A polymer blend refers to a mixture of two or more homopolymers or copolymers. The polymer components in the polymer blend are mainly physical bonding, so the polymer blend is distinguished from the copolymerized polymer. However, in polymer blends, there are inevitably a small amount of chemical bonds between different polymer macromolecules. For example, in the process of melt mixing under the action of strong shearing force, the molecular free radicals, thereby forming small amounts of block or graft copolymers. In addition, the reaction compatibilization measures adopted in recent years to strengthen the interfacial adhesion between the components involved in the blended polymer also inevitably introduce chemical bonds between the components. There are many types of polymer blends, but generally refer to blends of plastics with plastics and the incorporation of rubber into plastics. For the blend system with a small amount of rubber mixed in the plastic, it is generally called rubber toughened plastic because of its great improvement in impact performance. The types of polymer blends are divided into binary and multi-polymer blends according to the number of polymer components contained; according to the name of the matrix resin in the polymer blends, they can be divided into polyolefin blends, polyvinyl chloride Blends, polycarbonate blends, polyamide blends, etc.; according to performance characteristics, there are polymer blends such as high temperature resistance, low temperature resistance, flame retardant, and aging resistance.
Although plastic has many excellent properties, it has many disadvantages compared with metal materials. In some fields with high comprehensive performance requirements, it is difficult for a single plastic to meet the requirements. Therefore, the purpose of blending modified plastics is as follows.
①Improve the comprehensive performance of plastics, pvc pe wax.
②Improve the mechanical properties of plastics, such as strength, low temperature toughness, etc.
③Improve the heat resistance of plastics. The heat distortion temperature of most plastics is not high, and for some parts that work at a certain temperature, general-purpose plastics are incompetent.
④ Improve processing performance. For example, the molding processability of PPO is poor, and its processing fluidity is greatly improved after adding PS modification.
⑤Reduce water absorption and improve product dimensional stability. For example, the water absorption of polyamide is relatively large, which causes the dimensional change of the product.
⑥ Improve the combustion resistance of plastics. Most plastics are flammable materials, and the safety of electrical and electronic equipment is low. Through flame retardant modification, the safety of materials has been improved.
⑦Reduce the cost of materials. Plastics, especially engineering plastics, are expensive. The blending and modification of general plastics and engineering plastics not only reduces the cost of materials, but also improves the molding processability.
⑧ Realize the functionalization of plastics and improve their performance. For example, plastics have low electrical conductivity. For some applications that require anti-static and electrical conductivity, they can be blended with conductive polymers to obtain anti-static functions, conductive functions and electromagnetic shielding. Functional plastic materials to meet the requirements of electronics, home appliances, communications, military, etc.
In short, through blending and modification, the comprehensive properties of plastics can be improved, the varieties of plastics can be increased under the condition of relatively low investment, the use of plastics can be expanded, the cost of plastics can be reduced, and the high performance, refinement, functionalization, Specialization and serialization promote the development of the plastics industry and the polymer material industry, as well as the development of high-tech industries such as automobiles, electronics, electrical appliances, home appliances, communications, military, aerospace, etc.
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