Common Problems of Condensation Cure RTV-2 Silicone Rubber

A. Insufficience of heat resistance. Condensation RTV-2 silicone rubber could bear the temperature of 250℃ if properly used, otherwise the heat resistance will plunge even until below 120℃, which is caused the by the reason that the ethanol vapour that was released in the process of condensation degradates the silicon rubber. As a result, the ethanol vapour won’t diffuse completely and can’t completely vulcanize the silicon rubber in deep layer causing the phenomenon of being softened and sticky, if seal the electrical elements too fast or make a too big potting deepness or too small ventilation area. Therefore, the potting elements should first keep in the room temperature for 1-2 days, then make the outer shell to seal the elements. Or you can heat it under the condition of 60~100℃ for several hours.
B. Electrical property plunge badly. This is caused by the reason mentioned above, so don’t seal the electrical elements too fast.
C. The vulcanization rate. We could change this rate by adjust the curing temperature or the dosage of the catalyst, but we should mind that the addition of catalyst can shorten the operation time, so we should pay attention to it.
D. Bi-component RTV-2 silicone rubber belongs to the category of condensation silicon rubber and will release the byproduct of low molecular substances. Therefore the electrical insulating property will decrease and can get over to a normal level after the byproduct volatilizes(namely the silicone rubber gets fully cured ).
E. When we select the base material, we should take into consideration that if the byproduct of ethanol, water and hydrogen that released by the process of vulcanization will do harm to the base material.
F. Bi-component RTV-2 silicone rubber has merits of good ventilation and moisture penetrability, and its penetrability for O2、CO2 and H2O is better than other high molecular material, so we should consider that if it will cause bad influence.
G. Condensation silicone rubber potting materials release low molecular substances, so it will somewhat shrink, which on this point is not good as the addition cure silicone rubber potting materials.