A comprehensive review of synthesis, properties and modification of several common polyethylenes

Polyethylene (PE) has good chemical stability and corrosion resistance and is one of the top five synthetic resins, widely used in the manufacture of films and fibers. However, with the development of society, simple PE products can no longer meet people's demands for performance. This article describes the performance, production methods, and several methods and effects of PE modification of different kinds of PE. The performance of PE is related to the way it is processed and the length of its branches and the number of branches. The shorter the length of the branch chain, the less the number of long branch chains and short branch chains, the higher the density, the stronger the crystallinity, the higher the tensile strength, the tensile modulus, and hardness, and the higher the melting point. The larger the molecular weight, the more branched chains, the tighter the entanglement between the molecular chains, and the greater the viscosity of the material. The fewer the branch chains, the shorter the length of the branch chains, and the lower the pressure and temperature required for processing. In the third part, this article describes the enhanced interface compatibility of materials, improved processing properties, reduced costs, and improved mechanical properties such as compliance and stress cracking by physical modification (blending modification, filling modification, enhanced modification) and chemical modification (crosslinking modification, graft modification, copolymerization modification). It also describes new modified technologies such as metallocene catalysis and nanomaterial filling that improve material properties while becoming more environmentally friendly. This paper expects to be able to develop PE materials that meet social needs based on the specific properties of PE and the way of modification, guided by different needs for materials.