Effect of the Presence of a Silane Coupling Agent on Reaction Kinetics of Cationic Thermopolymerization of Epoxy Resin Adhesive

The effect of the presence of a silane coupling agent containing different functional groups on the reaction kinetics and physical properties of epoxy resin generated via cationic thermopolymerization was investigated. The kinetics of cationic polymerization of epoxy resin was studied using a nonisothermal DSC method. The polymerization is propagated by activated chain end (ACE) and activated monomer (AM) processes. With an increase in silane content, the ACE apparent activation energy first decreased and then increased, while the AM apparent activation energy increased. Moreover, the shear strength, coefficient of linear thermal expansion, gelation time, environmental testing of damp heat, and steady state with varied contents of silane coupling agents were evaluated. The results indicated that the presence of a silane coupling agent has more adhesion and lower water absorption than pure EP. The coefficient of linear thermal expansion and gelation time increased with the increase in silane content, while the water absorption decreased with the increase in silane content. Comparing the overall performance of three silane coupling agents used in the research, the curing system obtained by blending with vinyltrimethoxysliane (VTS) is a much better option for practical application as an adhesive.