了解最新久免费视频_国产精品美女网站_使劲快喷了高潮了视频_影音新男人AV资源网站_91人妻中文字幕在线精品_久久天天躁狠狠躁夜夜202_国产在线观看自拍_中文字幕自拍制服丝袜_草莓视频深夜福利_在线黄色片2019年理论黄色三级片

Plastic products are widely used, and huge downstream occupations provide strong support for the development of plastic products in China. Following the promulgation of the “Revitalization of Petrochemical Career Planning Rules”, China's plastic products industry has ushered in new opportunities for development. China's plastic products market demand is mainly concentrated in agricultural plastic products, packaging plastic products, construction of plastic products, industrial transportation and engineering plastic products.

  1. Light weight

Plastics are lighter materials with a relative density between 0.90 and 2.2. Obviously, can plastic float to the surface? In particular, foamed plastics have a lighter texture and a lighter 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 the ideal corrosion resistance material. For example, F4 can be used as a means of transporting corrosive and viscous liquid pipes.

3. Excellent electrical insulation function

Generally, plastics are poor conductors of electricity, and their surface resistance and volume resistance are very large, and can be represented by numbers to 109 to 1018 ohms. The breakdown voltage is large and the dielectric loss tangent is small. Thus, 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 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 can be used in residences, office buildings, wards, hotels, saves heat in winter, and saves air-conditioning expenses in summer. The advantages are very significant.

5. Wide mechanical strength distribution and high specific strength

Some plastics are as strong as stones, steel, and some are soft like paper and leather. From the mechanical properties of plastics such as hardness, tensile strength, elongation and impact strength, they have a wide distribution range and a large selection of use. Because of its small specific gravity and high strength, plastics have a high specific strength. Compared with other materials, plastics also have significant shortcomings, such as easy burning, low rigidity, low aging resistance, and heat resistance.

The direction in which plastics can be developed can be summarized in two aspects. The first is the progressive function, that is, the existing types are modified by various methods to make their comprehensive functions improve; the second is to develop functions, that is, to carry out polymer materials with optical, electrical, magnetic and other physical functions, so that the plastics can have Photoelectric effect, thermoelectric effect, piezoelectric effect, etc.

Article from: Deyibao Hardware Rubber Factory   http://vspnof.cn/