Mechanical and Electrical Properties of Graphite/Epoxy Composites

• Main Authors: Jiang, Bo-Xian, 江柏賢
• Other Authors: Yeh, Meng-Kao
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/60925282980253269511

碩士 === 國立清華大學 === 動力機械工程學系 === 100 === Mechanical stength, electrical conductivity, thermal conductivity of matrix used in polymeric composite materials are not so good. Graphite with good mechanical properties, low electrical resistivity, high temperature resistance is cheaper than carbon nanotubes. This study used epoxy, 20 μm natural graphite, expanded graphite, and carbon fiber to fabricate natural graphite/epoxy and expanded graphite/ epoxy composites and carbon fiber/natural graphite/epoxy composites. Different percentages, (0, 10, 15, 20, 25, 30, 35, 40 wt%) of natural graphite and (0, 10, 15, 20 wt%) of expanded graphite in composites, was assessed to discuss the effect on their mechanical and electric properties. Modified Halpin–Tsai equation was used to fit the Young’s modulus and flexural modulus of the natural graphite/epoxy composites by adopting an orientation factor and an exponential shape factor in the equation. The results of 40 wt% natural graphite/epoxy composites showed that the Young’s modulus increased 201.11%, the flexural modulus increased 270.14%, the tensile strength decreased 21.36%, the flexural strength decreased 34.65%, the volume resistance decreased 99.99%. The results of 20 wt% expanded graphite/epoxy composites showed that the Young’s modulus increased 105.07%, the flexural modulus increased 150.91%, the tensile strength decreased 23.88%, the flexural strength decreased 31.74%, the volume resistance decreased 99.99%. And results of carbon fiber/natural graphite/epoxy composites’ properties satisfied the bipolar plates 2017 targets of US Department of Energy. In addition, the Young’s modulus of natural graphite/epoxy composites were also analyzed using the finite element software ANSYS.