Polyethylene is odorless and non-toxic, feels like wax, and has excellent low temperature resistance (the lowest service temperature can reach-100 ~-70℃), good chemical stability and resistance to most acids and bases (not oxidative acids). Insoluble in general solvents at room temperature, low water absorption and excellent electrical insulation.
Extended data:
I. Identification
Polyethylene material is difficult to print (unless it is modified by body or surface), so it is mostly colorless or light-colored products. Of course, due to its good environmental aging resistance, polyethylene is mostly used in artificial turf on sports grounds.
The simplest identification method is to ignite a small sample with a gas flame (such as a lighter). The sample will continue to burn, smelling of smoke and candles. Scrape it with your nails. What is scratched is low density polyethylene (LDPE), otherwise it is high density polyethylene (HDPE).
Second, the related nature
1, polyethylene has excellent chemical stability and can resist the corrosion of hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid, amines, sodium hydroxide, potassium hydroxide and other chemicals at room temperature, but nitric acid and sulfuric acid have strong destructive effects on polyethylene;
2. Polyethylene is prone to photooxidation, thermal oxidation and ozone decomposition, and is easily degraded under the action of ultraviolet rays. Carbon black has a good shading effect on polyethylene. After irradiation, crosslinking, chain breakage and the formation of unsaturated groups will occur.
An opalescent translucent thermoplastic is made of ethylene homopolymerization and a small amount of α -olefin polymerization. The density is 0.86-0.96g/cm3. According to density, there are low density polyethylene (including linear low density polyethylene) and ultra-low density polyethylene.
Odorless and nontoxic. Resistant to chemicals, insoluble in solvents at room temperature. Low-temperature resistance, the lowest use temperature is -70 ~- 100℃. Good electrical insulation and low water absorption. Physical and mechanical properties vary with density. Industrial low-density polyethylene mainly adopts high-pressure (1 10 ~ 200mpa) and high-temperature (150 ~ 300℃) free radical polymerization.
Others use low-pressure coordination polymerization, and sometimes the same set of equipment can produce polyethylene products with density of 0.87 ~ 0.96 g/cm3, which is called full-density polyethylene process technology. Polyethylene can be processed into films, wire and cable sheaths, pipes, various hollow products, injection molded products, fibers and so on. Widely used in agriculture, packaging, electronics, machinery, automobiles, daily necessities and so on.
Baidu encyclopedia-polyethylene