CZ307683B6 - A composite material comprising fibrous reinforcement in combination with nanofibers and a method for its production - Google Patents

Description

Structural composite material including fiber reinforcement in combination with nanofibers and method of its production

Field of technology

The invention relates to a structural composite material formed by fiber reinforcement with nanofibers and a method of its production including impregnation using an impregnation material in combination with plasma treatment.

Current state of the art

Structural composite materials including fiber reinforcement and impregnation material are used in the aerospace, military, marine, sports, automotive, electrical engineering, medical industries and many other applications where strength, flexibility, chemical and corrosion resistance, electrical and thermal conductivity/non-conductivity or low weight, or on other specific properties of structural composite materials.

The currently known state of processing of composite nanomaterials and fiber reinforcements, which is the closest to the presented solution, is described in the following paragraphs.

European patent EP 2504471 B1 describes a linear fiber containing nanofibers placed on a linear fiber core. The nanofibers are fixed to the linear fiber core by means of at least one cover thread that wraps the fibers. Furthermore, a method of manufacturing a linear fiber formation containing a linear fiber core is described here, on which nanofibers produced by electrostatic spinning of a polymer matrix are deposited in the spinning space of a high-intensity electric field. The invention also relates to a device for the production of a linear fiber structure containing a linear fiber core on which nanofibers produced by electrostatic spinning of a polymer matrix are placed in the spinning space of the electric field created between the spinning electrode and the collecting electrode.

The disadvantage of the production method according to patent EP 2504471 Bl can be seen in the complexity of the production process. Nanofibers are applied to a linear fiber core-filament that rotates around its axis. There are from 1,000 to 64,000 of these fiber core filaments in one strand (roving). Each filament needs to be wrapped with nanofibers to create a covering layer. A strand (roving) is formed from individual filaments arranged in a bundle in the number of 1,000 to 64,000 pcs. These rovings are further used for the production of fiber reinforcements in woven or non-woven weaves. For example, there are 177 rovings in a 600 mm wide unidirectional weave, where each roving contains 12,000 filaments, i.e. a total of 2,124,000 filaments, which, according to this patent, would have to be wrapped with a covering layer of nanofibers. Another disadvantage is the handling of filaments with dimensions of around 6 pm, which results in their mechanical stress, and thus the degradation of their properties in the area of strength and flexibility of the finished composite material. In the case of a wrap of a fiber core in the form of a roving, i.e. a wrap of 1,000 to 64,000 filaments together, a problem arises with the high-quality impregnation of the individual filaments with a binder/matrix, and this leads to their non-connection with each other using the matrix, the formation of air pockets and a significant reduction in the mechanical properties of the composite product.

Czech utility model CZ 27368 U1 describes a textile composite for outdoor applications, especially clothing and equipment, which contains a supporting textile layer and a layer of polymer nanofibers placed on top of it, which is firmly connected to it, and the connection of these two layers is realized in such a way that on the surface of the layer of polymer nanofibers facing away from the supporting textile layer, a network/grid of formations of at least one polymer is printed. The layer of polymeric nanofibers is equipped with a system of point formations made of polymer, between which the layer of polymeric nanofibers is freely accessible, the point formations prevent the mutual movement of the nanofibers.

- 1 CZ 307683 B6

The disadvantage of this solution, however, is that the solid connection of the supporting textile layer with the layer of polymeric nanofibers in the area with a suitable binder worsens the permeability and vapor permeability of the textile nanocomposite and, above all, simply applying point formations from the polymer to the layer of polymeric nanofibers does not fix the individual nanofibers and the layers created from them, because the point the formations are applied (printed) only on the surface of the layer of polymer nanofibers and do not penetrate this layer spatially, i.e. in cross-section.

Patent application CZ 20100373 A3 describes a nanofibrous composite with increased strength and abrasion resistance, which is connected through the entire thickness by a reinforcing (impregnation) material and the method of manufacturing this composite. The reinforcing material can also be used for connection with another layer or substrate. The document lists the possible materials of the carrier layer (substrate) - mainly flat textile, also paper, filter paper, metal or plastic foil or grid, etc. It is mainly an application for textile purposes. In addition, the described method of production has several disadvantages: a) it is not possible to use more different fabrics or nonwovens and it is necessary to use mainly those that are suitable for spinning nanofibers, and a large number of substrates are not suitable, which limits the width of the use of textiles; and b) during the transfer of nanofibers from an endless belt to a fabric intended for lamination with nanofibers, according to the described procedure, it is impossible to transfer such a thin material without breaking it, at least the pores in the membrane/layer will expand, which leads to mechanical failure and destruction of properties.

