Common classification methods for plastics

There are many kinds of plastics , so far there are about 300 kinds of plastics put into production in the world. There are many ways to classify plastics. There are two commonly used methods:  

Engineering plastics are plastics that can be used as engineering structural materials and substitute metal manufacturing machine parts. For example, polyamide, polycarbonate, polyoxymethylene, ABS resin, polytetrafluoroethylene, polyester, polysulfone, polyimide, and the like. Engineering plastics with low density, high chemical stability, good mechanical properties, excellent electrical insulation, easy molding processing characteristics, widely used in automotive, electronics, chemicals, machinery, instruments, meters and other industries, also used in space travel, rocket And missiles. GE Plastics refers yield, low cost, wide range of applications of plastics, including polyolefins, polyvinyl chloride, polystyrene, phenolics and aminoplasts five varieties. Many of the products used in people's daily lives are made from these common plastics .   , Depending on the use of plastic divided into general-purpose plastics and engineering plastics   The molecular structure of thermosetting plastics is a bulk structure, which also softens when heated, and can be molded into a certain shape, but when it is heated to a certain degree or a small amount of a curing agent is added, it is hardened and set, and heating does not become soft and change. Shaped. After the thermosetting plastics molding process, the heat will not soften, and therefore can not be recovered for reuse, such as phenolics, aminoplasts, epoxy plastics belong to this category. Thermosetting plastic molding process is more complicated, so there is a certain difficulty in continuous production, but its heat resistance is good, not easily deformed, and the price is relatively low.         Thermoplastic molecular structures are linear structures that soften or melt when heated, can be molded into certain shapes, and harden after cooling. It heats up to a certain degree and then re-softens, hardens after cooling, and this process can be repeated many times. Such as polyvinyl chloride, polyethylene, polystyrene and so on. Thermoplastic molding process is relatively simple, continuous production is possible, and having a relatively high mechanical strength, and therefore developed rapidly.   Depending on the nature of the plastic after heating, it can be divided into thermoplastics and thermosetting plastics.