Preparation And Properties Of Nylon12and Epoxy Resins Thermally Conductive Composites

In recent years, with the development of science and technology, there is thegrowing demand for thermally conductive materials. In the filed of electronic andelectrical, materials are required to be thermally conductive, excellent adhesion aswell as processsing. As the Integration and mounting technology develop rapidly, thevolume of electronic component and logic circuit decreases significantly. To ensurethe proper divice operation, the unwanted heat must be remvoved and the thermallyconductive materials are in great need. The commnonly used materials have apparentweakness. The metal such as copper is vulnerable to corrosion, and the ceramic arefragile. As a result, new materials which possess excellent comprehensive propertiessuch as light weight, corrosion resistance and easy processing are required apart fromhigh thermal conductivity. In the study, our interest to improve the thermalconductivity of polmer is focused on the selective addition of high thermal conductivefillers, such as carbon fiber and graphene.Firstly, Carbon fiber/Nylon12composites were prepared via melting compounding.Thermal conductivity, electrical resistivity, thermal properties, mechanical property ofcomposites with different Carbon fiber content were studied. Our results showed thatthe thermal conductivity of composites improve remarkablly with increasing contentof carbon fiber. Due to the anisotropy of carbon fiber, the carbon would orient in theflow direction during the processing, which resulted in the huge diffence of thermalconductivity in different direction. When the filler content reached the47.4vol%, thein-plane and through-plane thermal conductivity is3.425and1.502W/(m·K)respectively. The addition of carbon fiber could increae the heat distortiontemperature and improve heat stability of nylon12. When filler content reached the47.4vol%, the heat distortion temperature increased by77.6℃but maintained theequivalent tensile strength of pure nylon12. The carbon fiber could work as nucleaterand decreased crystallization temperature. However, the larger content of carbon inthe nylon12improved the viscosity of composites and led to the reduction ofcrystallinity. In the meanwhile, the incopration of carbon fiber could improve theshear viscosity, storage as well as loss modulus.Secondly, dopamine (DA) was used as reducing agent and modifier for grapheneoxide (GO) to prepare the dopamine reduced graphene oxide (PDA-GO) whichavoided the environmentally harmful reducing agents and address the problem ofaggregation of graphene in composites. Then PDA-GO was incorporated into epoxy resins to produce PDA-GO/epoxy composites. The effect of PDA-GO on theproperties such as curing properties, thermal conductivity, filler dispersion and so onwere investigated in details. The results showed: XRD, Raman and UV-vismeasurement indicated the complete exfoliation of PDA-GO sheets, and the π-π hadresoted. FT-IR and XPS exhibited that GO had been thoroughly reduced. In addition,the reduced GO had been functionalized with oxidated DA. TEM images revealedPDA-GO could homogenously disperse in the epoxy matrix. And DSC curves showedexothermal peak shifted to lower temperature indicating that PDA-GO would act as acatalyst to accelerate the curing reaction. Finally, the addition of PDA-GO alsoimproved the thermal conductivity, dynamic mechanical and thermal stability as well.