Chemical method for activating aramid fiber surface

Abstract

The invention relates to a chemical method for activating aramid fiber surface and the method adopts aramid fiber as activated object. The method comprises the following steps: using a large amount of benzene rings in the molecular chains of aramid fiber to perform Friedel-Crafts reaction with epichlorohydrin, grafting epichlorohydrin to aramid fiber surface to form o-chlorohydrin side chains, and then using alkaline solution to perform epoxidation and obtain active side chains. The specific steps are as follows: firstly drying aramid fiber, epichlorohydrin and anhydrous aluminium chloride, performing a grafting reaction, using acetone to soak, secondly performing epoxidation reaction, washing with distilled water, and finally drying aramid fiber to obtain aramid fiber with activated surface. The chemical method can increase the surface activity of aramid fiber under the premise of not damaging the entity structure, have the advantages that the cost is low, the process operability is strong, the surface activation effect is good, the activation does not have degradation effect and the social benefit is good, and be applicable to batch industrial production.

Description

technical field [0001] The invention relates to the technical field of aramid fiber surface activation, in particular to a chemical method for aramid fiber surface activation. Background technique [0002] With its low density, high strength, high stiffness, high heat resistance and good chemical environment resistance, aramid fiber is used as an excellent reinforcing material, and is widely used in advanced high-tech fields such as aviation and aerospace. In the composite material technology, however, the highly oriented and crystalline structure formed in the liquid crystal spinning process causes the aramid fiber to exhibit a strong surface chemical inertness, which greatly reduces the interfacial bonding strength between it and the resin matrix, thereby affecting The comprehensive mechanical properties of composite materials have had a great negative impact. Therefore, the research on the surface activation of aramid fibers has always been a hot and difficult point in th...

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Problems solved by technology

[0002] With its low density, high strength, high stiffness, high heat resistance and good chemical environment resistance, aramid fiber is used as an excellent reinforcing material, and is widely used in advanced high-tech fields such as aviation and aerospace. In the composite material technology, however, the highly oriented and crystalline structure formed in the liquid crystal spinning process causes the aramid fiber to exhibit a strong surface chemical inertness, which greatly reduces the interfacial bonding strength between it and the resin matrix, thereby affecting The comprehensive mechanical properties of composite materials have had a great negative impact. Therefore, the research on the surface activation of aramid fibers has always been a hot and difficult point in the field of advanced composite materials.

[0003] The existing surface activation methods of aramid fibers at home and abroad mainly include three methods: physics, chemistry and the comprehensive application of the two, but most of them are still used as experimental research and cannot be used in large-scale industrial applications. The reason is that physical methods mainly use Ultrasonic vibration causes cavitation of the liquid near the fiber surface, and the energy released by the cavitation can peel off the weak layer on the fiber surface and reduce the stress concentration point, but this method does not solve the essential factors that affect the interfacial bonding strength of composite materials , that is, chemically inert, so the activation effect is poor

The chemical method includes two ways: one is to use the corrosion effect of strong oxidizing acid to peel off the weak layer on the surface of the fiber and form etching pits and grooves, so as to use the physical inlay and riveting effect of resin solidified in the pits and grooves, Increase the interface bonding strength between the aramid fiber and the resin matrix. The disadvantage of this approach is that it is difficult to control the degree of corrosion and the depth of etching, and often directly destroys the bulk structure of the aramid fiber, resulting in a significant decrease in its bulk strength; It is to use chemical grafting reaction to introduce active groups on the surface of aramid fiber, so as to form a stable chemical bond between aramid fiber, resin and curing agent, and improve the interfacial bonding strength of composite materials, but the traditional chemical method mainly uses The hydrogen atom in the amide group in the aramid molecular chain is used as the reaction center, but the reactivity of the hydrogen atom is severely deactivated by the strong conjugation of the carbonyl and benzene rings around it, and the steric hindrance effect of the benzene ring , the reactivity is further reduced, so the activation effect is poor

The comprehensive application of physical and chemical methods is mainly to use physical means such as plasma or high-energy rays to generate short-term active centers such as free radicals or charged particles on the fiber surface, and then use chain chemical reactions to graft active short chains on the fiber surface. The disadvantage of the method is that the cost is too high, the process operability is poor, and the activation effect has a degradation effect.

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