Czech patent CZ 305039 B6 describes the wrapping of individual fibers/filaments of nanofibers. The disadvantage of this solution is precisely the wrapping of individual filaments, e.g. carbon fiber. Fibrous reinforcements for composite materials consist of filaments that are arranged in bundles (rovings) and the reinforcement is woven from the roving. One filament has a diameter of 6 micrometers, a roving consists of 1,000 to 12,000 filaments, and there are approximately 200 to 2,000 rovings in lm ² . The total number of filaments in lm ² is therefore around 2 million. This would require spinning and wrapping such a number of filaments, which would be very expensive and time-consuming. In the case of non-woven fabric/fiber reinforcement, this document is absolutely useless. Another disadvantage is the handling of such thin fibers, which are very susceptible to any manipulation, due to which they lose their very important mechanical properties.

In the Czech utility model CZ 27818Ulje, a textile nanocomposite is described, which consists of a supporting textile layer to which a layer of polymeric nanofibers is attached. The textile layer and the layer of polymer nanofibers are connected together by scattered fragments of at least one polymer in the area of both layers. These fragments touch the textile layer and penetrate the polymer nanofiber layer. The nanocomposite mainly consists of several individual layers. The disadvantage is that when applying an amount of binder/matrix to the fiber reinforcement, which varies in the size of units of grams per 1 m ² and then applying individual lamination points, a continuous layer of binder is not formed. Due to such a procedure, the fiber reinforcement will not be sufficiently saturated, which has the effect of not fixing the fibers in the composite, while the fixing of the fibers in the composite is necessary for the strength and flexibility of the composite.

The textile nanocomposite described in utility model CZ 27818 U1 is used for textile purposes, primarily for nanofibrous membranes that are waterproof but also vapor permeable. It is the vapor permeability of these materials that is essential and can be corrected by the amount and location of the lamination points of the binder/matrix. It is the continuous layer of binder/matrix that would seal/clog the individual pores of the nanofibrous membrane and thus absolutely and irreversibly destroy the advantage in the combination of water resistance and vapor permeability, which are necessary for vapor permeable textiles.

In the Chinese invention application CN 102720061 A, a method of preparing carbon fibers for improving the surface properties of a composite material is described. Carbon fibers are activated by free radicals created on their surface using a plasma in a mixture of argon and oxygen gases under the action of the maleic anhydride agent. The polymerization rate of the reaction of free radicals and maleic anhydride is accelerated when the temperature also increases, and the reaction rate for the activation of carbon fibers is only 3 minutes to 7 minutes. For improvement

-2CZ 307683 B6 of the desired properties, activated carbon fibers are subjected to the action of epoxy resin.

European patent EP0110118B1 EPO 110118 B1 describes an invention that relates to a method of improving the surface properties of carbon fibers, in which the surface of the carbon fibers is subjected to exposure to a plasma atmosphere of an inorganic gas or a gas mixture under reduced pressure - at least below 1330 Pa inside the plasma chamber, whereby the gas or the gaseous mixture consists of oxygen. Plasma is generated by a glow discharge using an electrical voltage. Carbon fibers treated in this way are provided with materials such as synthetic resins on their surface to improve their adhesion properties with other materials.

For the production of composite products consisting of fiber reinforcements, polymer nanofibers and an impregnation agent, several basic procedures and production equipment are used according to the current state of the art, or combinations thereof, which are summarized in the following points:

• Furnace combined with or without vacuum bag • Pressure chamber (autoclave) combined with or without vacuum • Pressing technique • Mold with pressure bag • Pipe winding process

The best properties of the composite product in terms of strength and flexibility are achieved in a combination of autoclave and vacuum. The matrix/binder-impregnated reinforcement is placed together with the mold into a vacuum bag, from where air is sucked to a pressure of -100 to -990 mbar. This bag, in which there is a vacuum, is put into an autoclave, which is closed, together with the mold and the impregnated fiber reinforcement. Using a compressor, air is blown into the autoclave chamber until a pressure of 400 to 1500 kPa is reached. Impregnation materials, which are most often used to achieve the best possible properties of the composite product, are cured at temperatures of 25 to 200 °C. The autoclave chamber is heated to a value of 80 to 200 °C when heat-activated impregnation material is used. After reaching the required pressure in the autoclave chamber, the curing process is started.

