the vascular fibre bundles are coarse and hollow, and they do not have enough flexibility to be processed into any textile form. The fibres therefore tend to break whenever they are bent or twisted.

In exemplar methodology is provided a process to delignify and fibril late the fibre vascular bundles into pure long and flexible elemental fibrils or smaller bundles, without causing any damage to the fibrils during extraction.

Methodology

Initial Preparation

In an initial step the leaflets are separated from the green freshly cut date palm fronds either manually by hand, knife, or by using a mechanized system with blades to peel off the leaflets to obtain the midribs, which are then bundled for further processing. In case of the spadix stems, top twigs are cut from the green fresh spadices using knife, manual saw or mechanized saw.

Peeling

Peeling of outer wax and pectin layer surrounding the midrib and spadix stem is an important step to ensure effective extraction. Because the wax and pectin layers act as a waterproof membrane that prevents any downstream wet treatments penetrating and reacting with the inner core of the midrib and spadix.

The peeling may be performed mechanically by scraping or stripping blades, or by abrasive grinding rollers or papers or wire brush rollers or drums. Peeling may also be performed thermally using singeing in which a direct flame source is used to burn off the wax and pectin layer. Alternatively, a high intensity heat source, such as laser, may be used.

Peeling can be achieved chemically using solvents, including methanol, hydrochloric acid and other commercial solvents used in wax and pectin dissolution.

Slicing

Slicing is the process of reducing the thickness of the midrib or spadix stem and splitting them into smaller longitudinal sticks with regular or irregular cross-sectional areas, ideally which do not exceed 3 cm². The slicing process is very important to ensure that downstream wet treatment will have a uniform effect and to avoid shell-treatment issues, in which the outer shell of the sticks is treated, while the inner core remains untreated.

Slicing can be performed manually using a knife or can be performed using a mechanized system, in which the midrib or spadix stem is fed into a machine with conveying rollers that force the stems to emerge through the blades of a slicing die with the predefined cross-sectional shape and size. Slicing can also be performed by using mechanized pressure rolling, in which the midrib and spadix stems split open into irregular longitudinal strips.

Main Treatment The treatment of the midrib or spadix slices is a critical step in the fibre extraction process. The main purpose of the treatment is to weaken or break the binding effect of the non- cellulosic matrix of lignin and hemicellulose.

The treatment may be achieved by several methods under varying conditions.

According to one embodiment midribs or spadix slices are treated with alkaline.

In one example the methodology is to treat the midribs/spadix slices (for example after peeling and slicing) with mild alkaline treatment, for example using a low concentration sodium hydroxide solution <5%. Here the midrib or spadix slices may be immersed into a tank containing sodium hydroxide solution with a bath (liquor) ratio which is ideally not less than 10:1.

To ensure uniform treatment, there must be continuous agitation or circulation of the sodium hydroxide solution by means of agitator or stirrer or circulation pump. Optionally a wetting agent can also be added to the bath to ensure uniform treatment. The treatment can be performed at various combinations of duration, temperature, and sodium hydroxide concentration.

The treatment results in the removal of the surface impurities and fibrillation of the vascular bundles, which may be achieved by varying for example, increasing any of the three treatment conditions: concentration, temperature, and duration. However, increasing the sodium hydroxide concentration and/or treatment temperature has been found to increase the purity of the extracted fibres and resulted in more fibrillation. Moreover, it was noticed that increasing the temperature had more pronounced effect than increasing the sodium hydroxide concentration; since, increasing the temperature tends to make the reaction more aggressive.

On the other hand, increasing the treatment duration had less pronounced effect on the removal of surface impurities, yet it had more pronounced effect on the fibrillation. Any further increase in the severity of the treatment conditions may result in over-treatment of the midrib and spadix fibres and so risk causing damage and breakage to the fibrils as shown for example in Figure 3a. Hence, in preferred examples there is optimization of the treatment conditions to extract pure undamaged midrib and spadix fibrils as shown in Figure 3b.

In one example this is achieved by treating the midrib and spadix slices at between 65 °C and 1 10 °C, preferably further between 75 °C to 100 °C, while using low sodium hydroxide concentration of 0.5% to 1 .5%, for a duration of preferably 0.8 hour to 1 .2 hour.

