olyethylene, the smaller the index is, the larger the molecular weight and the higher the mechanical strength, although the fluidity is lower The low heat resistance and the inactive chemical property of polyethylene result in bad nd bondin The substance can be used to manufacture all kinds of bottles, fishnet, ropes, cables, telephone wire stringing, chopping boards as well as dustbins etc 6. Polypropylene(PP) Polypropylene is closely connected with polyethylene with respect to raw materials, manufacturing technique as well as properties. The raw materials, i. e. propylene and ethylene, are both contained in a large amount in the decomposing gas of petroleum. Above all, polypropylene and polyethylene are manufactured with the same industrial method, namely, through polymerization with catalyzer under low pressure. Polypropylene is an equilibrious polymer, with regular molecular structure and orderly arrangement, and which is provided with high crystallinity and superior heat resistance and intensity. Its relative density is 0.90-0.92 and thus is the lightest plastic. It can burn like polyethylene after being ignited, with rather stinky smoke, which can be differentiated from polyethylene. The softening point of polypropylene, far higher than polyethylene of high density, can reach 170C. It is of sound transparency and high tensile resistance and surface hardness Polypropylene is of low impact resistance under low temperature Foodstuff containers made of such substance can crack easily if falling off during their being taken in or out of the refrigerator. moreover, it cannot resist against ultraviolet radiation Polypropylene can be used to make shells of electric appliances, water buckets, foodstuff containers, pipes and tubes, filter cloth, fishnet and ropes etc 7. Flurocarbon Resins Flurocarbon resin is a kind of engineering plastic with excellent performance. Its chemical sistance and electric insulation is the best among plastics and its property will not change whether under high temperature or low temperature. The price, however, is a bit too high Flurocarbon resin contains various types of polymers, though in industry only four types are available: quadri-fluorinated-resin, tri-fluorinated-resin, polyvinylidene fluoride and FEP resin. It is basically made through the polymerization of dichlorodifluoro-methane monomer. The advantage of Flurocarbon resin over other plastics is that it is against erosion from chemicals and is sound in such electric properties as heat resistance and high frequency resistance. Quadri-fluorinated-resin, tri-fluorinated-resin and polyvinylidene fluoride are stable respectively ithin the range of-200℃-250℃,-200℃~250℃and-60℃-150℃. Since it does not absorb moisture. the substance can serve as the ideal electric insulation or anti-erosion material. It can be improved in performance and can be miniaturized respect to the field of wireless communication equipment such as electric instruments, radars, televisions as well as microwave relay devices etc. Polyvinylidene fluoride can fight against ultraviolet radiation and its performance remains unchanged all the year round. Endowed with such attributes, it can be applied in building material 8. Polyamide Resins(Nylon, PA)polyethylene; the smaller the index is, the larger the molecular weight and the higher the mechanical strength, although the fluidity is lower. The low heat resistance and the inactive chemical property of polyethylene result in bad printing and bonding. The substance can be used to manufacture all kinds of bottles, fishnet, ropes, cables, telephone wire stringing, chopping boards as well as dustbins etc. 6. Polypropylene (PP) Polypropylene is closely connected with polyethylene with respect to raw materials, manufacturing technique as well as properties. The raw materials, i.e. propylene and ethylene, are both contained in a large amount in the decomposing gas of petroleum. Above all, polypropylene and polyethylene are manufactured with the same industrial method, namely, through polymerization with catalyzer under low pressure. Polypropylene is an equilibrious polymer, with regular molecular structure and orderly arrangement, and which is provided with high crystallinity and superior heat resistance and intensity. Its relative density is 0.90~0.92 and thus is the lightest plastic. It can burn like polyethylene after being ignited, with rather stinky smoke, which can be differentiated from polyethylene. The softening point of polypropylene, far higher than polyethylene of high density, can reach 170 . It ℃ is of sound transparency and high tensile resistance and surface hardness. Polypropylene is of low impact resistance under low temperature. Foodstuff containers made of such substance can crack easily if falling off during their being taken in or out of the refrigerator. Moreover, it cannot resist against ultraviolet radiation. Polypropylene can be used to make shells of electric appliances, water buckets, foodstuff containers, pipes and tubes, filter cloth, fishnet and ropes etc. 7. Flurocarbon Resins Flurocarbon resin is a kind of engineering plastic with excellent performance. Its chemical resistance and electric insulation is the best among plastics and its property will not change whether under high temperature or low temperature. The price, however, is a bit too high. Flurocarbon resin contains various types of polymers, though in industry only four types are available: quadri-fluorinated-resin, tri-fluorinated-resin, polyvinylidene fluoride and FEP resin. It is basically made through the polymerization of dichlorodifluoro-methane monomer. The advantage of Flurocarbon resin over other plastics is that it is against erosion from chemicals and is sound in such electric properties as heat resistance and high frequency resistance. Quadri-fluorinated-resin, tri-fluorinated-resin and polyvinylidene fluoride are stable respectively within the range of -200℃~250 , ℃ -200℃~250 and ℃ -60℃~150℃. Since it does not absorb moisture, the substance can serve as the ideal electric insulation or anti-erosion material. It can be improved in performance and can be miniaturized with respect to the field of wireless communication equipment such as electric instruments, radars, televisions as well as microwave relay devices etc. Polyvinylidene fluoride can fight against ultraviolet radiation and its performance remains unchanged all the year round. Endowed with such attributes, it can be applied in building materials. 8. Polyamide Resins (Nylon, PA)