AS Chemistry - CourseworkOpen Book Paper 1. There are two types of rubbers, natural and synthetic rubber. Natural rubber is predominantly

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AS Chemistry – Coursework

Open Book Paper

1. There are two types of rubbers, natural and synthetic rubber. Natural rubber is predominantly obtained from the Hevea brazilinesis tree, which originates from South America. Natural is obtained as latex, a colloidal dispersion of nanoscale rubber particles in water. C.D Harries showed that natural rubber consists of repeating units, which are joined together in long rings, as shown below.         

During this reaction the two double bonds are broken in the isoprene and poly(isoprene) forms only 1 double bond in its repeating unit.

 

CH3                                   H                                            CH3                        H

        

H2C                CH2                                         CH2                      H2C        

            Isoprene                                                 Poly(isoprene)

  (2-methylbuta-1,3-diene)                                          Natural Rubber

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Synthetic rubber is man made and was first produced by carrying out the polymerisation of dienes (alkenes containing 2 double bonds.) Below is the reaction of a synthetic rubber being polymerised.

H                       H                                              H                         H        

H2C                    CH2                            ...

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