Reaction injection moulding elastomer products

The metathesis polymerisation of dicyclopentadiene, an inexpensive monomer (commercially available cyclopentadiene dimer produced by a Diels-Alder addition reaction containing ca 95 % endo and ca 5 % exo form), leads to a polymer that may be transformed into a technically useful elastomer [144-146, 179] and thermosetting resin [180,181]. The polymerisation has characteristics that make it readily adaptable to the reaction injection moulding ( rim ) process [182], The main feature of this process comes from the fact that the polymerisation is carried out directly in the mould of the desired final product. The active metathesis catalyst is formed when two separate reactants, a precatalyst (tungsten-based) component and an activator (aluminium-based) component, are combined. Monomer streams containing one respective component are mixed directly just before entering the mould, and the polymerisation into a partly crosslinked material takes place directly in this mould (Figure 6.5) [147,168,183-186],... 

At one time it seemed likely that the high-tra 5 polymer of cyclopentene formed in reaction (2) would find use as an all-purpose elastomer. Raw materials were cheap and the product had properties akin to those of natural rubber. However, its early promise has not been fulfilled. Other high-/ran5 polymers, such as those formed from norbomene, eqn. (11), and cyclooctene, eqn. (12), have found their way on to the market as components of elastomeric products, and the ROMP of enc o-dicyclopentadiene, eqn. (13), is being used to produce large objects by reaction injection moulding (RIM) see Ch. 17. 

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