Polyethylene terephthalate (PET)
Polyethylene terephthalate is a colorless, transparent substance with a slight sheen (amorphous), or an opaque, milky white substance (crystalline). It is difficult to ignite and burn, but once it does, it can continue to burn even after the flame is removed. It melts and explodes into fragments during combustion. The flame is yellow with a blue edge, with small droplets falling. It emits black smoke and has a slightly sweet, pungent odor. Pure PET has very poor properties, especially impact strength and heat resistance. However, after being reinforced with glass fiber, various properties are greatly improved.
Physical Properties: Polyethylene is non-toxic, odorless, and milky white. It is a crystalline plastic with a density of 0.91-0.96 g/cm³. Polyethylene has a certain degree of mechanical strength, but it is lower than other plastics and has a poorer surface hardness.
Polyethylene has excellent insulating properties. At room temperature, polyethylene is insoluble in all known solvents and is resistant to dilute sulfuric acid, dilute nitric acid, and other acids of all concentrations, as well as alkali and salt solutions of various concentrations. Polyethylene is highly water-resistant and maintains its properties even after long-term contact with water. Polyethylene has poor water vapor permeability but good permeability to oxygen, carbon dioxide, and the vapors of many organic substances.
Using Temperature – Weather Resistance: Polyethylene ages and becomes brittle under the influence of heat, light, and oxygen. The typical operating temperature for high-pressure polyethylene is around 800°C, while for low-pressure polyethylene it is around 1000°C. Polyethylene is also cold-resistant, maintaining good mechanical properties at -600°C and retaining a certain degree of flexibility at -700°C.
Post time: Aug-12-2025