The disadvantage of this processing is the energy requirement, which means the energy consumption of the compressor, the time requirement (for example, when pressurizing the working chamber to 400 to 1500kPa) and also the investment costs of acquiring such a chamber together with a powerful compressor. The complexity of the entire process in the production of composite materials is high. These disadvantages can be eliminated by different methods of manufacturing a fiber composite product, such as for example a combination of production procedures in which a furnace with a vacuum bag, a pressing technique or a mold with a pressure bag is used. Unfortunately, in addition to their advantages, all these procedures also have disadvantages in terms of the quality of the composite products, primarily in the deterioration of its strength limit and effective modulus of elasticity compared to the autoclave method in combination with vacuum.

The invention aims to create a composite material in combination with nanofibers that achieves higher values of ultimate strength, effective modulus of elasticity and, in particular, increases the efficiency of the production of the final product from the composite material, which is achieved using nanofibers applied to fiber reinforcement and their activation using plasma treatment and impregnation with impregnation material.

The essence of the invention

The above-mentioned disadvantages are eliminated by a structural composite material consisting of a fiber reinforcement and a layer of nanofibers, the essence of which is that the fiber reinforcement weighing from 20 to 1200 g/m ² is formed by external fibers and internal fibers, while the external fibers are penetrated by nanofibers with a diameter 10 to 250 nm and a weight of 0.2 to 72 g/m ² , while the fiber reinforcement and the layer of nanofibers are permeated throughout the entire volume with impregnation

-3 CZ 307683 B6 material, while the impregnation material in the amount of 6 to 3000 g/m ² permeates the outer fibers and inner fibers of the fiber reinforcement and the layer of polymeric nanofibers.

The fiber reinforcement layer can be made of the following materials:

- Fiberglass

- Carbon fibers

- Aramid fibers

- Polyethylene fibers (PET)

- Polyamide fibers (PA)

- PBO fibers [(poly(p-phenylene-benzobisoxazole)]

- PIPD fibers poly{2,6-diimidazo[4,5-b:4',5'-E]pyridinylene-1,4-(2,5-dihydroxy)phenylene}

- Whisker thread

- Basalt/basalt fiber

- Para-aramid fibers or their combinations or known derivatives.

The above-mentioned fiber reinforcements are created as outer fibers and inner fibers arranged in canvas, satin, twill, one-way, basket, pearl, multi-axial weave or in non-woven weave and are subsequently impregnated with an impregnation material in the amount of 6 to 3000 g/m ² . whereas the fiber reinforcement has a weight from 20 to 1200 g/m ² .

In order to achieve the best possible adhesion properties of the fibers of the fiber reinforcements to each other, it is advantageous if the impregnation material consists of a material consisting of epoxies, polyesters, acrylates, or their mutual combination.

The production of the composite material described above is a continuous process, when the fibers are saturated with the impregnation material, the structural composite material is wound onto the sleeve. To easily separate the layers of impregnated fiber reinforcement and prevent contact between them during winding, it is advantageous to apply a separation film made of polyethylene, silicone paper and/or paper covered with a polyethylene layer to the resulting structural composite material on both sides.

The method of manufacturing a structural composite material consisting of fiber reinforcement in combination with nanofibers consists in the fact that, in the first step, a layer of nanofibers with a diameter of 10 to 250 nm and a weight of 0.2 to 72 g/m ² is applied to the surface of the outer fibers in at least one layer and then, in the second step, the fiber reinforcement and the layer of nanofibers are impregnated in the entire volume with an impregnation material in the amount of 6 to 3000 g/m ² .

