Organic-Inorganic Hybrid Copolymer Fibers and Their Use in Silicone Laminate Composites

Nonwoven organic-inorganic fiber mats of poly(methyl methacrylate)-graft-poly(dimethyl siloxane) copolymers with various PDMS contents were produced by the electrospinning process. The average fiber diameter increased from 0.7 to 3 mu m with increasing PDMS content. The fiber mats were used in the preparation of silicone-laminated composite materials by distributing them (single, double and triple layer mats) in a silicone matrix prior to thermal curing. The composites showed a remarkably good fiber distribution in the silicone matrix. In general the stiffness and strength increased in the presence of fiber, and surprisingly, so did the toughness/extensibility. An interesting feature was that the most silicon-rich fibers showed clear signs of yielding after tensile testing and failure. This, together with the greater compatibility of the fibers with the matrix because of the higher PDMS content, most probably favored composite toughness. All composite fracture surfaces were characterized by clear signs of fiber pull-out. Fracture initiation areas were difficult to locate, and this is accredited to an even distribution of the individual fibers in the matrix. POLYM. ENG. SC., 50:2143-2152, 2010. (C) 2010 Society of Plastics Engineers