What Type of Rubber?

[Bob Scott]

Hi Guys,

When real rubber gets old it dries up and cracks. There is a kind of artificial rubber that turns into a black viscous flowing ooze. Ocasionally, I used to see black "rubber" tape recorder belts melt down this way due to their age. Does anyone know what type of rubber this is?

I looked behind my old phono turntable yesterday. On the spare cartridge shell was a blob of this black sticky gunk. I have no idea what it used to be, what function it performed, or what shape it was before it turned into ooze. Hmm. Maybe a spare belt?

[haklesup]

probably a partially vulcanized rubber (latex) with carbon fillers and plasticizers to keep it flexible. The goo is probably a mix of the carbon and stabilizers after the natural rubber has fully oxidized.

Today a synthetic rubber like a silicone or butyl would be used or a fiber reinforced synthetic rubber. I doubt natural rubber used for very much anymore in electronics.

[Externet]

One of many explanations on the net

-----> http://www.bigsiteofamazingfacts.com/wh ... he-process