In order to improve the adhesion properties of nanofibers and fiber reinforcements with the matrix, thereby achieving a higher tensile strength and effective modulus of elasticity, the fibers of the fiber reinforcement and layers of nanofibers are activated and modified using a plasma of low temperature and pressure in an ionized gaseous environment before impregnation with the impregnation material/matrix /em Co, O2, Ar, N2, CO2, NH3, Ne, He or monomers based on silanes, siloxanes and/or acrylates or a combination thereof. Thanks to the activation of the fibers by plasma treatment, the surface tension will be reduced and the fiber surface of the fiber reinforcement will be more thoroughly wetted in combination with nanofibers and with or without impregnation material, while in the hardened state the load and stress of the finished composite product will be transferred to the fibers.

The advantage of using a composite material including nanofibers is that no special manufacturing equipment is needed to produce the final composite product.

Thanks to the nanofibers contained in the fiber reinforcements, we can achieve an increase in the strength limit and the effective modulus of elasticity of the resulting composite material during its production even with the minimal use of increased pressure in the autoclave and vacuum, thus during industrial production

-4CZ 307683 B6 of the final composite product, the consumption of electricity will be reduced due to the lower consumption of the compressor and the vacuum pump, the productivity will also increase due to the pumping of lower pressure into the autoclave chamber and the investment costs will be reduced due to the lower demands on the performance of the compressor and the sealing of the autoclave, or the equipment will not be needed at all purchase an autoclave for the production of a composite product.

By using nanofibers in combination with fiber reinforcement in composite materials, at least comparable and in many cases better properties are obtained in terms of strength and flexibility of the final structural composite product, using all presented composite product manufacturing procedures. For example, with the autoclave and vacuum method, there is no need to pressurize the chamber to a pressure of 400 to 1500 kPa, but a pressure of 10 to 100 kPa or atmospheric pressure is fully sufficient to achieve comparable properties in the area of ultimate strength, effective modulus of elasticity of composite materials, and thus a significant increase in production efficiency.

The advantages of the invention are summarized in the following points:

• Increasing the ultimate strength of the hardened structural composite product.

• Increasing the effective modulus of elasticity of the cured structural composite product.

• Increasing the productivity of construction composite product production.

• Lower investment costs for the production of products from structural composite materials.

• Lower energy requirements for the production of products from structural composite material.

• Lower operating costs for the production of products from structural, composite materials

Clarification of drawings

The invention will be explained in more detail with the help of figures, in which Fig. 1 shows a fiber reinforcement in combination with polymer nanofibers consisting of a fiber reinforcement provided with a layer of polymer nanofibers, Fig. 2 shows a fiber reinforcement in combination with polymer nanofibers, while this fiber reinforcement is provided on both sides with a layer of polymeric nanofibers and a layer of impregnation material penetrating the layer of fiber reinforcement and the layer of polymeric nanofibers and wrapped with a separation film and separation paper, Fig. 3 to Fig. 11 show examples of fiber reinforcement bonds, Fig. 12 shows the increase in tensile strength of the nanocomposite, Fig. 13 shows increase in the effective modulus of elasticity of the nanocomposite, Fig. 14 shows a more thorough saturation of the individual fibers of the composite and its effect on strength after plasma treatment, Fig. 15 shows a more thorough saturation of the individual fibers of the composite and its effect on the increase of the effective modulus of elasticity of the composite after plasma treatment, and Fig. 16 shows the difference in pressurization time, thereby increasing production productivity at atmospheric pressure and pressure increased by 1 bar.

Examples of implementation of the invention

An example of a structural composite material is shown in Fig. 1. The structural composite material in this embodiment consists of a fiber reinforcement 2 comprising outer fibers 22 and inner fibers 21 in combination with a layer 1 of nanofibers 11, wherein the inner fibers 21 and outer fibers 22 form the known canvas, satin . . - aramid fibers or their combination. The structural composite material provided on one side with a separation film 4 and on the other side with a paper 5 with a polyethylene layer can be created as follows:

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The first example of the design of the structural composite material includes a layer 1 of polymer nanofibers 11 formed by a PA polymer, where the diameter of the nanofibers 11 is 130 ± 120 nm with a weight of 4.8 g/m ² , while these nanofibers 11 penetrate the outer fibers 22 of the fiber reinforcement 2, which is formed carbon fibers with a weight of 160 g/m ² arranged in a direct bond. The impregnation material 3 in the amount of 115 g/m ² penetrates through the outer fibers 22 and inner fibers 21 of the fiber reinforcement 2 and the layer 1 of polymer nanofibers 11 throughout their volume.

