• Composites Research
• /
• v.30 no.3
• /
• pp.175-180
• /
• 2017

Currently, since carbon fiber reinforced plastics (CFRPs) are lightweight and have excellent physical properties, their demand has increased dramatically. Many works have studied the CFRPs based on recycled thermoplastics. In this study, the applicability of recycled composite was evaluated using recycled polyethylene terephthalate (PET). PET was collected from waste materials used in beverage bottles and processed to produce PET films. Optimal thermoforming temperature and time were analyzed by comparing the mechanical properties with forming temperature and time difference for producing PET films. CF mat and PET film were used to determine the suitable parameters for the optimum thermoforming of CF/PET composites. The mechanical properties of each thermoforming condition were verified by bending test. The degree of impregnation of the PET film into the CF mat was evaluated by cross-sectional photographs, whereas the interfacial properties were evaluated by interlaminar shear strength (ILSS). Ultimately, it was confirmed that the thermoforming condition for forming the CF/recycled PET composites yielding the optimal mechanical and interfacial properties was at $270^{\circ}C$ for 5 minutes.

• Composites Research
• /
• v.29 no.3
• /
• pp.111-116
• /
• 2016

The tilting pad journal bearing for the turbo compressor application has a role to support high speed and heavy loading rotor. White metal has been widely used for the bearing material but the conventional bearing is immediately suspended and induces serious serious damage to the rotor under the unexpected oil cut situation or the insufficient oil film formation. The carbon fiber reinforced composite having high specific stiffness, specific strength and excellent tribological characteristics can solve these seizure problems. In this work, the study on the durability of high thermal resistance carbon fiber/epoxy composite tilting pad journal bearing under oil cut situation was conducted. The material properties of the composite materials including tensile, compressive and interlaminar properties were measured at room and high temperature of oil cut situation. To investigate the possibility of failure of composite tilting pad journal bearing under oil cut situation, the stress distribution of the composite bearing was analyzed via finite element analysis and the Tsai-Wu Failure index was calculated. To verify the failure analysis results, the oil cut tests for the composite tilting pad journal bearing were conducted using industrial test bench.

• Korean Journal of Materials Research
• /
• v.4 no.3
• /
• pp.287-294
• /
• 1994

PAN-based carbon fiber roving and fabric were heat treated at the temperature of $2170^{\circ}C$. Using non-heat treated and heat treated fabric, greenbodies of CFRP and GFRP were manufactured in the Autoclave. After the analysis of heat treated and non-heat treated carbon fiber roving and two types of greenbodies, the variations of physical and mechanical properties of carbon fibers and greenbodies with heat treatment were studied. Observing the cross-section of carbon fiber with SEM, we knew the diameter of carbon fiber was decreased from 6.8gm to 6.4p1. The results of TGA showed that the oxidation resistence was enhanced after heat treatment. The tensile strength of carbon fiber was decreased from (3.11$\pm 0.32)\times 10^3$ MPa to (1.87$\pm 0.26)\times 10^3$MPa, but tensile modulus was increased from (1.94$\pm 0.06)\times 10^5$ MPa to (2.02$\pm 0.11)\times 10^5$MPa after heat treatment. The interlaminar shear strengths of CFRP and GFRP were 148.8$\pm$1.6Mpa and 82.2$\pm$1.1Mpa, respectively. Torch test showed that CFRP was abraded smoothly but GFRP was delaminated.

• Composites Research
• /
• v.28 no.4
• /
• pp.232-238
• /
• 2015

As a new method to predict the degree of dispersion in carbon nanocomposites, the electrical resistance (ER) method has been evaluated. After CNT epoxy resin was dropped on CF tow, the change in electrical resistance of carbon fiber tow was measured to evaluate dispersion condition in CNT epoxy resin. Good dispersion of CNTs in carbon nanocomposite exhibited low change in ER due to wetted resin penetrated on CF tow. However, because CNT network was formed among CFs, non-uniform dispersion occurred due to nanoparticle filtering effect by CF tow. The change in ER for poor dispersion exhibited large ER signal change. The change in ER was used for the dispersion evaluation of CNT epoxy resin. Correlation between interlaminar shear strength (ILSS) and dispersion condition by ER method was established. Good CNT dispersion in nanocomposites led to good interfacial properties of fiberreinforced nanocomposites.