欧美丝袜自拍_亚洲国产九九_小小影视电影_91超碰一区二区三区_菠萝菠萝蜜视频_国产精品视频网址!_欧美成人免费全部色播_99久久无码囯产精品_亚洲h片在线观看高清_日本不卡的在线播放

Plastic products are the collective name for life, industry and other products that are processed from plastic as the main raw material. Including plastics as raw materials for injection molding, plastic molding and other processes of products. Plastic is a kind of synthetic polymer material with plasticity.
It forms three major synthetic materials that are indispensable for daily life with synthetic rubber and synthetic fibers. Specifically, the plastic is a material which is made of a natural or synthetic resin as a main component, is added with various additives, can be molded into a certain shape under a certain temperature and pressure, and maintains a shape at a normal temperature.
Compared with other materials, plastic has the following performance characteristics:
1. Light weight
Plastics are lighter materials with a relative density between 0.90 and 2.2. Obviously, can plastics float to the surface? In particular, foamed plastics have a lighter texture and a lighter density with a relative density of only 0.01. This property allows plastics to be used in the production of products that require a reduction in their own weight.
2. Excellent chemical stability
Most plastics have good corrosion resistance to acids, alkalis and other chemicals. Especially known as the plastic king of PTFE (F4), its chemical stability is even better than gold, put in "Aqua regia" boiled for more than ten hours will not deteriorate. Due to its excellent chemical stability, F4 is an ideal corrosion resistant material. For example, F4 can be used as a material for conveying corrosive and viscous liquid pipes.
3. Excellent electrical insulation properties
Ordinary plastics are poor conductors of electricity, and their surface resistance and volume resistance are very large, which can be represented by numbers to 109 to 1018 ohms. The breakdown voltage is large and the dielectric loss tangent is small. Therefore, plastics have a wide range of applications in the electronics and machinery industries. Such as plastic insulated control cables.
4. Poor conductor of heat, with noise reduction and shock absorption
In general, the thermal conductivity of plastics is relatively low, equivalent to 1/75 to 1/25 of steel, the micropores of foam.
It contains gas, which is better in heat insulation, sound insulation and shock resistance. For example, the thermal conductivity of polyvinyl chloride (PVC) is only 1/357 of that of steel and 1/1250 of aluminum. In terms of heat insulation capacity, the single glass plastic window is 40% higher than the single glass aluminum window, and the double glass is 50% higher. After combining the plastic form with the insulating glass, it is used in residential buildings, office buildings, wards, hotels, saving heating in winter and saving air conditioning costs in summer. The benefits are obvious.
5. Wide mechanical strength distribution and high specific strength
Some plastics are as hard as stones, steel, and some are soft like paper and leather. From the mechanical properties of hardness, tensile strength, elongation and impact strength of plastics, the distribution range is wide, and there is a great choice for use. Because of its small specific gravity and high strength, plastics have a high specific strength. Compared with other materials, plastics also have obvious disadvantages, such as easy burning, low rigidity, poor aging resistance, and heat resistance.