rubber with zero memory?

May 28, 2005 5 Replies

in my experience nitrile rubber has some memory, i.e. when compressed for a period and then released, it doesn't (or doesn't immediately) return to exactly it's original shape. does anyone know of alternative types of rubbers that are much better at returning to their original shape? thanks



"bob" wrote ..

I understand silicon rubber is elastic. Perhaps you can check this out.

John

Dear bob:

It is informally called "taking a set". Using google advanced: with all the words: rubber compression set memory

URL:

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which claims that silicone rubber tends to not to take a compression set (as recommended by John C).

David A. Smith

Open cell foam elastomers are less likely to take a compression set than are closed cell foams, mostly because in being compressed for long periods the gases in closed cell foams tend to become forced through the thin cell walls, so that the gases "migrate" to areas of less compression. It's true that silicone rubbers are more resistant to such migration, but heavy compression can damage the closed cell structures and result in compression set. Some urethane open cell foams can actually perform pretty well as gasketing after being deflected 35% or more and they are excellent in resisting compression set. Poron foam

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is a good example, and there are various grades of Poron for various purposes. Even the best quality urethane open cell foams in proper compression don't perform well as gaskets in submerged applications, or when flexure is required.

Mark 'Sporky' Staplet>

I would call that a lack of memory. It does not remember to return to it's original shape. ;) But I'm nit picking.

Good luck, btw.

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