Nylons are generally tough and strong and boast high oil resistance and chemical resistance They can be in stable use whether under high temperature or low temperature and hence possess excellent qualification for being used as engineering plastics. The friction coefficient of nylons is small, which indicates that it is high in abrasion resistance. Their friction coefficient against steel is 0. 15, whereas that of polyamide against polyamide is 0. 1. Therefore, nylons or polyamide resins are specially used to manufacture mechanical parts and pulleys such as the small gears, cam and axletrees of recorders, duplicating machines as well as computers. Nylons can absorb moistures easily, whereby their dimension and strength will change with the absorption. Hence, special attention should be paid when it requires high precision and the materials must be fully dried during molding The substance can be used to make such products as gears, connector of electric appliances, lamp shells, engine fan blades, mirrors, crusts, electronic parts, axletrees, computers, TV modules, roller skates soles, ball cases, zippers, fishing threads, brush hair, combs, high pressure tubes and 9. Acetal Resins(POM) POM is a tough and strong material with sound heat resistance and solvent resistance. The property of POM is similar to nylon and PC, which is pretty strong and requires high thermal deformation temperature. In addition, the substance is superior in abrasion resistance and will not easily get deformed even under long-time loading. Moreover, its property hardly changes after repeated bending, and thus it is also called plastic spring. Its low friction coefficient against steel almost equals that of nylon and its dimension change attributed to moisture absorption is also far ower than that of nylon camera parts, internal parts of clocks and watches, zippers as well as computer parts ef os, cams, The substance can be used to make vehicle parts, gears, electronic parts, water ta 10. Polycarbonate Resin(PC) PC is a kind of colorless or primrose material, with high tensile strength, bending intensity, elasticity and impact resistance. These physical properties, almost equal to metallic materials, will not change dramatically with different temperature and the intensity can be retained under 140C Its brittle temperature is as low as-100C-140C and the impact resistance is pretty high mounting to the top among plastics. It can be made into rubber helmets and safety helmets. It is also provided with strong resistance against ultraviolet radiation; a weather resistance test wherein the substance is exposed outdoors for ten years proves that its mechanical property remains tota unchanged. In addition, it is sound in electric property. The chemical resistance is against acid rather than alkali. Only when temperature reaches 220 C-230C will PC begin to be softened and fused. Due to its high viscosity, the substance, during molding and processing, requires high temperature and pressure higher than that of polystyrene or propylene resins PC can be manufactured into safety helmets, various mechanical parts and shells as well as components of electric mechanic appliances which require high electric insulation, intensity, heat resistance, transparency, vibration endurance and stable dimension. 11. Cellulose plastics The cellulose plastic is provided with high transparency and pliability as well as soundNylons are generally tough and strong and boast high oil resistance and chemical resistance. They can be in stable use whether under high temperature or low temperature and hence possess excellent qualification for being used as engineering plastics. The friction coefficient of nylons is small, which indicates that it is high in abrasion resistance. Their friction coefficient against steel is 0.15, whereas that of polyamide against polyamide is 0.1. Therefore, nylons or polyamide resins are specially used to manufacture mechanical parts and pulleys such as the small gears, cam and axletrees of recorders, duplicating machines as well as computers. Nylons can absorb moistures easily, whereby their dimension and strength will change with the absorption. Hence, special attention should be paid when it requires high precision and the materials must be fully dried during molding. The substance can be used to make such products as gears, connector of electric appliances, lamp shells, engine fan blades, mirrors, crusts, electronic parts, axletrees, computers, TV modules, roller skates soles, ball cases, zippers, fishing threads, brush hair, combs, high pressure tubes and gunstock etc. 9. Acetal Resins (POM) POM is a tough and strong material with sound heat resistance and solvent resistance. The property of POM is similar to nylon and PC, which is pretty strong and requires high thermal deformation temperature. In addition, the substance is superior in abrasion resistance and will not easily get deformed even under long-time loading. Moreover, its property hardly changes after repeated bending, and thus it is also called plastic spring. Its low friction coefficient against steel almost equals that of nylon and its dimension change attributed to moisture absorption is also far lower than that of nylon. The substance can be used to make vehicle parts, gears, electronic parts, water taps, cams, camera parts, internal parts of clocks and watches, zippers as well as computer parts etc. 10. Polycarbonate Resin (PC) PC is a kind of colorless or primrose material, with high tensile strength, bending intensity, elasticity and impact resistance. These physical properties, almost equal to metallic materials, will not change dramatically with different temperature and the intensity can be retained under 140 . ℃ Its brittle temperature is as low as -100℃~140℃ and the impact resistance is pretty high, amounting to the top among plastics. It can be made into rubber helmets and safety helmets. It is also provided with strong resistance against ultraviolet radiation; a weather resistance test wherein the substance is exposed outdoors for ten years proves that its mechanical property remains totally unchanged. In addition, it is sound in electric property. The chemical resistance is against acid rather than alkali. Only when temperature reaches 220℃~230℃ will PC begin to be softened and fused. Due to its high viscosity, the substance, during molding and processing, requires high temperature and pressure higher than that of polystyrene or propylene resins. PC can be manufactured into safety helmets, various mechanical parts and shells as well as components of electric mechanic appliances which require high electric insulation, intensity, heat resistance, transparency, vibration endurance and stable dimension. 11. Cellulose Plastics The cellulose plastic is provided with high transparency and pliability as well as sound