FLEXIBILITY IMPROVEMENT OF EPOXY-RESIN BY USING POLYSILOXANE-PGMA (MMA) COMPOSITE-PARTICLES

A study on the increase of the flexibility and decrease of the interna l stress of cured epoxy resins by addition of polysiloxane rubber part icles grafted with and without glycidyl methacrylate (GMA) or methyl m ethacrylate (MMA) is reported. Polysiloxane latex was obtained by cycl ing a mixture of polysiloxane containing a vinyl group and a =Si-H gro up, respectively, emulsifier, and water in a homogenizer. Graft. polym erization of GMA (or MMA) on these rubber particles was performed in t he latex under gamma-ray irradiation of Co-60. Th, rubber particles we re used to improve the flexibility of the epoxy resin. The particles g rafted with GMA showed a homogeneous distribution in the matrix, bette r inducing and terminating craze. Comparisons were made among the part icles grafted with MMA and various MMA-GMA or a series of GMA; the res ults indicated that the particles grafted with GMA (graft ratio = 10%) showed the greatest increase of elongation and decrease of internal s tress. The factors influencing the toughness of the epoxy resin matrix are discussed. (C) 1995 John Wiley and Sons, Inc.