What causes pores on the surface of rubber products?
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Recently, while testing the molded specimens, I noticed many tiny pits on their surfaces, about the size of a needle tip. Changing the vulcanization temperature or increasing the pressure did not help to eliminate these pits. What could be the cause? Could anyone with expertise please provide an answer? + M2 p! D3 I) I: {7 L7 The M compound is nitrile rubber; there is no specific formula for it – we purchase the ready-made compounded rubber. When we reprocess it and cut the resulting pieces open, we find that the compounded rubber pieces are full of bubbles
Ugh, there are bubbles and you still increase the pressure? Lower the temperature and reduce the pressure to see if that works. This post was last edited by zhouchu2001 on 2009-3-26 17:05.]
Bubbles may form because there are volatile substances in the raw materials; when the temperature is high during the molding process, these bubbles appear and are unable to escape, thus remaining inside the finished product as bubbles.
After purification and mixing, the material is shaped into sheets; it is then turned into particles using a granulation machine, and finally dried in a dryer before being ready for use. If drying is not proper, bubbles will definitely form.
Are they residual monomers or solvents?
It might be that the rubber compound contains substances that are prone to decomposition; when heated, these substances evaporate and form bubbles, which in turn result in bubbles on the surface of the rubber products!
It is recommended that during reprocessing, reduce the roll spacing and pass the material as thinly as possible as many times as needed. However, be careful not to let the roller temperature get too high to prevent charring. If it still cannot be eliminated, it’s difficult to resolve at your current stage; you need to contact your raw material supplier.
You can try preheating first, applying pressure at low temperature, and then raising it to the specified temperature. Or control the heating rate and tabletting speed
It’s probably a problem with the compounded rubber; contact your supplier.