CF Modified With POSS And Its Effect On Interfacial Properties Of CF/UPR Composites

The carbon fiber reinforced unsaturated polyester resin(CF/UPR) composites were studied in this work. Different kinds of polyhedral oligomeric silsesquioxane(POSS) nanoparticles were introduced into the composites interface area by coating and chemical grafting to increase the interfacial strength and the mechanical properties of the composites.Four different nature of the POSS nanoparticles were chosen to coat on the carbon fiber surface. It can be found that methacryl POSS most increased the interfacial properties of composites among other three POSS through the characterization of surface morphologies, roughness, surface energy and interfacial and mechanical properties of the composites. Then the methacryl POSS was combined with epoxy resin to coat on the carbon fiber surface. The interlaminar shear strength of the composites is 28% higher than that of untreated carbon fiber composites after coating with epoxy resin and methacryl POSS.The spiro phosphate(SPDPC) with strongly polar groups of chloride and POSS nanoparticles with spatial structure were introduced on the fiber surface by chemical grafting, which improved the wettability of the fiber surface and mechanical locking, respectively. A large number of characterization methods such as SEM, AFM, Infiltration Meter and universal testing machine were used to characterize the performance of the composite interface in the view of the carbon fiber reinforced unsaturated polyester composites. Based on the interface theory the composites, it can be concluded that the surface roughness and mechanical interlockingof the fiber surface play more important role on CF/UPR composites.Monofunctional(methacrylolsobutyl) and multifunctional(methacryl) polyhedral oligomeric silsesquioxane(POSS) were successfully grafted on the CF surface to enhance the interfacial strength of CF reinforced UPR composites through coupling agent. The effects of two kinds of POSS on the surface morphology, roughness and surface energy of CFs with both kinds of POSS were almost the same, however, the ILSS and IFSS of composites grafted with multifunctional POSS were 8.0% and 6.9% higher than that of composites grafted with monofunctional POSS. The composites reinforced with multifunctional POSS grafted CFs not only increased surface energy and interfacial space interlocking properties between CFs and UPR, but also introduced chemical bonding on the interface.The different proportions of methacryl POSS were mechanically blended with unsaturated polyester resin to prepare resin casting and then the tensile strength of casting were tested. It is found that the appropriate proportion of methacryl POSS(5 wt %) could improve the tensile strength of the resin system. The activation energy was reduced after adding methacryl POSS to unsaturated polyester resin system from the calculation results, indicating that the methacryl POSS can react with resin in curing reaction. The CF/UPR composites with 5 wt % methacryl POSS were prepared to test the interlaminar shear strength of composites. The mechanical blend between POSS and UPR was observed to reduce the interface strength of composites.