The fiber-reinforced body in the composite material is divided into two major categories of inorganic fiber reinforcement and organic fiber reinforcement. Inorganic fibers include glass fibers, carbon fibers, boron fibers, and silicon carbide fibers; organic fibers include aramid fibers, nylon fibers, and polyolefin fibers.

Glass fiber is the most widely used reinforcement in fiber-reinforced composites. It can be used as a reinforcing material for organic polymers or inorganic non-metals and composites. It has the characteristics of low cost, non-combustion, heat resistance, chemical resistance, high tensile strength and impact strength, low elongation at break, good thermal insulation and good insulation properties. Silica and metal oxides are the main components of amorphous inorganic fibers.

The application of glass fiber in the world to enhance the modification of thermoplastic plastics began in the 50's. In 1952, the American company first began to develop a long glass fiber reinforced nylon 6, and achieved industrial production in 1956. The extrusion coating method is used, similar to the cable coating method and the like. The first domestic production of glass fiber-reinforced nylon products was the Suzhou No. 1 Plastics Factory. In 1969, it achieved an annual production capacity of 100 tons. The literature describes a method of producing reinforced plastics directly from a resin melt at the discharge outlet of a polymerizer and directly coating glass fiber filaments with a machine head. This method saves investment and energy consumption, and also avoids resin extrusion and granulation. Brings down the performance index, suitable for use in the production of reinforced plastic varieties. However, the reinforced plastic particles produced by the process or can contain higher amounts of monomers than extrusion coating methods, affecting the quality of plastic products.

After the thermoplastic resin is reinforced with glass fiber, the strength, modulus, impact resistance and heat resistance are all improved. When fiber is reinforced, fiber length is one of the main factors that determine fiber-reinforced composite materials. The strength, modulus, impact resistance, creep resistance, fatigue resistance, wear resistance, and heat resistance of the long glass fiber-reinforced nylon are improved as compared with the short glass fiber reinforced method, thereby further broadening its application range. . Long-glass fiber reinforced PA6 has great potential for development in the automotive, mechanical, electrical, and military industries.

The length of the glass fiber is not the only factor determining the performance of the fiber composite material. The impregnation condition of the fiber, the distribution of the fiber in the matrix, the content of the fiber, and the interfacial bonding strength between the fiber and the matrix all have an important influence on the performance of the composite material. Glass fiber plays a reinforcing role in the structure of the skeleton in nylon. When the load is applied, due to the axial transmission of the glass fiber, the stress is rapidly diffused to prevent the growth of the crack. Therefore, the increase of the glass fiber content increases the mechanical properties of the nylon. Its addition makes the hindrance of polymer macromolecular segments in the interfacial layer between the fiber and the matrix resin increase, the glass transition temperature of the material increases, and the macroscopically manifests as the increase of the heat distortion temperature. In addition, as the content of glass fiber increases, the melt flow rate and elongation at break of the composite material decrease, while the density and hardness increase. This also shows that the material's pressure resistance is improved. However, when the glass fiber content is too high, the fluidity of the prepolymer is reduced, which brings great difficulties to the manufacturing process. The literature considers that the content of glass fiber in PA66 system is best at 30%. At this time, the tensile strength of PA66 system is greater than 100MPa, and the notched impact strength is greater than 9KJ/m2. Gao Zhiqiu et al. studied long glass fiber reinforced nylon 6 composites and found that at a glass fiber content of 32.2% and a pellet length of 10 mm, the composite has a tensile strength of 208.4 MPa, a bending strength of 269.5 MPa, and a bending elastic modulus. The amount is 9.34Gpa. The notched impact strength was 29 KJ/m2 and the impact strength was 63.4 KJ/m2. The mechanical properties are significantly better than those of short glass-reinforced PA6 composites. Ge Shirong et al. studied the tribological properties of glass fiber reinforced nylon composites and suggested that the reinforcing effect was better when the fiber mass fraction was between 25% and 30%.

Glass fiber reinforced nylon 66 has the following advantages compared to pure PA: mechanical strength, good rigidity (elastic modulus is more than 1 times greater than PC); heat distortion temperature is 50-60°C higher than PA; especially valuable is dynamic fatigue resistance Good, because it is quite reliable as a structural material; in addition, its internal stress is very small and there is no stress cracking. The deficiency of glass fiber reinforced nylon is that the impact toughness is not as good as that of pure PA; due to the infiltration of glass fiber, the gloss of the part is not good, and the glass fiber is exposed when the processing is inadvertent; especially the anisotropy of the molding shrinkage, As a result, warpage of the parts is likely to occur, which brings certain difficulties to the molding process, the parts and the mold design.

In glass fiber composites, glass fiber is the main bearing component. Since the wave fiber is composed of a mixture of alkali metal oxides with strong water absorption dispersed in the SiO2 network, the glass fiber is exposed to the atmosphere. The surface will adsorb a layer of water molecules. When the composite material is formed, the water present at the glass fiber-matrix interface will not only affect the adhesion of the glass fiber to the resin matrix, but also will damage the fiber and degrade the resin, thereby reducing the performance of the composite material. Therefore, its surface treatment has become a key technology and an important process for the manufacture of composite materials. Through surface treatment, a strong bond can be formed between the glass fiber and the synthetic resin, so that various properties can be improved. In general, the surface treatment means that the surface of the glass fiber is treated with a coupling agent so that it can be well combined with the substrate.