Non-polar thermoplastic resins, such as PP (polypropylene), have saturated surface groups and no polarity, and are difficult to react with the organophilic groups of the coupling agent, so it is difficult to obtain a good modification effect. For this reason, on the one hand, the interfacial bonding strength can be improved by matrix modification. For example, Zhang Zhiqian et al. added maleic anhydride graft-modified polypropylene to the polypropylene matrix, which significantly improved the interfacial strength of the composite material; The polymer chains are grafted on the surface of the fiberglass , and a flexible layer is formed on the interface of the composite material through the polymer chains, so that the interfacial stress generated by the composite material after the external force can be effectively relaxed, so its impact resistance is significantly improved, thus Improve the impact resistance of the material. The method of grafting is generally to treat the fiberglass with a coupling agent to form an active center on its surface or introduce a functional group, which can initiate a polymerization reaction to form a polymer chain. Treat the surface of the glass fiber with a silane coupling agent containing a peroxygen bond, and then treat it by polycondensation. Xue Zhiyun used ozone to pretreat the surface of  fiberglass  impregnated with MAC (surface treatment agent), and used ozonation to form an activation center on the surface of fiberglass, which can effectively initiate the polymerization of methyl methacrylate, so that the polymer resin grafted onto the fiber surface. The grafted methyl methacrylate has good compatibility with the resin matrix, and the comprehensive performance of the composite material is significantly improved. Yang Weijiang first coated the surface of the fiber with a coupling agent containing peroxide bonds through impregnation treatment, and then grafted polystyrene on the surface of the fiber. The resin-based composite material thus prepared had strong interfacial bonding. Surface grafting polymer is a method of  fiberglass  surface functionalization. Through design and selection of grafts to achieve strong interfacial bonding with the matrix, it can significantly improve

The comprehensive performance of composite materials, the disadvantage is that the process is more complicated. After the silane coupling agent is grafted onto the surface of the fiberglass by chemical bonding, the treatment method of re-grafting the grafted silane coupling agent or other small molecules is the surface secondary grafting treatment, which is the surface treatment of the glass fiber. a new method of . Li et al first treated the surface of glass fiber with 3-bromopropyl trichlorosiloxane to form a chemical bond with the surface of the  fiberglass , and then reacted with bromine in 3-bromopropyl trichlorosiloxane with aniline, and then Grafting polyaniline on aniline, this method of surface secondary grafting treatment is very worthy of reference and in-depth study by composite material researchers.