Study On Carbon Fiber Reinforced Cyanate Ester Resin Matrix Thermal Conductive Composites

With the development of science and technology,many space vehicles put forward higher requirements for the thermal conductivity of composite materials.Cyante ester resins are used more and more widely in space due to their high dimensional stability and low space loss.Nowadays the study on thermal conductivity of cyanate ester stays at resin stage in China,not yet extent to the prepreg and fiber reinforced composites.It is of great importance to develop carbon fiber reinforced cyanate ester resin matrix thermal conductive composites.In this thesis,a new kind of bisphenol E cyanate ester with low viscosity at room temperature?RT?is chosen as main resin matrix,which is modified by graphite sheet,graphite powder,graphene and boron nitride fillers and reinforced by T700 carbon fiber.Then cyanate ester resin system,filler modified resin system and filler modified resin matrix carbon fiber reinforced composites are studied.The bisphenol E cyanate ester is liquid-like at RT,which has a low thermal conductivity of0.23W/?m·K?at RT,and has low water absorption and excellent dielectric properties.The bisphenol E cyanate ester fomulation system has been determined by adding 2-ethyl-4-methyl-imidazole catalyzer,and the modified resin system has high temperature resistance and excellent mechanical properties.It meets the need of RTM techniques at ambient injection temperature to fabricate quartz fiber reinforced resin matrix conposites,which belongs to high performance wave tranmitting composites.Through adding fillers,it is found that the viscosity of resin system by graphite sheet,graphite powder,graphene has rised violently,all having viscosity thresholds,which corresponds to nonlinear changes in the rheological properties of the filler-modified resin system.The viscosity rise of graphene modified resin is highest among them.As filler content increases,resin cast's thermal conductivity inceased significantly.Graphene modified resin inceases most obviously,up to 0.55W/?m·K?with only 1phr filler content.Addition of graphite powder could be up to 40phr,and the corresponding modified resin's thermal conductivity is 1.4W/?m·K?.Thermal conductivity in Z direction of fiber reinforced resin matrix composites increases rapidly with fiber volume fraction.When fiber volume fraction increases from 57.89%to72.80%,thermal conductivity in Z direction of fiber reinforced resin matrix composites increases from 0.69W/?m·K?to 1.21W/?m·K?.A thermal model of fiber reinforced resin matrix composites is proposed:?^-0.7=?1-V??₁^-0.7+V?₂^-0.7.Thermal conductivity in Z direction of composites with 57.89vol%fiber is 1.11W/?m·K?by adding graphite powder into CE system,which is lower than theoretical value.This is because adding graphite powder leads to a few voids inside the composites.The best carbon fiber reinforced cyanate ester resin matrix thermal conductive composites are prepared by improving fiber volume fraction and filler modification,the thermal conductivity of which is up to 1.61W/?m·K?,and have high compression strengh.