①Most plastics are light in weight, chemically stable, and will not rust; ②Good impact resistance; ③Good transparency and wear resistance; ④Good insulation, low thermal conductivity; ⑤General formability and colorability Good, low processing cost; ⑥Most plastics have poor heat resistance, high thermal expansion rate and easy to burn; ⑦Poor dimensional stability, easy to deform; ⑧Most plastics have poor low temperature resistance and become brittle at low temperatures; ⑨Easy to age; ⑩Some plastics are easy to aging; Soluble in solvents. Plastics can be divided into two types: thermosetting and thermoplastic. The former cannot be reshaped and used, and the latter can be repeatedly produced.
There are basically two types of plastic polymer structures: the first is a linear structure, and a polymer compound with this structure is called a linear polymer compound; the second is a body structure, which has The polymer compound of this structure is called a bulk polymer compound. Some macromolecules are branched, called branched macromolecules, which belong to the linear structure. Although some polymers have cross-links between molecules, they are less cross-linked, which is called a network structure and belongs to a body structure. Two different structures show two opposite properties. Linear structure (including branched structure) polymers are elastic and plastic due to the existence of independent molecules, can be dissolved in solvents, can be melted by heating, and have low hardness and brittleness. Because there are no independent macromolecules in the body structure polymer, it has no elasticity and plasticity, cannot dissolve and melt, can only swell, and has greater hardness and brittleness. Plastics have two types of macromolecules. Those made of linear polymers are thermoplastics, and those made of body-shaped polymers are thermoset plastics.