Plastic, that is, plastic rubber, is a rubber granule formed by the polymerization of petroleum refining products and certain chemical elements. It is processed by manufacturers to form plastic products of various shapes.
1. Classification of plastics: After processing and heating, plastics can be divided into two categories: thermoplastic and thermosetting. Common are the following:
1) PVC—polyvinyl chloride
2) PE—polyethylene, HDPE—high density polyethylene, LDPE—low density polyethylene
3) PP—Polypropylene
4) PS—polystyrene
5) Other common printing materials are PC, PT, PET, EVA, PU, KOP, Tedolon, etc.
2. Simple identification method of various types of plastics:
Distinguish according to appearance:
1) PVC tape is soft and has very good extensibility. In addition, there are also some hard or foamed materials, such as water pipes, sliding doors, etc.
2) PS, ABS, soft and brittle texture, usually surface injection molding.
3) HDPE in PE is light in texture, good in toughness and opaque, while LDPE is slightly ductile.
4) PP has a certain transparency and is brittle.
Distinguish according to chemical properties:
1) PS, PC and ABS can be dissolved in toluene to corrode their surfaces.
2) PVC is insoluble with benzene, but can be dissolved with ketone solvent.
3) PP and PE have good alkali resistance and excellent solvent resistance.
Distinguish according to flammability:
1) When PVC is burned with fire, it will decompose the odor of chlorine, and once the fire leaves, it will not burn.
2) PE will produce a waxy smell when burning, with waxy droplets, but PP will not, and both will continue to burn after leaving the fire.
3. Characteristics of various plastics
1) Characteristics of PP: Although PP has transparency, its texture is easy to break, which is better for food packaging. A variety of different products can be derived by improving their fracture defects. For example: OPP and PP are uniaxially extended to improve their strength, which are commonly used in the outer packaging of paper towels and chopsticks.
2) Characteristics of PE: PE is made of ethylene. The density of LDPE is about 0.910 g/cm-0.940 g/cm. Because of its excellent toughness and moisture-proof ability, it is often used in food packaging, cosmetic packaging, etc. ; The density of HDPE is about 0.941 g/cm or more. Because of its light texture and heat resistance, it is often used in handbags and various convenience bags.
Post time: Sep-17-2022