塑料的特性和作用（Characteristics and functions of plastics）.doc

塑料的特性和作用（Characteristics and functions of plastics） Plastic is a widely used synthetic polymer material, in our daily life, plastic products abound. We wake up from the use of toiletries, the breakfast dishes, to work with the rest of the stationery, with cushions, mattresses, and TV, washing machine, computer shell, and night gave us the light of the lamps in various shapes...... Plastics have gradually replaced many materials and utensils that have been used for decades and centuries with their excellent performance, becoming an indispensable assistant in peoples life. Plastic, metal in hard wood, light transparent glass ceramics, corrosion resistance, rubber elasticity and toughness in a body, in addition to daily necessities, plastic more widely used in aerospace, medical equipment, petroleum chemical industry, machinery manufacturing, defense, construction and other industries. I. classification of plastics There are many kinds of plastics. So far, there are about more than 300 kinds of plastic produced in the world. Plastic classification methods are more common, there are two kinds: 1, according to the nature of the plastic after heating, divided into thermoplastic and thermosetting plastics Thermoplastic structures are linear structures that soften or melt when heated and are plastically made into a definite shape and hardened after cooling. After heating to a certain extent, it softens again and hardens again after cooling. This process can be repeated many times. Such as PVC, polyethylene, polystyrene and so on. Thermoplastic molding process is relatively simple, can be continuous production, and has a high mechanical strength, so the development of very fast. The molecular structure of thermosetting plastics is the body structure, softening also occurs in heated, can plastic into a certain shape, but is heated to a certain extent or amount of curing agent, hardened stereotypes, re heating will not soften and change the shape of the. Thermosetting plastic