A New Crosslinking Reaction of Polyacrylic Elastomer by Onium Salt Catalyst
Polyacrylic elastomer is a chemically saturated polymer of acrylic acid esters. Since esters are rather inert, other groups such as epoxy, halogen and carboxyl must be incorporated into the polymer to introduce sites for curing. We have studied the effect of various ammonium and phosphonium salt catalysts on the rate of crosslinking of polyacrylic elastomers which contain carboxyl and epoxy groups as cure-sites. We find that the catalytic activity of onium salts correlates with nucleophilicity of their anions.
The onium salt catalyzed reaction of a polyacrylic elastomer containing epoxy groups as cure-sites was enhanced by the addition of a dicarboxylic acid as an external crosslinking agent. This enhancement of cure rate decreased by increasing the,alkylene chain length of the dicarboxylic acid. This behavior can be explained by the dissociation constants, K1 and K2,of dicarboxylic acid.
KeywordsDicarboxylic Acid Epoxy Group Ethyl Acrylate Ethyl Acrylate Onium Salt
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