In the general plastics industry, plastics with low specific gravity such as PP and PE and relatively low surface hardness are called soft rubbers. And PS, ABS, AS, rigid PVC and other plastics can be called hard rubber. In fact, soft rubber and hard rubber are only relative terms. PE and PP referred to in the general plastics industry are soft rubbers. However, these materials can be regarded as hard materials compared to soft PVC, silicone, EVA, POE, TPES and other flexible plastics.
1. Temperature resistance
Silicone products are based on the silicon-oxygen (Si-O) bond as the main chain structure. The bond energy of the CC bond is 82.6 kcal/mole. The bond energy of the Si-O bond in the silicone is 121 kcal/g. Molecules, so the thermal stability of organic silicon products is high, and the chemical bonds of molecules will not break or decompose under high temperature (or radiation exposure). Silicone is not only resistant to high temperature, but also resistant to low temperature, and can be used in a wide temperature range. Whether it is chemical properties or physical mechanical properties, the change with temperature is very small.
2. Weather resistance
The main chain of organic silicon products is -Si-O-, and there is no double bond, so it is not easy to be decomposed by ultraviolet light and ozone. Silicone has better thermal stability, radiation resistance and weather resistance than other polymer materials. The life span of silicone in natural environment can reach several decades.
3. Electrical insulation performance
Silicone products have good electrical insulation properties. Their dielectric loss, voltage resistance, arc resistance, corona resistance, volume resistivity and surface resistivity are among the best in insulating materials, and their electrical properties are affected by temperature and frequency. The impact is very small. Therefore, they are a kind of stable electrical insulating materials, which are widely used in the electronics and electrical industries. In addition to excellent heat resistance, silicone also has excellent water repellency, which is a guarantee for high reliability of electrical equipment used in wet conditions.
4. Physiological inertia
Polysiloxane compounds are one of the most inactive compounds known. They are very resistant to biological aging, have no rejection reaction with animal bodies, and have good anticoagulant properties.
5. Low surface tension and low surface energy
The main chain of organosilicon is very flexible, and its intermolecular force is much weaker than that of hydrocarbons. Therefore, it has lower viscosity than hydrocarbons of the same molecular weight, weak surface tension, low surface energy, and strong film-forming ability. This low surface tension and low surface energy are the main reasons for its many applications: hydrophobicity, defoaming, foam stability, anti-sticking, lubrication, glazing and other excellent properties.
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Because silicone has the above-mentioned excellent properties, its application range is very wide. It is not only used as a special material for aviation, cutting-edge technology, and military technology, but also used in various sectors of the national economy. Its application range has been expanded to: construction, electronic and electrical, textiles, automobiles, machinery, leather and paper, chemical and light industry, Metal and paint, medicine and medical treatment, etc.