阅读说明：本技术 多巴胺-聚乙烯亚胺-纳米颗粒联合改性聚四氟乙烯-芳纶混纺织物的方法 (Method for modifying polytetrafluoroethylene-aramid fiber blended fabric by combining dopamine-polyethyleneimine-nanoparticles ) 是由 袁军亚 张招柱 杨明明 姜葳 赵鑫 于 2019-11-20 设计创作，主要内容包括：本发明公开了一种多巴胺-聚乙烯亚胺-纳米颗粒联合改性聚四氟乙烯-芳纶混纺织物的方法,是将聚四氟乙烯-芳纶混纺织物、盐酸多巴胺、聚乙烯亚胺、纳米颗粒加入到三羟甲基-氨基甲烷/盐酸缓冲溶液中,搅拌、超声分散均匀后在室温条件下持续搅拌反应2~24 h；待反应完成后,将混纺织物取出,用去离子水充分洗涤以除去表面未反应的杂质,然后在真空烘箱中干燥,得到表面改性的聚四氟乙烯-芳纶混纺织物。通过本发明改性在纤维表面构筑一层有机-无机杂化功能涂层,因而在混纺织物表面同时引入活性功能基团和更大的表面粗糙度,可以通过化学键接和机械联锁,提高混纺织物与酚醛树脂基体之间的界面粘附性能。(The invention discloses a method for modifying a polytetrafluoroethylene-aramid fiber blended fabric by combining dopamine-polyethyleneimine-nanoparticles, which comprises the steps of adding the polytetrafluoroethylene-aramid fiber blended fabric, dopamine hydrochloride, polyethyleneimine and nanoparticles into a trihydroxymethyl-aminomethane/hydrochloric acid buffer solution, stirring, ultrasonically dispersing uniformly, and then continuously stirring and reacting for 2-24 hours at room temperature; and after the reaction is finished, taking out the blended fabric, fully washing the blended fabric by using deionized water to remove unreacted impurities on the surface, and drying the fabric in a vacuum oven to obtain the surface modified polytetrafluoroethylene-aramid blended fabric. The surface of the fiber is modified by the method to form an organic-inorganic hybrid functional coating, so that active functional groups and larger surface roughness are introduced into the surface of the blended fabric, and the interfacial adhesion performance between the blended fabric and a phenolic resin matrix can be improved through chemical bonding and mechanical interlocking.)

1. The method for modifying the polytetrafluoroethylene-aramid fiber blended fabric by combining dopamine-polyethyleneimine-nanoparticles comprises the steps of adding the polytetrafluoroethylene-aramid fiber blended fabric, dopamine hydrochloride, polyethyleneimine and nanoparticles into a trihydroxymethyl-aminomethane/hydrochloric acid buffer solution, stirring, ultrasonically dispersing uniformly, and then continuously stirring and reacting for 2-24 hours at room temperature; and after the reaction is finished, taking out the blended fabric, fully washing the blended fabric by using deionized water to remove unreacted impurities on the surface, and drying the fabric in a vacuum oven to obtain the surface modified polytetrafluoroethylene-aramid blended fabric.

2. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 1, wherein the method comprises the following steps: the dosage of the dopamine hydrochloride is 0.05-0.5 time of the mass of the polytetrafluoroethylene-aramid fiber blended fabric.

3. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 1, wherein the method comprises the following steps: the addition amount of the polyethyleneimine is 0.1-5 times of the mass of the dopamine hydrochloride.

4. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 1, wherein the method comprises the following steps: the dosage of the nano particles is 0.1-5 times of the mass of the dopamine hydrochloride.

5. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 1, wherein the method comprises the following steps: the nano-particles are one of metal oxide, metal carbide, metal boride, carbon nano-tubes, graphene and silicon dioxide.

6. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 5, wherein the method comprises the following steps: the metal oxide is one of zinc oxide, aluminum oxide, titanium oxide, copper oxide, zirconium oxide and iron oxide.

7. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 5, wherein the method comprises the following steps: the metal carbide is one of titanium carbide, tungsten carbide and zirconium carbide.

8. The method for modifying a polytetrafluoroethylene-aramid blended fabric by combining dopamine-polyethyleneimine-nanoparticles according to claim 5, wherein the method comprises the following steps: the metal boride is one of titanium boride, zirconium boride and aluminum boride.

9. The method for modifying the polytetrafluoroethylene-aramid blended fabric by combining the dopamine-polyethyleneimine-nanoparticles according to any one of claims 1 to 8, wherein the method comprises the following steps: in a trihydroxymethyl-aminomethane/hydrochloric acid buffer solution, the concentration of dopamine hydrochloride is 1-3 mg/mL.

10. The method for modifying the polytetrafluoroethylene-aramid blended fabric by combining the dopamine-polyethyleneimine-nanoparticles according to any one of claims 1 to 8, wherein the method comprises the following steps: the pH value of the trihydroxymethyl-aminomethane/hydrochloric acid buffer solution is 6-10.