More preferably the concentration is between 0.9% to 1.1% for short durations (for example) 30 minutes to 2 hours and preferably for around 1 hour. However, it will be appreciated that longer processing periods may be selected, and concomitantly the concentration of sodium hydroxide may be reduced and/or the treatment temperature may be reduced accordingly in order to save energy.

Alternatively, the method can be achieved by treating the midrib and spadix slices at room temperature, with higher sodium hydroxide concentrations (5%) for longer duration (3 hours).

Thus, any of the parameters of time and/or alkali strength and/or temperature may be maintained.

Generally, the temperature of treatment in degrees Celsius is preferably in the following range: -4.82(c*d) + 92.3°C +/- 12.5°C, or preferably, -4.82(c*d) + 92.3°C +/- 6°C, where “c” is the concentration of sodium hydroxide in % (or equivalent) and “d” the duration of treatment in hours.

Other alkalis may be used, and the term “equivalent” should be understood as a solution which has the same pH as stated the sodium hydroxide (NaOH) solution.

Other alternative treatments include hydrothermal treatment which is an alternative to the treatment method that uses an alkaline substance. In one example the midribs/spadix slices (for example after peeling and slicing) are placed in hot water at temperatures from 80 °C to 100 °C in normal atmospheric pressure for a duration of 3 to 8 hours. Alternatively, the peeled and sliced midribs/spadix slices are placed in a pressurized vessel at a temperature which is between 100°C to 120°C at a pressure 0 - 1 bar for a duration between 1 to 3 hours. Another alternative treatment includes water retting which is also an alternative to the treatment method that uses an alkaline substance. In one example the methodology is to submerge the midribs/spadix slices (for example after peeling and slicing) in a water pool at an ambient temperature between 20 °C to 45 °C, in direct sun or in shade, from 1 to 16 weeks.

Scraping

After treatment of the midrib and spadix stem slices, the slices become swollen with partial dissolution of the non-cellulosic matrix. However, the matrix in this case is still surrounding the vascular fibre bundles and elemental fibrils. Hence, the scraping process is an essential step to mechanically separate the non-cellulosic matrix (delignification) without causing any damage to the fibre.

Furthermore, the scraping action causes the coarse fibre vascular bundles to split (fibrillate) into finer bundles or fibrils and eliminates the hollow content, resulting in long fine flexible textile fibres.

The scraping action can be performed using a reciprocating blunt scraper along the length of the midrib and spadix slices. It can also be performed using a rotating drum (decorticator) with multiple blunt scraping blades rotating against a stationary beater. In this case the midrib and spadix slices are fed into the clearance (<2 mm) between the rotating scraping blades and the stationary roller, in one or multiple strokes from one or both ends. It is important that the scraping is performed while the treated slices are still moist.

Washing and/or Neutralising

The fibres have to be neutralised by washing in water after extraction to reduce the pH and then soaked in a 5% solution of acetic acid after extraction to ensure that the fibre has reached a pH of around 7. Following neutralisation, the fibres are washed with water to remove any residual impurities.

Drying After washing, the fibres are dried to a moisture content of less than 20%, preferably less than 15%. The first step in the drying is either roll squeezing to remove as much water as possible or centrifugal dewatering using a mechanized drying system.

The second drying step involves hang drying the fibres in open air for several days depending on the ambient conditions or oven drying at temperature 50°C until the moisture content drops below 15%.

Brushing

After washing and drying the fibres they stick to each other by hydrogen bonding. To open the fibres, they have to be beaten or brushed. Beating and brushing is performed by a rotating drum with multiple blunt blades or short metal combs, in which the fibres are held from one end and fed into the clearance between the rotating drum and a flat metal surface in one or multiple strokes from one or both ends.

The resulting fibre at the end of the extraction method are shown in Figure 4.

Referring to Figure 6, there is shown a diagrammatical representation of the above method steps. An additional degumming step may be performed, and this is described in detail below.

Degumming

To further refine the fibres, for example to reduce any non-cellulosic impurities and to reduce the cross-sectional area of the fibre, a degumming step may be applied. The degumming is ideally performed after the brushing step and may be carried out using degumming chemicals or enzymes.

