| Glass fiber reinforced polymer composites?GFRP?have been widely applied in many fields because of its excellent properties such as light weight,corrosion resistance,good electrical insulation,slow heat transfer,superior strength.However,the incompatibility of the inorganic nature of glass fiber with their organic feature leads to weak interfacial adhesion between matrix and fiber.To improve the interface of glass fiber-reinforced polymer composites,a coupling agent is commonly used to modify the glass fiber surface.But,the coupling-agent layer has low ductility and easily cracks,rendering the interface layer easily destructible when the counterpart composites applied at high temperature.The aim of this thesis is to modify the glass fiber surface and improve its wetting property with the resin matrix,and glass fiber reinforced composites were prepared using epoxy as matrix.Through researching of the composites on interface damage behavior at room temperature and high temperature,we attempt to explore the failure law of interface in actual application,and provide basic research on enhancing the interfacial property and heat-resistance of glass fiber-reinforced polymer composites.Primarily,on the basis of the study on character of glass fiber and epoxy,we designed and synthesized a kind of water-based hybrid sizing using a in-situ generated silica within the water-based EP?WEP/SiO2?.The structural morphology,thermal stability and mechanical properties of the cured films of hybrid sizing were investigated by scanning electron microscope?SEM?,Fourier transform infrared?FTIR?,thermal mechanical analyzer?TMA?,Thermogravimetric analyzer?TGA?and universal material testing machine.Results indicated the particles were uniform size and excellently dispersed in the cured films,and a good interfacial adhesion between inorganic particles and organic resin was observed.And also,when the content of silica was 10%,the thermostability and mechanical property of the cured film reaches its best performance.At 150 °C,the coefficient of thermal expansion of the cured film is 82.43×10-6/°C,falling in between glass fiber(2.62×10-6/°C)and epoxy matrix(147.76×10-6/°C).Then,the optimal formula of hybrid sizing selected was utilized to modify the glass fiber surface.The surface topography,wetting ability and mechanical properties of the coated GFs were characterized and analyzed through scanning electron microscope?SEM?,Atomic force microscopy?AFM?and Polarizing microscope.Results demonstrated that after modified by hybrid sizing,the single-GF tensile strength has no obvious increase,but the wetting ability can be significantly improved.Finally,the single glass fibers coated and the epoxy resin were prepared into the composite materials.The interfacial shear strength?IFSS?and cross-section topography of the single-GF/epoxy composites were analyzed by the fragmentation test in single fiber composites and the microstructure observation method at room temperature and 150 °C.Results indicated after modified by hybrid sizing,the ?membrane–particle? structure formed on the glass fiber surface was beneficial to improve the wetting quality between fiber and resin,enhance the mechanical combination force between the fibers and organic matrix and ease the mismatching of thermal expansion coefficients of organic matrix and inorganic GF.Ultimately,the interfacial shear strength?IFSS?of the single-GF/epoxy composites was increased by 52.6% and 68.9% at room temperature and 150 °C,respectively,which the designed water-based hybrid sizing can improve the interfacial property and heat resistance of glass fiber reinforced polymer composites. |
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