DETERIORATION OF EPOXY-RESIN INDUCED BY M AGNETIC PARTICLES IN THE MIXING PROCESS

Adsorption of epoxy resin on magnetic particle surfaces and the deteri oration of epoxy resin induced by magnetic particles in the mixing pro cess of magnetic powder and epoxy resin with solvent were examined by GPC and FTIR measurements of the polymer removed from the mixture. Exp erimental results showed that small molecular weight polymers are adso rbed on the surfaces of magnetic particles more than large molecular w eight polymers, and that the polymerization and the ring-opening react ions of epoxy resin occur in the mixing process. The rate of these rea ctions depends on the kind of magnetic powder, and increases with incr easing temperature. Barium-ferrite particles accelerate the reactions more than Co-surface modified iron oxide and gamma-iron oxide particle s. Small molecular weight epoxy polymerizes more quickly than high mol ecular weight epoxy resin in the mixing process. The polymerization an d the ring-opening reactions are believed to be due to the catalyst-li ke nature of magnetic particles.