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    Physicomechanical Characteristics of Carbon Fiber Reinforced Polymer Composite Using X-Ray Diffraction, Atomic Force and Electron Microscopies
    (2022-10-01)
    Lin, Ye Htet
    ;
    Karin, Preechar
    ;
    Larpsuriyakul, Patcharee
    ;
    Ohtake, Naoto
    The physicomechanical characteristics of PAN-based carbon fibers were investigated by SEM-EDS, XRD, TEM and AFM analysis while the mechanical properties of the composites were studied by tensile, flexural and Charpy impact tests with ASTM standards. Regarding the tensile test of carbon fiber fabric, the average tensile strength of CF-I, CF-II and CF-III fibers were around 147 MPa, 137 MPa and 225 MPa and the tensile modulus of those were 12.8 GPa, 13.2 GPa and 12.8 GPa, respectively. Later, the nanostructure of carbon fiber was recognized not as a pure graphite carbon structure because they mixed with graphite and amorphous structures. The higher tensile strength and modulus of CF-III fiber fabric was lower interlayer spacing (d002) because it consisted of more graphene layers in the graphite structure when compared with CF-I and CF-II fiber fabrics. Concerning AFM analysis’s results, CF-I fiber fabric has higher surface roughness (Ra) of 34.8 nm and more in-depth with wider pit lines along the fiber axis, which caused higher mechanical properties among the three composites. According to this article, the nanostructure of carbon fibers had a lower impact on CFRP composite because the interfacial bonding between fiber and epoxy matrix, which obtained the higher mechanical properties in the composite, was directly enhanced by the higher surface roughness of the fibers.
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    A Study on Curing Temperature and Fracture Mechanism of Carbon and Glass Fiber Reinforced Polymers Using an Electron Microscopy
    (2021-06-01)
    Man, Tial Cuai
    ;
    Karin, Preechar
    ;
    Lin, Ye Htet
    ;
    Larpsuriyakul, Patcharee
    ;
    Ohtake, Naoto
    The morphology and nanostructure of carbon and glass fiber are investigated by using XRD, SEM and TEM analysis. The composites are divided into three groups which consists of “without post-curing”, “post-cured at 80 °C for 6 hrs” and “post-cured at 120 °C for 3 hrs” to investigate curing temperature effect. The mechanical properties of composites are tested in the indentation, tensile, and flexural machine with ASTM standard. According to the results, the hardness of post-curing of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) are increased approximately three-times and 5 % compared to with and without post-curing process. The tensile strength of CFRP and GFRP are approximately 458 MPa and 385 MPa, while post-cured at 120 °C for the three-hour results are 490 MPa and 433 MPa respectively. In contrast, composites of treated fiber are not improved mechanical strength significantly for CFRP, while GFRP are slightly increased by 7 %. On the other hand, the flexural strength of treated carbon and glass fiber of composite are increased to 3 % and 15 % respectively. Higher temperature and treated fiber composites of carbon fiber are not significantly improved because high temperature curing and treated fiber created more porous to occur fracture internally.
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