The double bond in the unsaturated polyester polymerizes with the double bond in the crosslinker to form an insoluble and infusible crosslinked network, and the network contains two polymer molecular chain structures. The network main body is composed of random coils of unsaturated polyester molecular chains, and a styrene copolymer molecular chain interspersed therein to connect and fix the unsaturated polyester molecular chains to form a huge net. The average molecular mass of the unsaturated polyester molecular chain in the network is 1000~3000. The average molecular mass of the molecular chain of styrene copolymer can reach 8000~14000. The average molecular weight of the entire network structure is 10,000~30,000. If the network molecular mass is less than 10,000, it will directly affect the mechanical properties of the product, such as strength, elasticity and toughness. The long-lived free-radical unsaturated polyester resin cross-linking network of unsaturated polyester resin cross-linking network has certain characteristics in the polymerization process and residual rate change of unsaturated polyester and styrene in the curing process. Experiments show that no matter whether the polyester resin cross-linking network is perfect or not, it will produce some dead spots of steric hindrance that cannot be terminated by free radicals, forming long-lived free radicals. Due to the presence of long-lived free radicals, the cross-linking reaction can still proceed after the unsaturated polyester resin is cured.
