At present, plastics have developed to more than 300 kinds, and there are more than a dozen of the most commonly used plastics.
1. According to the application field of plastics, it is generally divided into general plastics and engineering plastics:
General plastics can only be used as general non-structural materials, their output is large, the price is relatively low, the performance is average, and it is mostly used to make daily necessities. (e.g. PE, PP, PVC, PS, PMMA, EVA, etc.)
Engineering plastics refer to high mechanical properties and high temperature resistance, corrosion resistance, can be used as structural materials, with excellent comprehensive properties (including: mechanical properties, electrical properties, heat resistance, chemical resistance, etc.), can maintain this performance well in a wide temperature range and a long time, and can be used for a long time in the withstand mechanical stress and more demanding chemical and physical environments. The seven major engineering plastics recognized are: ABS, PC, POM, PA, PET, PBT, PPO, PPO, etc., the output of engineering plastics is relatively small, and the price is more expensive. In addition, there are functional plastics (such as: LCP, artificial organs, etc.), nanoplastics, degradable plastics, etc.
2. Classification according to the crystalline form of plastics
It is generally divided into crystalline plastics and amorphous plastics
Crystalline plastics refer to plastics with a certain geometric structure (such as: PE, PP, PA, POM, PET, PBT, etc.) under appropriate conditions, most of which belong to the partial crystalline state. Amorphous plastics refer to plastics with molecular shapes and molecular arrangements that do not show crystal structure and are in a disordered state (such as: ABS, PC, PVC, PS, PMMA, EVA, AS, etc.), and amorphous plastics exhibit the same mechanical properties in all directions (isotropic).
3. Classified according to the basic behavior it presents when heated
It is generally divided into thermoplastics and thermosets
Thermoplastics refer to plastics that can be repeatedly heated and softened and cooled to harden in a specific temperature range (such as: ABS, PP, POM, PC, PS, PVC, PA, PMMA, etc.), which can be recycled. Thermosetting plastics refer to plastics that become non-melting substances after heating, and are no longer malleable when heated again and can no longer be recycled (such as: phenolic resin, epoxy resin, amino resin, polyurethane, expanded polystyrene, etc.).
4. Classification according to the light transmittance of plastics
It is generally divided into transparent plastics, translucent plastics and opaque plastics.
Plastics with light transmittance above 88% are called transparent plastics (such as: PMMA, PS, PC, Z-polyester, etc.), commonly used translucent plastics are: PP, PVC, PE,
AS, PET, MBS, PSF, etc., opaque plastics mainly include POM, PA, ABS, HIPS, PPO, etc.
5. Classified according to the hardness of plastics
It is generally divided into hard plastics, semi-rigid plastics, and soft plastics
Common rigid plastics are: ABS, POM, PS, PMMA, PC, PET, PBT, PPO, etc.;
Semi-rigid plastics are: PP, PE, PA, PVC, etc.;
Soft plastics are: soft PVC, K glue (BS), TPE, TPR, EVA, TPU, TPU, etc.
6. Classification according to the chemical structure of plastics
A. Polyolefins (such as: LDPE, MDPE, HDPE, LLDPE, UHMWPE, PP, etc.)
B. Polystyrene (such as: PS, AS, BS, ABS, MBS, HIPS, etc.) C. Polyamides (such as: PA6, PA66, PA610, PA1010, etc.) D. Polyethers (such as: PC, POM, PSF, PPO, PPO, etc.) · E, polyester (such as: PBT, PET, etc.) · F. Acrylates (e.g. PMMA)
