The optimum reaction temperature for the synthesis of polyvinyl chloride PVC from vinyl chloride monomer VCM is typically in the range of 40-60C. This temperature range is chosen to balance the reaction rate, yield, and properties of the final PVC product.At lower temperatures, the reaction rate is slower, which can lead to lower yields and longer reaction times. However, lower temperatures can also result in PVC with a higher molecular weight, which can improve its mechanical properties, such as tensile strength and impact resistance.At higher temperatures, the reaction rate is faster, which can lead to higher yields and shorter reaction times. However, higher temperatures can also result in PVC with a lower molecular weight, which can negatively affect its mechanical properties. Additionally, higher temperatures can increase the risk of side reactions and degradation of the PVC, leading to discoloration and reduced product quality.In summary, the optimum reaction temperature for PVC synthesis is a balance between reaction rate, yield, and product properties. The temperature range of 40-60C is generally considered optimal for achieving a good balance between these factors.