[ACFREEZE]

Hi there and thanks for viewing my post,

I am having trouble with understanding something on the Formation of Rubber.

Part of the assignment I have been asked to do is on the Formation of Natural and Synthetic Rubber, I have to identify the similarities and differences between them, including Butyl Rubber.

If any one can help I would be grateful?
 

[mrdeadman]

the first thing you do is to refer to the chemistry book that you should have.

[wereworm73]

For the formation of natural rubber, do you need to explain how the rubber trees create cis-1,4-polyisoprene (the main component in natural rubber)?  Or is your assignment more concerned with the process of extracting this substance from the rubber tree latex and treating it?
 

[ACFREEZE]

Yes, I need some help with indentfying the differnces and simialrities in the formation (polymerisation) between Polyisoprene, polybutadiene, styrene-butadiene and butyl rubber.

I can't seem to get this, I know that styrene-butadiene is a copolymer and that the others are homopolymers but nothing else.

any help anyone can give would be great

[wereworm73]

A good place to start is to compare the monomeric units, initiators & catalysts used in the polymerization reactions.  Isoprene & 1,3-butadiene molecules are very similar.  In fact, isoprene is also known as 2-methyl-1,3-butadiene.  Not too surprisingly, both isoprene & butadiene can polymerize the same way (from 1,4-addition reactions), and both can even be vulcanized the same way.  It's just that with natural rubber, it's not going to involve the Ziegler-Natta catalyst used in making synthetic polymers.


By the way, butyl rubber is not a homopolymer.  It's really a copolymer of isobutylene & isoprene.