An advantage of degumming is that it helps to reduce any non-cellulosic impurities and helps to reduce the cross-sectional area of the fibre, resulting in finer and softer fibres.

In one example degumming is achieved by treating the extracted fibres at a temperature between 65 °C and 110 °C. Preferably the temperature for treatment is between 75 °C to 100 °C, while using low sodium hydroxide concentration of 1 % to 3%, and low hydrogen peroxide concentration of 0.1 % to 0.3% and 0.3% to 0.9% of sodium silicate and optionally 0.3% to 0.9% of ethylenediaminetetraacetic acid (EDTA) for a duration of preferably 2 hours to 4 hours. After chemical degumming the fibres are neutralised in 5% acetic acid solution and then washed in water.

In another example this is achieved by treating the extracted fibres between 50 °C and 65 °C, while using laccase enzyme with activity 2000 U/g and acid xylanase enzyme with activity 100,000 U/g in a buffered solution of pH 4.8, for a duration of preferably 6 hours to 10 hours. After degumming in the enzyme solution, the fibres may be scoured in a solution of 2% soda ash at 80 °C for 2 hours to remove residual gum. After scouring the fibres are neutralised in 5% acetic acid solution and then washed in water.

Technical Data

Table 1 shows average properties of long fibre extracted from date palm midrib and spadix stem using the above method. For example, the method can also be used to extract long textile fibres from the midribs of other palm species, including but not limited to Washingtonia palm (Washingtonia robusta), oil palm (Elaeis guineensis), coconut palm (Cocos nucifera), doum palm (Hyphaene thebaica), acai palm (Arecaceae) and sugar palm (Borassus f labellifer) . It may also be applied to other agriculture residues in the form of long stalks, including but not limited to bamboo.

Table 2 shows average properties of long fibre extracted from midribs of oil palm, doum palm, and Washingtonia palm.

Sodium Liqnate by-product According to another aspect of the invention there is provided a sodium lignate by-product derived using the aforementioned method of alkaline treatment of the midrib and spadix stem slices using sodium hydroxide.

The sodium lignate by-product produced according to the method may be used to make or incorporated in, a myriad different items or products, including, plasticizer for cement and concrete, as well as adhesive for wooden panels and paper.

Table 3 Chemical compositional analysis of date palm midrib sodium lignate

Peeling cellulose fluff biproduct

Cellulose fluff by-product may be formed at the midrib and spadix stem peeling stage. The cellulose fluff by-product produced according to the method may be used to make or incorporated in a myriad of different items of products, including, absorbent fluff for baby diapers and feminine hygiene pads, as well as for making pulp.

Table 4 is a chemical compositional analysis of date palm midrib cellulose fluff. There is now described a method of making gypsum plaster reinforced with date palm midrib and spadix fibres.

In an example the midrib and spadix stem slices are treated with alkaline solution of 1% sodium hydroxide at 70°C for 75 to 180 minutes. The slices are then scraped using a rotating drum (decorticator) with multiple blunt scraping blades rotating against a stationary roller with clearance from 0.4 to 0.7 mm to extract long strands of fibres. The extracted fibres are then washed and neutralised in a solution of 5% acetic acid for 1 to 30 minutes. The neutralised fibres are then washed, then dewatered using squeezing rollers and then dried to reduce the moisture content by 15%.

The dry fibres are then brushed using rotating drum with blunt metal blades. The brushed fibres are then incorporated into a wet mixture of 2-parts gypsum plaster and 1 -part water, in a weight percentage of 10% to 20% date palm midribs or spadix stem fibres and 90% gypsum plaster powder. The plaster gypsum reinforced with date palm midrib or spadix stem fibres could be cast in a shaped mold or into flat panels. The cast is then left to dry at room temperature and begins to set after 30 minutes.

The addition of date palm midrib fibres to the gypsum has enhanced its flexural performance to reach an average modulus of rupture of 1.47 MPa according to ASTM C293, which was 21 % higher than gypsum plaster reinforced with sisal fibres. Moreover, addition of date palm midrib reinforcement enhanced the compressive strength of gypsum plaster to reach 1 .87 MPa according to ASTM C109.

