Polyvinyl chloride is a polymer material that uses a chlorine atom to replace a hydrogen atom in polyethylene, and is an amorphous polymer containing a small amount of crystalline structure. The structure of this material is as follows: [―ch2―chcl―]n. PVC is a linear polymer with the most of VCM monomer in the head-tail structure. The carbon atoms are jagged and all atoms are connected by σ bonds. All carbon atoms are SP3 mixed.
There is a short inter regulation structured structure in the PVC molecular chain. With the decrease of polymerization temperature, the regularity of inter regulation is improved. In the structure of polyvinyl chloride, there are some unstable structures such as head structure, branched chain, double bond, allyl chloride, tert-chlorine, etc., which make heat-resistant deformation and anti-aging. This kind of shortcoming can be eliminated after the pretended cross-linking.
Cross-linking is divided into radiation crosslinking and chemical cross-linking.
1. Radiation cross-linking. The use of high-energy rays, typically produced by radiation from cobalt 60 sources or by electron-generated electron rays, is mainly used for the latter. The cross-linking agent (two or more monomers of carbon-carbon double bond structure) is assisted. But the operation is very difficult, the equipment requirements are high.
2. Chemical cross-linking. The cross-linking mechanism of triazole diamine Salt (FSH) was substituted for the combination of amine and sulfhydryl to attack carbon-chlorine polarity. Cross-linked products UV resistance, solvent resistance, temperature, impact toughness and other properties will be fully upgraded.