plastic flakes

It is necessary for those who do plastic recycling to understand the classification of plastics and the properties of various plastics. Today, we will introduce you to some general knowledge about plastics.

Classification by application area

  • General-purpose plastics: can only be used as non-structural materials, large production volume, relatively low price. But the performance is general, many manufacturers.
  • Engineering plastics: can be used as structural materials, with excellent mechanical properties, electrical properties, heat resistance, chemical resistance, dimensional stability, and processing performance.
  • Can be divided into general engineering plastics and special engineering plastics. The latter has higher performance, smaller production, fewer manufacturers, and higher sales prices.

By physical and chemical properties of plastics

Thermoplastics: Plastics that generally have only physical volume changes during processing. That is, plastics that can be repeatedly heated, softened, and cooled to harden within a specific temperature range. (Common: PVC, polyethylene, polypropylene, polystyrene, ABS, SAN, nylon, polyformaldehyde, polycarbonate, polyphenylene ether, polymethacrylate, polyurethane, polyethylene terephthalate)

Thermoset plastics: chemical changes occur during processing. When heated, they begin to soften and become somewhat plastic. However, with further heating, the resin hardens and molds. If reheated, they generally cannot be remolded and can only be crushed for use.

plastic bags

Crystalline and non-crystalline plastics

Crystalline plastics have a distinct melting point and regular arrangement of molecules when solid. Regularly arranged regions are called crystalline regions, and disordered regions are called amorphous regions. The percentage of crystalline regions is called the degree of crystallinity. The percentage of crystalline regions is called the degree of crystallinity. Generally, polymers with a degree of crystallinity greater than 80% are called crystalline plastics.

  • Crystalline plastics: PA, PP, PE, POM, PBT, PET, PPO
  • Amorphous plastics: PC, ABS, PS, PVC, PMMA
pp plastic scrap

Shuliy has extensive experience in the field of plastic recycling. We have plastic shredders, plastic granulators previously other plastic recycling machines for sale. To know more about plastic recycling, please feel free to leave a message on our website.