There are hundreds of plastics produced in industry, of which more than 60 are commonly used. The common classification methods are as follows:
According to the performance after heating
1. Thermosetting plastics
The characteristic of this kind of plastic is that it can be cured at a certain temperature after a certain time of heating or adding a curing agent.
The cured plastic is hard and insoluble in any solvent and cannot be softened again by heating. If the heating temperature is too high, it will decompose. Common thermosetting plastics include bakelite, electrical jade, decorative board and unsaturated polyester plastic.
This kind of plastic is characterized by softening by heating, hardening by cooling, and only physical changes in the processing process to maintain its chemical nature. Most of the resins of this kind of plastics are made by addition polymerization. Common thermoplastics include: nitrocellulose plastics, acetate plastics, polyethylene plastics, polypropylene plastics, polystyrene plastics, PVC plastics, etc. For example, our common mineral water bottles, plastic bags, etc.
By application scope
1. General plastics
This kind of plastic mainly refers to a kind of plastic with large output, wide use and low price. They account for about 80% of the total plastic output. The main varieties are: polyethylene, PVC, polypropylene, polystyrene, phenolic and amino plastics, etc.
2. Engineering plastics
Generally, it refers to the plastics that can be used as structural materials in engineering technology. This kind of plastic is characterized by high mechanical strength, chemical corrosion resistance and high temperature resistance. It can replace metal or be used for other special purposes. The main varieties are: polyamide, polycarbonate, POM, polysulfone, ABS, polyphenylene ether, fluoroplastics, etc.
1. Flammable plastic
This kind of plastic burns violently after encountering open fire and is not easy to extinguish. Such as nitrocellulose plastics, which are classified as dangerous goods.
2. Combustible plastics
This kind of plastic burns with open fire, without self extinguishing property, but the burning speed is faster. Such as polyethylene, polypropylene, etc.
3. Flame retardant plastic
This kind of plastic can burn in a strong open fire, and will soon go out after leaving the fire. Such as phenolic plastics, acetate plastics, PVC plastics, etc.