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

Question

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

Benjamin Bartolome · Accepted Answer

I'm sorry....I realized that cis-polyisoprene decomposes/oxidizes but the trans- isomer has a T-meltPlease disregard the postThanks,Benjamin

N:dlzc D:aol T:com (dlzc) · Answer

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

john.spevacek · Answer

Crossposting to sci.polymersThe crosslinks make up a very small percentage of the molecule (~ 1%),but the rest of monomers are free to exhibit "normal" polymer behavioras much as possible.  i.e., the segments between the crosslinks canshow Tg and Tx behavior.  The crosslinks however, will prevent largescale fluid flow.JohnAspen Research, - "Turning Questions into Answers"Opinions expressed herein are my own and may not represent those of myemployer.

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

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