2.PVC is a very important process parameter during processing. If this parameter is improper, the problem of material decomposition will be caused. The flow characteristics of PVC are rather poor, and the process range is very narrow. In particular, the PVC material with large molecular weight is more difficult to be processed (this material is usually added to the lubricant to improve the flow characteristics), so it is usually used for small molecular weight PVC materials. The shrinkage rate of PVC is quite low, which is generally 0.2~0.6%.

2.PVC can be divided into hard PVC and soft PVC. Hard PVC accounts for about 2/3 of the market and soft PVC accounts for 1/3. Soft PVC is generally used in the surface of the floor, ceiling and leather, but because soft PVC contains softener (which is also the difference between soft PVC and hard PVC), it is easy to become brittle and not easy to preserve, so the scope of its use is limited. Hard PVC does not contain softeners, so it is flexible, easy to form, brittle, non-toxic, non polluting, and has long storage time. Therefore, it has great development and application value. Soft PVC is used to make vacuum plastic film, which is used for the surface packing of various panels. So it is also called decorative film and adhesive film. It is used in building materials, packaging, medicine and many other industries. The largest proportion of the building materials industry is 60%, followed by the packaging industry, as well as a number of other small sectors.

3.PVC is actually a vinyl polymerized material, which is a noncrystalline material. PVC materials are often added stabilizers, lubricants, auxiliary processing agents, pigments, impact resistant agents and other additives. It has no flammability, high strength, weather resistance and excellent geometric stability. PVC has strong resistance to oxidants, reducing agents and strong acids. However, it can be corroded by concentrated oxidizing acid such as concentrated sulfuric acid and concentrated nitric acid, and it is not suitable for the contact with aromatic hydrocarbon and chlorinated hydrocarbon.