The synthesis of polyvinyl chloride PVC from vinyl chloride monomer VCM involves the following key steps:1. Initiation: The polymerization process begins with the addition of an initiator, which is typically a peroxide or an azo compound. The initiator breaks down into free radicals, which react with the vinyl chloride monomer to form a reactive intermediate.Optimization: The choice of initiator and its concentration can significantly affect the polymerization rate and the molecular weight of the resulting PVC. A suitable initiator should have a suitable decomposition temperature and generate free radicals at an appropriate rate. The initiator concentration should be optimized to balance the polymerization rate and the desired molecular weight.2. Propagation: The reactive intermediate reacts with another vinyl chloride monomer, forming a covalent bond and generating a new reactive intermediate. This process repeats itself, leading to the formation of a growing polymer chain.Optimization: The reaction temperature and pressure can be optimized to enhance the polymerization rate and control the molecular weight distribution. Higher temperatures and pressures generally lead to faster polymerization rates, but may also cause side reactions and degradation. The optimal conditions should be determined experimentally for each specific process.3. Termination: The polymerization process ends when two reactive intermediates react with each other, or when a reactive intermediate reacts with a chain transfer agent, which can be intentionally added to control the molecular weight.Optimization: The choice and concentration of chain transfer agents can be used to control the molecular weight and molecular weight distribution of the resulting PVC. The optimal chain transfer agent and its concentration should be determined based on the desired properties of the final PVC product.4. Post-polymerization treatments: After the polymerization is complete, the resulting PVC may be subjected to various treatments, such as dehydrochlorination, stabilization, and plasticization, to improve its properties and processability.Optimization: The choice of stabilizers, plasticizers, and other additives should be based on the desired properties of the final PVC product. The optimal concentrations and processing conditions for these additives should be determined experimentally.In summary, the key steps in the synthesis of PVC from VCM are initiation, propagation, termination, and post-polymerization treatments. Optimization of these steps can be achieved through the careful selection of initiators, chain transfer agents, reaction conditions, and additives, as well as the control of molecular weight and molecular weight distribution.