The carbon fibers (CFs) are widely used in applications that require superior mechanical properties in lightweight materials, and they are ideal reinforcement materials in advanced polymer matrix composites. CF-reinforced polymer matrix composites (CFRPs) are emerging as promising materials with bro...
The carbon fibers (CFs) are widely used in applications that require superior mechanical properties in lightweight materials, and they are ideal reinforcement materials in advanced polymer matrix composites. CF-reinforced polymer matrix composites (CFRPs) are emerging as promising materials with broad industry applications, including military supplies, aerospace, ships, and sporting goods. Recently, their production cost has been greatly reduced due to developments in CF manufacturing technologies, which has further expanded their application to various fields, including the automobile industry.
In this study, surface defects and the surface layer of CFs were etched, using a well-known electrochemical oxidation method, ammonium bicarbonate, to enhance mechanical properties. The change in surface properties, microstructures, and mechanical strength were evaluated after the treatment. The mechanical interfacial strength of the modified CFs was also investigated by determining the interfacial shear strength (IFSS). Surface roughness, average surface charge, and/or surface free energies of the CFs were dramatically altered, depending upon etching process conditions. CF tensile strength and IFSS increased significantly in a certain range after etching. The electrochemical modification of CFs primarily removed surface defects and amorphous structures, while enhancing surface functional groups and crystalline-rich microstructures.
The compositional effects on the cure behaviors and mechanical properties of CF-reinforced nylon6/epoxy composites were also investigated. Ethanol was used as a melting agent for nylon6 (alcohol-soluble nylon), and a nylon6 content of 0 to 50 wt.% was used in the mixture. The curing properties of the blend system were investigated by differential scanning calorimetery (DSC), thermogravimetric analysis (TGA), and fourier transform infrared spectroscopy (FT-IR). The surface morphologies of the fractured surfaces were observed by scanning electron microscopy (SEM). The mechanical properties of the composites were measured with the Charpy pendulum impact test to determine the cumulative energy absorption until final destruction of the composites. The Charpy energy of the N4:E6 sample was enhanced by 52% compared to that of pure epoxy. This is due to the curing relation between the composition of nylon6 and epoxy.
In order to develop high quality materials that display electromagnetic interference shielding (EMI-S), Ni-plated CF fabrics (Ni-CFFs) were prepared using the electroless method. The effects of post heat-treatment conditions on EMI-S efficiency (EMI-SE) and electrical conductivity of the Ni-CFFs/epoxy composites were then investigated. The morphologies and structural properties of Ni-CFFs were measured by SEM and XRD. It was found that all Ni peaks increased with increasing post-heat treatment temperature, indicating that impurities were removed and nickel particle sharp crystalline peaks. Also, It was found that the EMI-SE of composites was increased after post heat-treatment. The EMI-SE of post-heat treated Ni-CFs was increased in the frequency range of appliance electromagnetic waves (3.0 × 107 to 6.0 × 108 Hz), indicating that the EMI-SE of the composites can be enhanced by modulating the microstructure of Ni.
In order to manufacture high-quality recycled CFs (R-CFs), CF-reinforced composite wastes were pyrolyzed with superheated steam at 550 °C in a fixed bed reactor for varying reaction times. The mechanical and surface properties of R-CFs were then characterized with a single fiber tensile test, analysis of their IFSS, SEM, and X-ray photoelectron spectroscopy (XPS). The surface analysis showed that there was no matrix char residue on the fiber surface. The tensile strength and IFSS values of the R-CFs were 90% and 115% of the virgin carbon fibers (V-CFs), respectively. The recycling efficiency of R-CFs from the composites was strongly dependent on the pyrolysis temperature, reaction time, and superheated steam feeding rate.
The carbon fibers (CFs) are widely used in applications that require superior mechanical properties in lightweight materials, and they are ideal reinforcement materials in advanced polymer matrix composites. CF-reinforced polymer matrix composites (CFRPs) are emerging as promising materials with broad industry applications, including military supplies, aerospace, ships, and sporting goods. Recently, their production cost has been greatly reduced due to developments in CF manufacturing technologies, which has further expanded their application to various fields, including the automobile industry.
In this study, surface defects and the surface layer of CFs were etched, using a well-known electrochemical oxidation method, ammonium bicarbonate, to enhance mechanical properties. The change in surface properties, microstructures, and mechanical strength were evaluated after the treatment. The mechanical interfacial strength of the modified CFs was also investigated by determining the interfacial shear strength (IFSS). Surface roughness, average surface charge, and/or surface free energies of the CFs were dramatically altered, depending upon etching process conditions. CF tensile strength and IFSS increased significantly in a certain range after etching. The electrochemical modification of CFs primarily removed surface defects and amorphous structures, while enhancing surface functional groups and crystalline-rich microstructures.
The compositional effects on the cure behaviors and mechanical properties of CF-reinforced nylon6/epoxy composites were also investigated. Ethanol was used as a melting agent for nylon6 (alcohol-soluble nylon), and a nylon6 content of 0 to 50 wt.% was used in the mixture. The curing properties of the blend system were investigated by differential scanning calorimetery (DSC), thermogravimetric analysis (TGA), and fourier transform infrared spectroscopy (FT-IR). The surface morphologies of the fractured surfaces were observed by scanning electron microscopy (SEM). The mechanical properties of the composites were measured with the Charpy pendulum impact test to determine the cumulative energy absorption until final destruction of the composites. The Charpy energy of the N4:E6 sample was enhanced by 52% compared to that of pure epoxy. This is due to the curing relation between the composition of nylon6 and epoxy.
In order to develop high quality materials that display electromagnetic interference shielding (EMI-S), Ni-plated CF fabrics (Ni-CFFs) were prepared using the electroless method. The effects of post heat-treatment conditions on EMI-S efficiency (EMI-SE) and electrical conductivity of the Ni-CFFs/epoxy composites were then investigated. The morphologies and structural properties of Ni-CFFs were measured by SEM and XRD. It was found that all Ni peaks increased with increasing post-heat treatment temperature, indicating that impurities were removed and nickel particle sharp crystalline peaks. Also, It was found that the EMI-SE of composites was increased after post heat-treatment. The EMI-SE of post-heat treated Ni-CFs was increased in the frequency range of appliance electromagnetic waves (3.0 × 107 to 6.0 × 108 Hz), indicating that the EMI-SE of the composites can be enhanced by modulating the microstructure of Ni.
In order to manufacture high-quality recycled CFs (R-CFs), CF-reinforced composite wastes were pyrolyzed with superheated steam at 550 °C in a fixed bed reactor for varying reaction times. The mechanical and surface properties of R-CFs were then characterized with a single fiber tensile test, analysis of their IFSS, SEM, and X-ray photoelectron spectroscopy (XPS). The surface analysis showed that there was no matrix char residue on the fiber surface. The tensile strength and IFSS values of the R-CFs were 90% and 115% of the virgin carbon fibers (V-CFs), respectively. The recycling efficiency of R-CFs from the composites was strongly dependent on the pyrolysis temperature, reaction time, and superheated steam feeding rate.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.