Day 28: Elastomers and Thermosets. What’s required for elastomeric behavior Essentials of elastomeric behavior Examples of Elastomers Example of a Thermoset. Thermosets and Elastomers. Both have some primary bonds between the chains.
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The double bond on the backbone is quite rigid and does not allow rotation from one form to the other.
One of these mers will result in a natural “curlique” to the chain. Do you see which?
As the Macrogalleria notes, extending a piece of rubber decreases its entropy.
Again we see the double bond on the backbone of the polymer and the cis configuration. It will be coily.
Widely used in automotive: tire treads, belts, hoses, gaskets, etc.
Like HIPS, but this one is a block, not a graft. In this case what happens is:
The polystyrene clumps together. These clumps do the job of crosslinks.
Can be recycled!!!
Copolymerize it with styrene in what’s called an alternating copolymer
It’s very light and tough.
The result is a 3D network solid. It will not soften and flow when heated. This is a thermoset.
Note that Epoxy is quite strong and stiff. This is, of course, the unreinforced stuff.
Electrical moldings, like some plugs
Matrix material for composites.
It’s like PE but with the H’s replaced by fluorines. (F). This makes for a strange substance.
Secondary bonding is very strong between the highly polarized F’s.
The bonding is such that no other substances are attracted. This accounts for the no-stick.