The second embodiment of the structural composite material includes a layer 1 of nanofibers 11 formed by a PES polymer, where the diameter of the nanofibers 11 is 130 ± 120 nm with a weight of 13 g/m ² , while these nanofibers 11 adhere to the outer fibers 22 of the fiber reinforcement 2, which is made of glass fibers with a weight of 220 g/m ² arranged in a canvas binding. The impregnation material 3 in the amount of 132 g/m ² permeates the outer fibers 22 and the inner fibers 21 of the fiber reinforcement 2 and the layer 1 of polymeric nanofibers 11.

The third example of the design of the structural composite material includes a layer 1 of polymer nanofibers 11 formed by a PA polymer, where the diameter of the nanofibers 11 is 130 ± 120 nm with a weight of 2.8 g/m ² , while these nanofibers 11 penetrate the outer fibers 22 of the fiber reinforcement 2, which is formed carbon fibers weighing 160 g/m ² arranged in a twill weave. The impregnation material 3 in an amount of 224 g/m ² permeates the outer fibers 22 and the inner fibers 21 of the fiber reinforcement 2 and the layer 1 of polymeric nanofibers 11. A comparison of the strength limit and the effective modulus of elasticity of the structural composite material according to this exemplary embodiment with the designation (N_K_1 -4) and the fiber reinforcement 2 consisting of carbon fibers weighing 160 g/m ² without nanofibers and epoxy resin with the designation (SK I-4) is evident from Tab. 1.

Sample ťT max [MPa] E [GPa] Sample ¢7 max [MPa] E [GPa] N_K_1 443.5 33.4 S_K_1 352.3 32.0 N_K_2 427.4 33.1 S_K_3 349.7 31.3 N_K_3 385.4 32.8 S_K_4 289.0 32.5 N_K_4 417.8 32.6 S_K_5 328.3 31.8

The average value of the effective modulus of elasticity for the S K samples is E = 31.9 GPa. The average value of the ultimate tensile strength for the S_K samples is σ max = 329.83 MPa. The average value of the effective modulus of elasticity for the N_K samples is E = 32.88 GPa. The average value of the tensile strength limit for N_K samples is σ^χ = 418.52 MPa. The tensile strength of the N_K sample is higher by 26.88% and the effective modulus of elasticity by 3.37% due to the added nanofibers.

Polyamide nanofibers were produced for plate samples marked N_K in an amount of 4.8 g/m ² using electrospinning on a 160 g/m ² carbon fiber base in a twill weave. Subsequently, the carbon and nanofiber reinforcement was manually saturated with epoxy resin and cured at a temperature of 20 °C and a pressure of 0.1 bar.

Another exemplary embodiment of the structural composite material is shown in Fig. 2. The structural composite material in this embodiment consists of fiber reinforcement 2, which includes outer fibers 22 and inner fibers 21, and which is provided on both sides with a layer 1 of polymer nanofibers 11 and impregnation material/impregnation matrix 3 penetrating layer 1 of polymer nanofibers 11 and fiber reinforcement 2. The impregnation material/impregnation matrix 3 can be epoxies,

-6CZ 307683 B6 polyesters, acrylics or mutual combinations of the listed materials. The inner fibers 21 and the outer fibers 22 may be fixed in a known plain, satin, twill, one-way, basket, pearl, multi-axial weave or may be fixed in a non-woven weave as shown in Fig. 3 to Fig. 11. Layer 1 of polymer nanofibers 11 in the structural composite material can be formed by nanofibers 11 selected from the group of polymers PA, PAN, PUR, PES, PVDF or their mutual combination. The inner fibers 21 and the outer fibers 22 of the fiber reinforcement 2 can be made of glass fibers, carbon fibers, aramid fibers, polyethylene fibers, polyamide fibers, PBO fibers, PIPD fibers, whisker fibers, basalt or basalt fibers, para-aramid fibers, or a combination thereof.

