1 PVC material has non flammability, high strength, weather resistance and excellent geometric stability.n2 PVC has strong resistance to oxidants, reducing agents and strong acids. However, it can be corroded by concentrated oxidizing acids, such as concentrated sulfuric acid and concentrated nitric acid, and it is not suitable for contact with aromatic hydrocarbons and chlorinated hydrocarbonsn3 The melting temperature of PVC during processing is a very important process parameter. If this parameter is improper, it will lead to the problem of material decomposition.n4 The flow characteristics of PVC are quite poor, and its process range is very narrow. In particular, PVC materials with large molecular weight are more difficult to process (such materials usually need to add lubricant to improve flow characteristics), so PVC materials with small molecular weight are usually used.n5 The shrinkage of PVC is quite low, generally 0.2~0.6%.