Plastic bottle manufacturers tell you that there are many kinds of plastics. To date, there are more than 300 types of plastic put into production. There are many ways to classify plastic bottles into two categories:

　　1. Plastic bottle manufacturers are divided into thermoplastic and thermosetting plastics according to the different properties of plastic bottles when subjected to heat

　　The molecular structure of thermoplastic plastic is linear. When heated, it softens or melts. It can be moulded into relative shapes and then hardened after cooling. After several coolings, it can be softened by heating again. Examples include polyvinyl chloride, polyethylene and polystyrene. Thermoplastics are relatively simple to mould, can be produced continuously and have a high mechanical strength, hence the speed of development.

　　The molecular structure of thermosetting plastics is intrinsically structured, which softens when heated and can be trimmed to shape. However, when heated to the appropriate degree or when a small amount of curing agent is added, it hardens and solidifies and does not soften and change shape when heated again. Thermoset plastics, such as phenolic, amino and epoxy resins, cannot be recycled because they do not soften when heated. Thermosetting plastics are complex to mould and have relative difficulties in continuous production, but they are heat resistant, not easily deformed and relatively inexpensive.

　　2. Plastic bottle manufacturers are divided into general plastics and engineering plastics according to the different uses of plastic bottles.

　　General plastics are plastics with large production volume, low price and relatively wide range of applications, mainly including polyolefins, polyvinyl chloride, polystyrene, phenolic plastics, amino plastics, etc. Many products that people use in their daily lives are made from these general purpose plastics.

　　Engineering plastics can be used as engineering structural materials to manufacture mechanical parts instead of metal. Such as polyamide, polycarbonate, polyformaldehyde, ABS resin, polytetrafluoroethylene, polyester, polysulfone, polyimide, etc.. Engineering plastics have low density, high chemical properties, good mechanical properties, good electrical insulation properties, easy processing and other characteristics. They are used in a variety of industries such as automobiles, electrical appliances, chemicals, machinery, instruments and meters, as well as aerospace navigation, rockets and missiles.