What are the heat resistance of the Silicone Mat?
Silicone Mat in the air heat resistance is much better than the organic rubber, at 150 ℃ its physical and mechanical properties of the basic constant, can be semi-permanent use, at 200 ℃ can be used continuously for more than 10000h; 380 ℃ can be segmented use. So that the Silicone Mat is widely used as a rubber component for high temperature applications.
Silicone Mat in the air at high temperatures (with oxygen) oxidation, due to the oxidation of methyl groups caused by the glue, so that products gradually hardened, and even cracking. And in the closed system of heat, the main depolymerization reaction occurs, so that products become soft, and even loss of mechanical strength. The heat resistance of the silica gel pad is related to both the type of the raw rubber, the vinyl content (crosslink density), the heat-resistant additive, the type and amount of the filler, and the pH value and water content of the compound. Therefore, the choice of raw polymer polymerization catalyst, the residual catalyst after the reaction, silica and other filler and structural control agent choice are very attention. Heat-resistant grade Silicone Mat, the high temperature (> 250 ℃) conditions, the hardness increase slowly, tensile strength and elongation at break and so on.
As the molecular structure of silicon raw material was non-crystalline, so the temperature of its performance is small, and has good cold resistance. Generally, the embrittlement temperature of the organic rubber is -20 ° C to -30 ° C, and the embrittlement temperature of the universal Silicone Mat is -60 ° C to -70 ° C. When 7.5 mol% of phenyl is introduced into the raw gum, the embrittlement temperature of the silica gel pad can be reduced to -115 ° C and maintained at -90 ° C and can be used.
Silicone Mat in the main chain of non-saturated keys, coupled with Si-O-Si bond on oxygen, ozone and ultraviolet light is very stable, and thus without any additives, that is, with excellent weather resistance. In the presence of corona discharge in the ozone, the organic rubber quickly aging, and thus the impact of the Silicone Mat is not serious. Prolonged exposure to ultraviolet light and wind and rain, the physical and mechanical properties of little change, the outdoor exposure test for decades, did not find cracks or degradation of sticky and other aging phenomenon.
Water vapor resistance
Silicone mats are resistant to low pressure water vapor (below 130 ° C), which is soaked in warm water and boiling water for a long time, with a volume increase of less than 1% and little impact on its mechanical and electrical properties. But more than 140 ℃ of water vapor that easily lead to Si-O-Si main chain break, so that the physical properties of silica gel pad quickly reduced. The water vapor resistance of the Silicone Mat is related to the type and amount of the filler used, the crosslinking density and the type of the vulcanizing agent.