PTA is one of the isomers of terephthalic acid. There are two carboxyl groups in the para position of benzene ring, and the chemical formula is p-C6H4(COOH)2. Terephthalic acid is a raw material for producing polyester, especially polyethylene terephthalate (PET). Linear low density polyethylene (LLDPE) is considered as a new variety of "the third generation polyethylene". Compared with ordinary low density polyethylene, linear low density polyethylene has lower energy consumption and higher output. In particular, its physical and chemical properties are much better than ordinary low density polyethylene, and it is widely used. PVC is actually a vinyl polymer, and its material is an amorphous material. In practical use, stabilizers, lubricants, processing AIDS, pigments, impact agents and other additives are often added to PVC materials. It is nonflammable, high strength, weatherability and excellent geometric stability. PVC has strong resistance to oxidants, reductants and strong acids. However, it can be corroded by concentrated oxidizing acids such as concentrated sulfuric acid and concentrated nitric acid, and is not suitable for contact with aromatic hydrocarbons and chlorinated hydrocarbons. In addition, the word "people vs computers" in the game is abbreviated as PVC, and PVC figures are often abbreviated as futures prices such as PVC: /futures/