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Do Elastomers Melt? (cis-polyisoprene / trans-polyisoprene)

Hi,

I hope you can help me...2nd year MechEng Student having a bit of misunderstanding of professor's notes

I'm under the impression that crosslinked polymers do not melt (Thermosets)

However, I'm not sure about vulcanized rubbers such as cis-polyisoprene (which has slight amounts of x-links)....I know by demonstration that such an elastomer has a Glass Transition Temperature, Tg but microstructurally I dunno how to explain the Tg and Tmelt of such a material because the x-links are throwing me off...

*I'm guessing since it's not extensively crosslinked, then the amorphous regions can slip past one another at high temperatures because of increased amounts of vibration*

Hope you understand what I'm trying to convey and please try to confirm if the statement between the asterisks is correct.

Thank you for any help, Benjamin

Reply to
Benjamin Bartolome
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I'm sorry....I realized that cis-polyisoprene decomposes/oxidizes but the trans- isomer has a T-melt

Please disregard the post

Thanks, Benjamin

Reply to
Benjamin Bartolome

cross posting to sci.chem. I'm not sure where my "rubber handbook" is...

Reply to
N:dlzc D:aol T:com (dlzc)

Crossposting to sci.polymers

The crosslinks make up a very small percentage of the molecule (~ 1%), but the rest of monomers are free to exhibit "normal" polymer behavior as much as possible. i.e., the segments between the crosslinks can show Tg and Tx behavior. The crosslinks however, will prevent large scale fluid flow.

John Aspen Research, -

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Reply to
john.spevacek

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