The synthesis of polyvinyl chloride PVC from vinyl chloride monomer VCM involves a polymerization reaction, specifically a free radical chain-growth polymerization. The reaction mechanism can be broken down into three main steps: initiation, propagation, and termination.1. Initiation:In this step, a free radical initiator, such as an organic peroxide or an azo compound, is used to generate a reactive free radical species. The initiator undergoes homolytic cleavage, producing two free radicals. These radicals can then react with the vinyl chloride monomer, breaking the double bond and forming a new free radical on the vinyl chloride molecule.Initiator 2 Free RadicalsFree Radical + CH2=CHCl VCM CH2-CHCl VCM Radical 2. Propagation:The VCM radical generated in the initiation step can now react with another vinyl chloride monomer, breaking its double bond and forming a new VCM radical with an extended chain. This process continues, with the growing polymer chain reacting with more VCM molecules, leading to the formation of polyvinyl chloride.CH2-CHCl VCM Radical + CH2=CHCl VCM CH2-CHCl-CH2-CHCl PVC Radical This propagation step can occur multiple times, allowing the polymer chain to grow in length.3. Termination:The polymerization reaction is terminated when two free radicals react with each other, forming a covalent bond and ending the chain growth. This can occur through several mechanisms, such as combination two growing polymer chains reacting with each other or disproportionation transfer of a hydrogen atom from one radical to another .CH2-CHCl-CH2-CHCl PVC Radical + CH2-CHCl-CH2-CHCl PVC Radical CH2-CHCl-CH2-CHCl-CH2-CHCl-CH2-CHCl PVC Overall, the reaction mechanism for the synthesis of polyvinyl chloride from vinyl chloride monomer involves a free radical chain-growth polymerization process, with initiation, propagation, and termination steps.