The gypsum plaster reinforced with date palm midrib fibres can be used in construction applications including ceiling tiles, cornices, dry walls, and facades.

There is now described a method for pulping the extracted fibre from the date palm midrib and spadix stem.

In an example the midrib and spadix stem slices are treated with alkaline solution of 5% sodium hydroxide at room temperature for 3 to 5 hours. The slices are then scraped using a rotating drum (decorticator) with multiple blunt scraping blades rotating against a stationary roller with clearance from 0.4 to 0.7 mm to extract long strands of fibres. The fibres are then chopped using a rotary cutter into lengths typically ranging from 1 to 5 cm. The chopped fibres are then pulped using a hydro-beater at a speed of 50 -400 rpm and a minimal clearance for a duration of 10 to 90 minutes to produce pulp. The pulp is then optionally bleached to whiten the pulp using 2% hydrogen peroxide at 80 °C for 30 - 120 minutes, or it can be bleached using sodium hypochlorite or other bleaching agents. The pulp may be mixed with antibacterial agent and stored for several days, or it can be formed immediately into any desired shape, including sheet form.

The pulp or sheets are then dewatered by passing through squeeze rollers and then dried until the moisture is less than 10%. The date palm midrib and spadix pulp have equivalent properties to that of bamboo pulp, which represent a new source of non-wood pulp which can be used in paper making and in moulded fibre packaging, including food packaging.

An example of an acoustic insulation panel is described in a paper by E.A. Darwish, Mohamad Midani, entitled “The potential of date palm midribs-based fabric acoustic panels for sustainable interior design” (Ain Shams Engineering Journal, Volume 14, Issue 6, 2023, 102100, ISSN 2090-4479, https://doi.Org/10.1016/j.asej.2022.102100).

Table 5 is a chemical compositional analysis of date palm midrib pulp.

A method of making thermal and acoustical insulation batts from date palm midrib and spadix fibres is now described.

In an example the midrib and spadix stem slices are treated with alkaline solution of 5% sodium hydroxide at room temperature for 3 to 5 hours. Slices are then scraped using a rotating drum (decorticator) with multiple blunt scraping blades rotating against a stationary roller with clearance from 0.4 to 0.7 mm to extract long strands of fibres. The extracted fibres are then washed and neutralised in a solution of 5% acetic acid for 1 to 30 minutes.

The neutralised fibres are then washed, then dewatered using squeezing rollers and then dried to reduce the moisture content by 15%.

The dry fibres are then brushed using rotating drum with blunt metal blades. The fibres are then chopped using a rotary cutter into lengths from 5 to 7 cm.

The chopped date palm midrib and spadix fibres are then blended with a thermoplastic binder fibre which can be polypropylene, polyester, polylactic acid, polyhydroxyalkanoates or any combination thereof.

In one embodiment the date palm midrib fibres are blended with low melt polyester in which the dry weight blend ratio is 90% date palm midrib fibre and 10% low melt polyester fibre.

Blended fibres are then air blown into a forming conveyor to form a high loft fibre batt, in which the blowing and conveyor speeds are controlled to achieve the desired batt density. The batt is then heat-set at the desired combination of thickness and density, in which the heat setting is performed using hot air-through oven at temperature from 160 to 180 °C or using heated calendars.

The batt may be impregnated with fire retardant agents including ammonium salts.

Finally, the batts are cut into desired dimensions using rotating cutting knives. The insulation batt made of date palm midrib or spadix stem fibres has low thermal conductivity and high coefficient of acoustic absorption, which is suitable for using construction, automotive and aviation sectors.

Alternatively, fibres may be mixed with other materials, such as gypsum, to enhance the strength of a composite product such as a batt or slab. In a preferred embodiment, fibres may be aligned in a specific direction or layers of alternating sheets of aligned fibres may be sandwiched together or overlaid one layer atop another to improve rigidity and/or strength of a composite building component.

Table 6 shows average properties of insulation batt from date palm midrib fibres of density 150 kg/m

An example of a thermal insulation slab is described in a paper by E.A. Darwish, Ayah Salem Eldeeb, Mohamad Midani, entitled “Housing retrofit for energy efficiency: Utilizing modular date palm midribs claddings to enhance indoor thermal comfort” (in Shams Engineering Journal, 2023, 102323, ISSN 2090-4479, https://doi.Org/10.1016/j.asej.2023.102323).

