1. Rigid PVC is one of the most widely used plastic materials.
　　 2. 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. The flow characteristics of PVC are quite poor and the process range is narrow. In particular, large molecular weight PVC materials are more difficult to process (this material usually incorporates a lubricant to improve flow characteristics), so small molecular weight PVC materials are commonly used. The shrinkage rate of PVC is quite low, generally 0.2 to 0.6%.
　　 3. 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 for the surface of floors, ceilings and leather, but because soft PVC contains softener (this is also the difference between soft PVC and hard PVC), it is easy to become brittle and difficult to store, so its scope of use has been limited. Hard PVC does not contain softener, so it has good flexibility, easy to form, is not brittle, non-toxic and non-polluting, and has a long storage time, so it has great development and application value. Soft PVC is mostly used to make vacuum plastic film, which is used for surface packaging of various panels. Therefore, it is also called decorative film and adhesive film. It is used in many industries such as building materials, packaging, medicine and so on. Among them, the building materials industry accounted for the largest proportion, 60%, followed by the packaging industry, and several other small-scale applications.
　　 4, PVC is actually a vinyl polymer, the material is a non-crystalline material. In practical use, PVC materials are often added with stabilizers, lubricants, auxiliary processing agents, colorants, impact agents and other additives. It has non-flammability, high strength, weather resistance and excellent geometric stability. PVC is highly resistant to oxidizing agents, reducing agents and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid, concentrated nitric acid, and is also not suitable for contact with aromatic hydrocarbons or chlorinated hydrocarbons.