Polyethylene terephthalate (PET)
Polyethylene terephthalate is a colorless transparent substance (unqualified) or an opaque milky white substance (crystalline type). It is difficult to burn on fire, but once burned, although the flame is away from it, it can continue to burn. When it burns, it will melt and burst into pieces. The flame is yellow, the edges are blue, and droplets fall, black smoke, and mountains. With a slightly sweet, pungent odor. The performance of pure PET is very poor, especially the impact strength and heat resistance are exceptional, but after being reinforced by glass fiber, various properties are greatly improved.
Physical properties: Polyethylene is non-toxic, tasteless and milky white. The density is from 0.91 to 0.96 g/cm3, which is a crystalline plastic. Polyethylene has a certain mechanical strength, but its mechanical strength is low compared to other plastics, and the surface hardness is poor.
Polyethylene has excellent insulating properties. At room temperature, polyethylene is insoluble in any known solvent, and is resistant to dilute sulfuric acid, dilute nitric acid and other acids of any concentration, as well as various concentrations of alkali and salt solutions. Polyethylene has a high degree of water resistance and its properties remain unchanged with long-term exposure to water. Polyethylene permeable gas has poor performance, while oxygen and carbon dioxide, as well as many organic matter vapors, perform well.
Use temperature - weather resistance: Polyethylene will cause aging and embrittlement under the action of heat, light and oxygen. Generally, the use temperature of high-pressure polyethylene is about 800C, and the low-pressure polyethylene is about 1000C. Polyethylene is cold resistant and still has good mechanical properties at -600C. It still has some softness at -700C.