Technical Field

The invention relates to a surface modification method of a polytetrafluoroethylene-aramid fiber blended fabric, in particular to a method for jointly modifying the polytetrafluoroethylene-aramid fiber blended fabric by dopamine-polyethyleneimine-nanoparticles, and belongs to the technical field of surface modification of nano materials and fibers.

Background

The fiber reinforced polymer matrix composite has the advantages of light weight, high strength, outstanding fatigue resistance, corrosion resistance, excellent designability and the like, so the fiber reinforced polymer matrix composite is widely applied to the high-end manufacturing fields of aerospace, automobiles, weaponry and the like. In the blended fabric, because different types of fibers are introduced in the weaving process, the blended fabric has the advantages and properties of different fibers, and therefore, the blended fabric draws more and more attention of researchers. At present, a blended fabric material formed by mixing and weaving polytetrafluoroethylene fibers serving as a lubricating phase and aramid fibers is considered as an ideal material of a bearing pad due to the combination of the excellent lubricating property of the polytetrafluoroethylene fibers and the high specific strength of the aramid fibers. However, both polytetrafluoroethylene and aramid fibers have relatively smooth surfaces and lack reactive groups, and thus interfacial adhesion to the resin matrix can only be relied upon by weak van der waals forces. The weak fiber/resin interface adhesion performance prevents external stress on the resin matrix from being effectively transferred to the fabric reinforcing phase, thereby forming stress concentration at the interface and damaging the structural integrity of the composite material. In particular, in the friction process, stress-induced micro-cracks at the interface are expanded to the surface of the resin, the resin matrix begins to peel off under the action of shear stress and pressure stress, and the reinforcing fibers in the resin matrix are cut off and pulled out, so that the application range and the service life of the gasket material are greatly limited. Therefore, modifying the surface of the polytetrafluoroethylene-aramid blended fabric, introducing active functional groups on the surface of the fiber or constructing larger surface roughness so as to improve the interface adhesion performance of the fabric and the phenolic resin matrix is very important.

In recent years, the interface performance of the fiber and the resin matrix is greatly concerned by the rapid development of the composite material technology, and various surface modification technologies are applied to the improvement of the interface performance, including chemical vapor deposition, physical vapor deposition, plasma etching, high-energy radiation, chemical grafting, adhesive coating and the like. However, most of these modification methods involve expensive experimental equipment, complicated reaction conditions or high reaction temperature, and thus it is necessary to find a simple and mild method for modifying the fiber surface. In addition, because the surface characteristics of the polytetrafluoroethylene fiber and the aramid fiber are different, the modification method used is required to be simultaneously suitable for the two different fibers, and the original mechanical strength of the fibers is also required to be maintained, which provides great challenges for the conventional fiber modification method.

Disclosure of Invention

The invention aims to provide a method for modifying a polytetrafluoroethylene-aramid fiber blended fabric by combining dopamine-polyethyleneimine-nanoparticles so as to optimize the interfacial adhesion performance of the polytetrafluoroethylene-aramid fiber blended fabric and a phenolic resin-based composite material.

Surface modification method for polytetrafluoroethylene-aramid fiber blended fabric

The method for modifying the polytetrafluoroethylene-aramid fiber blended fabric by combining the dopamine-polyethyleneimine-nanoparticles comprises the steps of adding the polytetrafluoroethylene-aramid fiber blended fabric, dopamine hydrochloride, polyethyleneimine and nanoparticles into a trihydroxymethyl-aminomethane/hydrochloric acid buffer solution, stirring, ultrasonically dispersing uniformly, and then continuously stirring and reacting for 2-24 hours at room temperature; and after the reaction is finished, taking out the blended fabric, fully washing the blended fabric by using deionized water to remove unreacted impurities on the surface, and drying the fabric in a vacuum oven to obtain the surface modified polytetrafluoroethylene-aramid blended fabric.

The pH value of the trihydroxymethyl-aminomethane/hydrochloric acid buffer solution is 6-10. In a trihydroxymethyl-aminomethane/hydrochloric acid buffer solution, the concentration of the dopamine hydrochloride is 1-3 mg/ml.

The polydopamine formed by oxidative autopolymerization of the dopamine hydrochloride in the modification process has extremely strong surface adhesion performance, and can be coated on the surface of the polytetrafluoroethylene-aramid fiber blended fabric. The dosage of the dopamine hydrochloride is 0.05-0.5 time of the mass of the polytetrafluoroethylene-aramid fiber blended fabric.

The polyethyleneimine is introduced to promote the polymerization of dopamine hydrochloride, and is copolymerized with dopamine through Michael addition and Schiff base reaction, so that the polymerization rate of dopamine, and the uniformity, compactness and active group content of the obtained coating are improved. The addition amount of the polyethyleneimine is 0.1-5 times of the mass of the dopamine hydrochloride.