The fourth example of the design of the structural composite material includes a layer 1 of polymer nanofibers 11, which is made of a PAN polymer, where the diameter of the nanofibers 11 is 130 ± 120 nm with a weight of 15 g/m ² , while these nanofibers 11 penetrate the outer fibers 22 of the fiber reinforcement 2, which is formed by basalt fibers weighing 300 g/m ² arranged in an atlas weave. The impregnation material 3 permeates the fiber reinforcement 2 and the layer 1 of polymeric nanofibers 11 in an amount of 210 g/m ² . The structural composite material created in this way is provided on one side with a separation polyethylene film 4 and on the expensive side with polyethylene paper 5.

The fifth embodiment of the structural composite material includes a layer 1 of polymer nanofibers 11, which is made of PVDF polymer, where the diameter of the nanofibers 11 is 130 ± 120 nm and the weight of the layer 1 is 8.4 g/m ² , while these nanofibers 11 penetrate the outer fibers 22 reinforcement 2 weighing 300 g/m ² , which consists of aramid fibers arranged in a basket weave. The impregnation material 3 permeates the fiber reinforcement 2 and the layer 1 of polymeric nanofibers 11 in an amount of 180 g/m ² . The structural composite material created in this way is provided on one side with a polyethylene separation film 4 and on the expensive side with silicone paper 5.

The sixth embodiment of the structural composite material includes a layer 1 of polymer nanofibers 11, which is formed by a combination of PAN and PVDF polymers in a ratio of 50:50, where the diameter of the nanofibers 11 is 130 ± 120 nm and the weight of the layer J_ is 4.5 g/m ² , while the layer 1 of polymer nanofibers 11 permeates the outer fibers 22 of the fiber reinforcement 2 weighing 300 g/m ² , which is formed by glass fibers arranged in a basket weave. The impregnation material 3 permeates the fiber reinforcement 2 and the layer 1 of polymeric nanofibers 11 in an amount of 330 g/m ² . The structural composite material created in this way is provided with a separation film 4 on one side and silicone paper 5 on the expensive side.

Comparison of the results of measuring the ultimate strength and effective modulus of elasticity of structural composite material 1 made of straight carbon fibers (UD fibers) weighing 300 g/m ² with the designation (l_0-95_B, 3_0-95_B, 5_0-95_B, 5_0-l_B) and structural composite material consisting of straight carbon fibers (UD fibers) weighing 300g/m ² in combination with PA nanofibers in the amount of 10.8 g/m ² with the designation (l_0-95_S, 3_0-95_S, 5_0-l_S) and with a content of 174 g/m ² matrix (epoxy resin) is shown in Tab. 2.

Tab. 2: Measurement of ultimate strength and effective modulus of elasticity

Samples σ _Μ χ [MPa] E[GPa] l_0-95_B 1947.87 110.32 3_0-95_B 1830.59 106.54 5_0-95_B 2116.35 111.94 5_0-1_B 2186.87 111.11 l_0-95_S 2201.31 114.81 3_0-95_S 2009.04 109.37 5_0-1_S 2176.27 112.51

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From Tab. 2, it is clear that the samples of structural composite material with nanofibers l_0-95_S (pressure: 1 bar, vacuum: 0.95, S: with polymer nanofibers) have better properties both in terms of tensile strength and effective modulus of elasticity than samples from conventional material without polymer nanofibers, even in the case of samples 5_0-95_B, 5_0-1_B (pressure: 5 bar, vacuum: 0.95 0.1, B: without nanofibers). For samples marked 10-95, an increase in the average value of the maximum stress by 13% was found when using nanofibers, for samples 3 0-95 there was an increase of 10%.

In the combination of the manufacturing method of the structural composite material according to claim 8 and 9, it is advisable to first activate the fiber reinforcement 2 and the layer 1 of polymeric nanofibers 11 before saturating the structural composite material formed by fiber reinforcement 2, on which layer 1 of polymeric nanofibers 11 is applied, and impregnation material 3 by plasma at a low temperature and pressure in an ionized gas environment with gases/em Co, O2, Ar, N2, CO2, NH3, Ne, He or monomers based on silanes, siloxanes or acrylates or their combinations.

