Polyethylene (PE) is a thermoplastic plastic formed by the coordination polymerization or free radical polymerization of ethylene monomers. It can be regarded as “the most widely produced general-purpose plastic substrate in the world” - it can adjust the crystallinity and mechanical properties from low density to high density through the simple repetitive methylene main chain (-CH₂-CH₂-)n and different branching structures. It also has excellent water resistance, chemical resistance, electrical insulation, and good low-temperature toughness. According to the polymerization method and branching degree, it is mainly divided into low-density polyethylene (LDPE, soft and transparent), high-density polyethylene (HDPE, rigid and resistant to the environment), and linear low-density polyethylene (LLDPE, high tear strength), and is widely used in film packaging, plastic bottles and cans, pipes, cable insulation, storage tanks, toys and daily necessities, etc., covering almost all aspects of daily life and industrial fields.