The introduction of the nano particles is to anchor the nano particles on the surface of the polytetrafluoroethylene-aramid fiber blended fabric by utilizing the extremely strong adhesive property of the polydopamine-polyethyleneimine hybrid coating, construct an organic-inorganic hybrid functional coating, improve the surface roughness of the modified fabric, and play a role in modulus buffering between the fabric and a resin matrix. The nano-particles are one of metal oxides (zinc oxide, aluminum oxide, titanium oxide, copper oxide, zirconium oxide and iron oxide), metal carbides (titanium carbide, tungsten carbide and zirconium carbide), metal borides (titanium boride, zirconium boride and aluminum boride), carbon nano-tubes, graphene and silicon dioxide. The dosage of the nano particles is 0.1-5 times of the mass of the dopamine hydrochloride.

Secondly, the influence of surface modification on the interface performance and the mechanical property of the fabric

1. Interfacial adhesion performance

The test method comprises the following steps: the interfacial adhesion performance test of the blended fabric composite material was performed on an electronic fabric tensile machine (YG 026D) according to GB/T2790-.

Fig. 1 shows the interfacial adhesion performance of unmodified, dopamine-polyethyleneimine codeposition modified and dopamine-polyethyleneimine-nanoparticle combined modified polytetrafluoroethylene-aramid blended fabric composite material. As shown in figure 1, after the blended fabric is jointly modified by dopamine-polyethyleneimine-nanoparticles, the interfacial adhesion performance of the composite material is greatly improved. As can be seen by observing the cross section and the peel-off surface of the fabric composite material (figure 2), the gaps between the fibers and the resin are larger and the resin peel-off surface is smoother in the cross section of the unmodified fabric composite material, which indicates that the interfacial adhesion performance of the unmodified fabric and the resin matrix is weaker. After the fiber fabric is subjected to combined modification by dopamine-polyethyleneimine-nanoparticles, the interface gap between the fiber and the resin is obviously reduced, and meanwhile, part of broken fibers remain on the resin stripping surface, so that the interface performance of the polytetrafluoroethylene-aramid fiber blended fabric composite material after the fiber fabric is subjected to combined modification is further proved to be effectively improved.

2. Tensile Properties of the blended Fabric

The test method comprises the following steps: the tensile strength of the blended fabric was also performed on an electronic fabric strengthener (YG 026D).

And testing the tensile property of the dopamine-polyethyleneimine-nanoparticle combined modified polytetrafluoroethylene-aramid blended fabric, and comparing the tensile property with that of the unmodified blended fabric. Fig. 3 shows the tensile strength of the blend fabric without modification, with dopamine-polyethyleneimine codeposition modification and dopamine-polyethyleneimine-nanoparticle combination modification. The results in fig. 3 show that the mechanical properties of the blended fabric are not significantly reduced after the blended fabric is jointly modified by dopamine-polyethyleneimine-nanoparticles.

In conclusion, the surface modification method of the polytetrafluoroethylene-aramid blended fabric provided by the invention has the following advantages:

1. according to the surface modification method of the polytetrafluoroethylene-aramid blended fabric, an organic-inorganic hybrid functional coating is constructed on the surface of the fiber, so that active functional groups and larger surface roughness can be introduced into the surface of the blended fabric simultaneously, a double promotion effect is provided for improving the interface performance of a composite material, and the damage to the mechanical property of the blended fabric is avoided;

2. according to the surface modification method of the polytetrafluoroethylene-aramid blended fabric, the construction of the organic-inorganic hybrid functional coating can be realized through one-step reaction, and the method has the characteristics of simplicity in operation, mild reaction conditions, high efficiency and the like;

3. the surface modification method of the polytetrafluoroethylene-aramid blended fabric does not have specific substrate selectivity, so that the polytetrafluoroethylene-aramid blended fabric can be deposited and coated on the surfaces of almost all fibers, and can be used for solving the problem of fiber interface adhesion in a wider range.

Drawings

Fig. 1 shows the interfacial adhesion performance of unmodified, dopamine-polyethyleneimine codeposition modified and dopamine-polyethyleneimine-nanoparticle combined modified polytetrafluoroethylene-aramid blended fabric composite material.

FIG. 2 shows the cross section and the stripping surface appearance of an unmodified, dopamine-polyethyleneimine codeposition modified and dopamine-polyethyleneimine-nanoparticle combined modified polytetrafluoroethylene-aramid blended fabric composite material.

Fig. 3 shows the tensile strength of the blend fabric without modification, with dopamine-polyethyleneimine codeposition modification and dopamine-polyethyleneimine-nanoparticle combination modification.

Detailed Description

The surface modification method and modification effect of the polytetrafluoroethylene-aramid blended fabric of the invention are further explained by the following specific examples. Wherein the interface bonding strength of the unmodified polytetrafluoroethylene-aramid fiber blended fabric and the phenolic resin matrix is 3.1N/mm; the blended fabric had a tensile strength of 608N.