Polyvinyl chloride PVC is synthesized from vinyl chloride monomer VCM through a process called free radical polymerization. Here is the step-by-step mechanism for the synthesis of PVC, including the role of initiator, temperature, and pressure in the reaction:1. Initiation: The first step in the polymerization process is the initiation, which involves the formation of free radicals. An initiator, such as benzoyl peroxide or azobisisobutyronitrile AIBN , is added to the reaction mixture. The initiator decomposes upon heating, generating free radicals. The temperature for this process is typically around 40-60C.2. Propagation: The free radicals generated in the initiation step react with the vinyl chloride monomer, forming a new radical species. This new radical species can then react with another vinyl chloride monomer, creating a longer chain radical. This process continues, with the chain growing in length as more and more monomers are added. The pressure for this process is typically around 5-20 atmospheres to ensure a high concentration of monomers in the reaction mixture, promoting the formation of long polymer chains.3. Chain transfer: During the propagation step, the growing polymer chain may react with another molecule, such as an impurity or solvent, transferring the radical to that molecule. This process terminates the growth of the original polymer chain and may initiate the growth of a new chain. Chain transfer reactions can affect the overall molecular weight and polydispersity of the resulting polymer.4. Termination: The polymerization process eventually comes to an end when two growing polymer chains or a growing chain and a free radical react with each other, forming a covalent bond and terminating the radical species. This results in the formation of the final PVC polymer.5. Post-polymerization processing: After the polymerization is complete, the PVC polymer is typically isolated by precipitation, filtration, or other separation techniques. The polymer may then be further processed, such as by adding plasticizers, stabilizers, or other additives, to achieve the desired properties for specific applications.In summary, the synthesis of polyvinyl chloride from vinyl chloride monomer involves a free radical polymerization process, with the initiator playing a crucial role in generating the free radicals needed for the reaction. Temperature and pressure are also important factors, as they influence the rate of initiator decomposition, monomer concentration, and overall polymerization kinetics.