A method for making polymer composite panels reinforced with date palm midrib or spadix fibres is now described.

In an example the midrib and spadix stem slices are treated with alkaline solution of 5% sodium hydroxide at room temperature for 3 to 5 hours. The slices are then scraped using a rotating drum (decorticator) with multiple blunt scraping blades rotating against a stationary roller with clearance from 0.4 to 0.7 mm to extract long strands of fibres.

The extracted fibres are then washed and neutralised in a solution of 5% acetic acid for 1 to 30 minutes. The neutralised fibres are then washed, then dewatered using squeezing rollers and then dried to reduce the moisture content by 15%. The dry fibres are then brushed using rotating drum with blunt metal blades. The fibres are then chopped using a rotary cutter into lengths from 5 to 7 cm. The chopped date palm midrib and spadix fibres are then blended with a thermoplastic binder fibre which can be polypropylene, polyester, polylactic acid, or any combination thereof.

In one embodiment the date palm midrib fibres are blended with polypropylene in which the dry weight blend ratio is 50% date palm midrib fibre and 50% polypropylene fibre. The blended fibres are then carded to form a homogenous web, which is then cross-lapped to ensure uniform distribution of fibre orientation in the machine and cross directions.

The carded cross lapped non-woven web is then felted using needle punching method, in which barbed needles ae punched through the web to consolidate the web by entangling the fibres resulting in a web with areal density from 1 ,200 - 2,000 gram per square metre.

In one embodiment the felted nonwoven is hot compression molded at 183 °C for 15 minutes at 15 MPa, and then cooled before demolding.

In another embodiment the felted nonwoven is thermoformed in which the nonwoven is heated in a convection or conduction oven at 160 °C to 180 °C for 10 to 20 minutes and then pressed using a cold mold for 5 minutes at 15 MPa and then demolded.

The date palm midrib fibre reinforced composite is a light weight, recyclable, and partly biodegradable composites that can be used in nonstructural applications in the automotive door panels, trunk liners, parcel shelves, trimmings and other interior parts.

An example of a composite panel is described in a paper by Elseify, L.A., Midani, M., El- Badawy, A.A. et al. entitled “Benchmarking automotive nonwoven composites from date palm midrib and spadix fibers in comparison to commercial leaf fibers”. (Biomass Conv. Bioref. (2023). https://doi.org/10.1007/s13399-023-03910-w). Composite (50PP%/ 50 palm Date Palm Date Palm Standard fibre%) Midrib Spadix Test

Areal Density (gm/m²) 1 ,694 1 ,597 ASTM D3776

Thickness (mm) 2.0 1.9

Tensile Strength (MPa) 21.1 22.4 ASTM D3039

Tensile Young’s Modulus (GPa) 2.8 2.5 ASTM D3039

Flexural Strength (MPa) 34.7 33.0 ATSM D790

Flexural Chord Modulus (GPa) 2.4 2.2 ATSM D790

Drop weight Impact Peak Load (N) 399.6 426.2 ASTM D3763

Drop weight Impact Total Energy 2.2 2.5 ASTM D3763

(J)

Table 7 shows average properties of PP composite reinforced with date palm midrib and spadix stem fibres.

It will be appreciated that variation may be made to the aforementioned embodiments, without departing from the scope of protection as defined by the claims.

Claims

1 . A method of obtaining fibres from species of palm trees, the method including the step (a) of treating stems to delignify them by application of an alkali solution and (b) scraping the treated stems to mechanically remove the non-cellulosic matrix and fibril late the fibre vascular bundles by application of a scraper.

2. A method of obtaining fibres claimed in claim 1 including the step (w) of treating stems to delignify them by water retting, at a temperature from 20 °C to 45 °C in water.

3. A method as claimed in either claim 1 or 2 wherein the alkali solution is a sodium hydroxide solution.

4. A method as claimed in any of claims 1 to 3 wherein step (a) comprises soaking stems in an alkali solution at a temperature t where t is in the range of: t = -4.82(c*d) + 92.3 °C +/- 12.5°C, where c is the concentration of sodium hydroxide in %, or pH equivalent, and d the duration of treatment in hours.

