Role of Silanes in Polymer-Polymer Adhesion

Abstract

Organofunctional silanes are generally recommended as “coupling agents” in bonding organic polymers to mineral substrates. Certain silane primers that are effective in bonding two dissimilar polymers to glass are also effective in bonding the two polymers to each other. The higher melting polymer may be coated with a silane primer and contacted with molten lower-melting polymer. In some cases the silane adhesion promoter may be added to the lower melting polymer to obtain unprimed adhesion when fused against the other polymer. Two very dissimilar polymers (polyethylene and polybutylene terephthalate) may each be primed with appropriate silane primers and bonded by fusing a third polymer between them. Higher melting polymers may be fibers, films, or vulcanized elastomers including silicones. The mechanism of adhesion is believed to be formation of interpenetrating polymer networks between the primer and the other polymer phases.