The synthesis of polyvinyl chloride PVC from vinyl chloride monomer VCM involves a process called free radical polymerization. Here's the step-by-step mechanism involved in this process:1. Initiation: a. A free radical initiator, such as benzoyl peroxide or azobisisobutyronitrile AIBN , is added to the reaction mixture containing vinyl chloride monomer. b. The initiator undergoes homolytic cleavage, producing two free radicals. c. One of the free radicals reacts with a vinyl chloride monomer, breaking the double bond and forming a new free radical on the monomer.2. Propagation: a. The newly formed free radical on the vinyl chloride monomer reacts with another vinyl chloride monomer, breaking its double bond and forming a new free radical on the second monomer. b. This process continues, with the growing polymer chain reacting with more vinyl chloride monomers, resulting in the formation of polyvinyl chloride.3. Termination: a. The growing polymer chain can be terminated by various mechanisms, such as combination two free radicals react with each other or disproportionation one free radical abstracts a hydrogen atom from another, forming a double bond . b. Termination results in the formation of the final PVC polymer.To control the degree of polymerization and affect the yield and quality of the final product, several factors can be manipulated:1. Initiator concentration: By adjusting the concentration of the initiator, the number of free radicals generated can be controlled, which in turn affects the degree of polymerization and the molecular weight of the PVC.2. Reaction temperature: The rate of polymerization is temperature-dependent. Higher temperatures increase the rate of polymerization and can also affect the molecular weight distribution of the final product.3. Reaction time: The degree of polymerization can be controlled by adjusting the reaction time. Longer reaction times result in higher degrees of polymerization and higher molecular weight PVC.4. Monomer concentration: The concentration of vinyl chloride monomer in the reaction mixture can also affect the degree of polymerization and the molecular weight of the PVC.5. Chain transfer agents: The addition of chain transfer agents can help control the molecular weight of the PVC by transferring the free radical from the growing polymer chain to another molecule, effectively terminating the chain and starting a new one.6. Polymerization method: The method of polymerization, such as suspension, emulsion, or bulk polymerization, can influence the properties of the final PVC product, including particle size, porosity, and molecular weight distribution.By carefully controlling these factors, chemists can tailor the properties of the final PVC product to meet specific requirements for various applications.