The measurement of the tensile strength MPa and the effective modulus of elasticity GPa of a carbon fiber composite weighing 160 g/m ² in a plasma-treated twill weave marked K_P and containing 112 g/m ² impregnation material 3 (epoxy resin) is shown in Tab. 3.

Sample σ max [MPa] E [GPa] K_P_1 366.1 35.3 K_P_2 342.8 34.3 K_P_3 379 35.1 K_P_4 391.3 32.9 K_P_5 322.8 32.9 K_P_6 368.9 34.7

The average value of the effective modulus of elasticity for the samples of structural composite material marked K_P is E = 34.18 GPa. The average value of the tensile strength limit for samples of structural composite material marked K_P with an allowable failure mode is σmax = 361.82 MPa. The measurement of the tensile strength MPa and the effective modulus of elasticity GPa of a carbon fiber composite weighing 160 g/m ² in a twill weave without plasma treatment marked SKa with a content of 112 g/m ² impregnation material 3 consisting of epoxy resin is shown in Tab. 4.

Sample C max [MPa] E [GPa] S_K_1 352.3 32.0 S_K_2 328.3 31.8 S_K_3 349.7 31.3 S_K_4 289.0 32.5 S_K_5 375.9 32.6 S_K_6 383.5 32.3

The average value of the effective modulus of elasticity for the samples of structural composite material marked S K is E = 32.09 GPa. The average value of the tensile strength limit for samples of structural composite material marked S K with an allowable failure mode is CTmax = 346.45 MPa.

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The results show that the tensile strength of the modified carbon fiber is 4.4% higher and that the effective modulus of elasticity is increased by 6.5%.

During the production of the sample according to Fig. 12, a fiber reinforcement made of straight HS (high strength) fibers - with a high strength of 300 g/m ² (with a matrix content of 58% of the weight of the fiber reinforcement) made of carbon fibers was transferred by means of nanofiber lamination to the already saturated fiber reinforcement. . The nanofibrous composite was enclosed in a polyethylene bag, and air was drawn off with a vacuum to create a vacuum. It was then placed in an autoclave and, according to the specifications of the samples listed in Table 2, a pressure of 1, 3, 5 bar was reached. After pressurizing the chamber, the curing process was started at a temperature of 125 °C for 1 hour.

During the production of the sample in Fig. 13, the already saturated fiber reinforcement made of straight fibers HS (high strength) - with a high strength of 300 g/m ² (with a matrix content of 58% of the weight of the fiber reinforcement) from carbon fibers was transferred by lamination of nanofibers. The nanofibrous composite was enclosed in a polyethylene bag, and air was drawn off with a vacuum to create a vacuum. It was then placed in an autoclave and according to the specifications of the samples listed in Table 2, the autoclave chamber was pressurized to a pressure of 1, 3, 5 bars. After pressurizing the chamber, the curing process was started at a temperature of 125 °C for 1 hour.

During the production of the sample from Fig. 14, the carbon fiber reinforcement in AS (average strength) canvas weave - with an average strength of 160 g/m ² was placed in a low-pressure and low-temperature plasma chamber, where it was in a combination of O2, Ar, N2, He gases process of surface treatment of fiber reinforcement with ionized gas started in vacuum. After removing the fiber reinforcement from the chamber, it was saturated with epoxy resin in the laminating device and cured at a temperature of 20 °C and a pressure of 0.1 bar.

During the production of the sample from Fig. 15, the carbon fiber reinforcement in AS (average strength) canvas weave - with an average strength of 160 g/m ² was placed in a low-pressure and low-temperature plasma chamber, where it was in a combination of O2, Ar, N2, He gases process of surface treatment of fiber reinforcement with ionized gas started in vacuum. After removing the fiber reinforcement from the chamber, it was saturated with epoxy resin in the laminating device and cured at a temperature of 20 °C and a pressure of 0.1 bar.

Fig. 16 shows the time and operational savings, when in the case of nanocomposite there is no need to pump a pressure of 5 to 10 bar, but a pressure of 0.1 or 1 bar or atmospheric pressure is fully sufficient to achieve better or similar mechanical properties, as in the case of using a conventional structural composite material at a pressure of 5 and more bars.

