What is the composition of the rubber grip on cameras?

I have a Nikon N80 that I recently took out to use and the rubber grip material is very sticky. I assume that it is reverting or decomposing. If it is a natural rubber that is vulcanized I will need to remove it. If it is a butyl rubber polymer mix, I may be able to seal it and continue using the camera as is. Anyone know what the composition of the grip material is?

Beyond rubber, the companies won't tell anyone, it's a bit like tyres.

I've been successful de-gooing my old (circa 1985) Nikon binocular rubber skin by aggressively rubbing the sticky parts with denatured alcohol and a Scotch-Brite pad until the sticky layer was removed. A year later, the rubber skin is still tack free.