Polyvinyl chloride is a polymer material that uses a chlorine atoms to replace one hydrogen atom in polyethylene, and is a amorphous polymer containing a small amount of crystalline structure. The structure of this material is as follows: [Chich 2. PVC is a linear polymer with the head-tail structure of VCM monomer. The carbon atoms are arranged in a sawtooth shape, and all the atoms are connected by σ bonds. All carbon atoms are SP3 hybrid.
In the PVC molecule chain, there is a short and regular structure. With the decrease of polymerization reaction temperature, the regularity of the regulation is improved. In the macromolecular structure of polyvinyl chloride, the structure of head, chain, double bond, allyl chloride and tert-chlorine are the unstable structures, which make the heat-resisting deformation and aging-resistance weak. After pretending to be cross-linked, it can be eliminated.
Cross-linking is divided into radiation crosslinking and chemical crosslinking.
1. Radiation crosslinking. The use of high-energy rays, generally the electron rays generated by the radiation or electron acceleration generated by a cobalt 60 source, mainly uses the latter. The cross-linking agent (two or more carbon-carbon double bond structure monomers) is then supported. But the operation is very difficult, the equipment requirements are high.
2. Chemical cross-linking. Cross-linking was performed using Triazole diamine salts (FSH), and the crosslinking mechanism was substituted for the combination of amine and sulfhydryl radicals in the attack of carbon chloride polar bonds. Cross-linked products resistance to ultraviolet, solvent resistance, temperature, impact toughness and other properties will be comprehensively upgraded.