Han-Lang Wu

Study on the Polydimethylsiloxane Polyurethane Modified Novolac Type Epoxy Precursor for Manufacturing Carbon–Carbon Composites

The objective of this study is to investigate the feasibility of utilizing the aromatic amine-terminated polydimethylsiloxane polyurethane modified novolac type epoxy to prepare carbon–carbon (C–C) composite with improved mechanical and anti-oxidation properties. The curing kinetics of modified epoxy and the compatibility of polymer blend were investigated. Thermal, physical, and mechanical properties during the post-cure stage and carbonization stage were also examined. The curing kinetic studies show that epoxy matrix modified with polydimethylsiloxane polyurethane decrease the collision factor and increase the total heat of reaction and the active energy of reaction. Polydimethylsiloxane polyurethane is compatible with epoxy resin when the content is below 5 phr (parts per one hundred parts of epoxy resin). Adding polydimethylsiloxane polyurethane can reduce the weight loss of composite during the post-cure process. The volume shrinkage and porosity of carbon fiber reinforced composite and C–C composite decrease with the increase of polydimethylsiloxane polyurethane content. The polydimethylsiloxane polyurethane can increase the mechanical properties after carbonization since polydimethylsiloxane polyurethane releases the internal pressure and protects the fiber surface during the carbonization process. The novolac epoxy, with polydimethylsiloxane polyurethane modified, has better oxygen resistance and lower oxidation rate from the thermogravimetric analysis (TGA) oxidation testing results after the addition of this silicon-containing resin.