Industrial applicability

The invention finds industrial applicability in the production of final products from structural composite materials in structures in the aviation, military, ship, sports, automotive, electrotechnical, medical industries, as well as ballistic protection and in many other applications, where the focus is on strength and flexibility at the same time. chemical and corrosion resistance, electrical and thermal non-conductivity or conductivity, low weight or other specific product properties.

Claims (1)

Structural composite material consisting of a fiber reinforcement (2) and a layer (1) of nanofibers (11), characterized in that the fiber reinforcement (2) weighing from 20 to 1200 g/m ² is formed by outer fibers (22) and inner fibers (21), while the outer fibers (22) of the fiber reinforcement (2) adjoins -9CZ 307683 B6 layer (1) of nanofibers (11) with a diameter from 10 to 250 nm and a weight of 0.2 g/m ² to 72 g/m ² and also fiber reinforcement (2) and layer (1) of nanofibers (11) are permeated throughout the entire volume with the impregnation material (3), while the impregnation material (3) permeates the outer fibers (22) and inner fibers (21) of the fiber reinforcement (2) and the layer (1) of polymer nanofibers (11) in an amount of 6 g/m ² to 3000 g/m ² . Structural composite material according to claim 1, characterized in that the outer fibers (22) and inner fibers (21) of the fiber reinforcement (2) are made of glass fibers, carbon fibers, aramid fibers, polyethylene fibers, polyamide fibers, PBO fibers, PIPD fibers , whisker fibers, basalt or basalt fibers, para-aramid fibers or a combination thereof. Structural composite material according to claim 1 or 2, characterized in that the outer fibers (22) and inner fibers (21) are in a straight, plain, satin, twill, one-way, basket, pearl, multi-axial weave or in a non-woven weave. Structural composite material according to claims 1, 2 or 3, characterized in that the nanofibers (11) are made of a material selected from the group of polymers PA, PAN, PUR, PES, PVDF or their mutual combination. Structural composite material according to claim 1, characterized in that the impregnation material (3) is formed by a material consisting of epoxies, polyesters, acrylates, or their mutual combination. Structural composite material according to claims 1, 2, 3, 4 or 5, characterized in that the composite material (1') is provided on one side with a separation film (4) and on the other side with a separation paper (5). Structural composite material according to claim 6, characterized in that the separation film (4) is made of polyethylene film and the separation paper (5) is made of silicone or polyethylene paper. The method of manufacturing a structural composite material consisting of fiber reinforcement (2) in combination with nanofibers (11) according to the previous claims, characterized in that at least one layer (1) of nanofibers (11) with a diameter of 10 to 250 nm and a weight of 0 is first applied. 2 to 72 g/m ² on the surface of the outer fibers (22) of the fiber reinforcement (2) and then the fiber reinforcement (2) and the layer (1) of the nanofibers (11) are impregnated in the entire volume with the impregnation material (3) in an amount of 6 to 3000 g/m ² . The method of manufacturing a structural composite material according to claim 8, characterized in that before the nanofibers (11) are applied to the fiber reinforcement (2), this fiber reinforcement (2) is activated using low temperature or pressure plasma in a gaseous environment with gases/em Co, O2 , Ar, N2, CO2, NH3, Ne, He or monomers based on silanes, siloxanes or acrylates or their combinations. The method of manufacturing a structural composite material according to claim 8, characterized by the fact that after the nanofibers (11) are applied to the fiber reinforcement (2), these nanofibers (11) are activated using plasma at a low temperature or pressure in a gaseous environment with gases/em Co, O2, Ar, N2, CO2, NH3, Ne, He or monomers based on silanes, siloxanes or acrylates or combinations thereof. The method of manufacturing a structural composite material according to claims 8, 9 or 10, characterized in that the process of applying the nanofibers (11) to the fiber reinforcement (2) is carried out by means of electrostatic or centrifugal spinning of the layer (1) of the nanofibers (11) or lamination of the spun layer ( 1) nanofibers (11) using pressure rollers. 5 drawings - 10CZ 307683 B6 List of relationship tags: 1 - 11 - 2- 21 - 22- 3- 4- 5- layer of polymer nanofibers polymer nanofiber fiber reinforcement inner fiber of fiber reinforcement outer fiber of fiber reinforcement impregnation material separation film made of polyethylene separation paper with polyethylene or silicone