Explain why silicones have higher gas permeability than do ...

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Explain why silicones have higher gas permeability than do carbon-based molecules with equivalent pendent groups.
 
  What will be an ideal response?

Question 2

Explain why polybutadiene is softer than polyisoprene.
 
  What will be an ideal response?

Question 3

What do the initials DGEBPA stand for?
 
  What will be an ideal response?

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Answer to Question 1

The bonds along the silicone backbone (Si-O-Si) are longer than the bonds in the carbon polymer

Answer to Question 2

Polyisoprene, either cis or trans, has a methyl group that is pendent to the four-carbon backbone repeating unit of the polymer. Polybutadiene has no methyl group attached to its four-carbon repeating unit. This methyl group in polyisoprene interacts with other molecules as the molecules are moved past each other and also causes some restrictions to bending and twisting within each molecule. These intermolecular and intramolecular interactions cause the

polyisoprene to have higher energy that is manifested as higher hardness and higher tensile strength.

Answer to Question 3

Diglycidyl ether of bis-phenol A.

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Excellent

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