Poly(dimethylsiloxane) as Interphase in Carbon Fiber-Reinforced Epoxy Resin: Topographical Analysis and Single-Fiber Pull-Out Tests

Abstract

Covalently bonded polydimethylsiloxane on carbon fibers presents a low friction, elastomeric interphase in carbon fiber reinforced plastics. Polydimethylsiloxane is a well-known material in terms of low friction and its use as slip additive. Using polydimethylsiloxane as interphase in composites decreases frictional sliding and reduces interface abrasion. Different polydimethylsiloxane polymers were used and analyzed concerning reaction yield, functional groups, molar masses and molecular structures. The polymer grafting created characteristic nanoscaled patterns on the carbon fiber surface, which depend on the structure of the polydimethylsiloxane species and were analyzed with atomic force microscopy. The change in polarity from unsized carbon fibers to polydimethylsiloxane coated fibers was observed via contact angle measurements: increases in hydrophobicity up to 120° were noted. Furthermore, the fiber-resin interactions were directly influenced by the polydimethylsiloxane coating and led to a decreas...