5. A method as claimed in claim 4 wherein step (a) comprises soaking the stem in an alkali solution at a temperature t, where t is in the range of: t = -4.82(c*t) + 92.3 °C +/- 6°C.

6. A method as claimed in any of claims 2 to 5 wherein step (w) comprises soaking stems in water at temperature between 95 °C and 100 °C in normal atmospheric pressure or in a pressurized vessel at temperature 100 °C to 120 °C at a pressure 0 - 1 bar for a duration 1 to 3 hours.

7. A method as claimed in any of claims 2 to 5 wherein step (w) comprises soaking stems in a water pool at ambient temperature 20 °C to 45 °C, in direct sun or in shade, from 1 to 16 weeks.

8. A method as claimed in any preceding claim includes an initial step (c) of separating the leaflets from palm fronds.

9. A method as claimed in any preceding claim includes a prior step (d) of peeling the outer layer of the palm stems.

10. A method as claimed in any preceding claim includes a prior step (e) of slicing the stems longitudinally to reduce their thickness.

11. A method as claimed in any preceding claim includes a subsequent step of (f) which washes and/or neutralizes the product obtained using step (b).

12. A method as claimed in any preceding claim including a subsequent step of (g) which is drying the product obtained from step (f).

13. A method as claimed in any previous claim including a step (h) of brushing the fibres/product obtained from step (g).

14. A method as claimed in claim 13 including a step (i) of degumming the fibres/product obtained from step (g) by treating fibres between 65 °C and 110 °C, with a low sodium hydroxide concentration of 1% to 3%, and low hydrogen peroxide concentration of 0.1 % to 0.3% and 0.3% to 0.9% of sodium silicate.

15. A method as claimed in claim 14 wherein step (i) of further includes treating the fibres with a 0.3% to 0.9% of ethylenediaminetetraacetic acid (EDTA) for a duration of preferably 2 hours to 4 hours.

16. A method as claimed in any preceding claim including a step (i) of degumming the fibres/product obtained from step (g) by treating the extracted fibres between 50 °C and 65 °C, while using laccase enzyme with activity 2000 U/g and acid xylanase enzyme with activity 100,000 U/g in a buffered solution of pH 4.8, for a duration of between 6 hours to 10 hours.

17. A method of obtaining fibres from species of palm trees, the method includes the steps of soaking fibre stems in a water pool at an ambient temperature 20 °C to 45 °C.

18. A method as claimed in claim 17 wherein soaking is performed in direct sun or in shade.

19. A method as claimed in claim 17 or 18 wherein soaking is performed for a period of between 1 and 16 weeks.

20. A method of obtaining fibres from species of palm trees, the method comprises the steps of placing midribs/spadix slices in hot water at temperature from 80 °C to 100 °C in normal atmospheric pressure for a duration of between 3 to 8 hours.

21. A method as claimed in claim 20 wherein midribs/spadix slices are placed in a pressurized vessel at a temperature which is between 100°C to 120°C at a pressure 0 - 1 bar for a duration between 1 to 3 hours.

22. A method as claimed in claim 20 or 21 wherein the midribs/spadix slices are peeled prior to slicing.

23. A fibrous product derived using the method according to any preceding claim.

24. Cellulose fluff derived from the fibrous product according to claim 23.

25. An absorbent material in baby diapers and feminine hygiene pads, as well as for making pulp.

26. A baby diaper includes the absorbent material according to claim 26.

27. A feminine hygiene pad including the absorbent material according to claim 26.

28. An item of clothing or footwear including the fibrous product according to claim 23.

29. A sheet of flexible material including the fibrous product according to claim 23.

30. An item for use in automotive or construction, such as boards or insulation panel, includes the fibrous product according to claim 23.

31 . Rope including the fibrous product according to claim 23.

32. Sodium lignate derived using the method according to any of claims 1 to 19.

33. A plasticizer for cement and concrete, filler or an adhesive including sodium lignate according to claim 32.

34. A batt includes a mixture of gypsum and the fibrous product according to claim 23.