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Improvement of Fracture Toughness and Thermo-mechanical Properties of Carbon Fiber/Epoxy Composites Using Polyhedral Oligomeric Silsesquioxane (Poss)

Temesgen, Tesfahun Derbew
In this study the interlaminar region of carbon fiber/epoxy laminate was modified using a simple technique of Painting or spraying different POSS- PVP solutions. It was observed that the application of only PVP film in the interlaminar region increased the interlaminar fracture toughness of the carbon fiber epoxy composites by 33%. But, the addition of POSS particles to PVP further improved the fracture toughness up to 93%.It was also observed that, even though the maximum fracture toughness was obtained through a POSS with one epoxide group. Satisfactory results were also obtained by the addition of a POSS type with a non-epoxide but highly reactive functional group (MA POSS) and with the incorporation of POSS with no reactive groups (PEG) POSS. The SEM of the fractured surfaces also supported this hypothesis. Regarding the thermo-mechanical properties, DMA results showed improvement storage modulus of the carbon fiber/epoxy composites with the addition of PVP/POSS in the interlaminar regions. It was also observed from the DMA results that the percentage loading of POSS didn't affect the glass transition temperature of the composites considerably and the change in glass transition was mainly due to the addition of PVP.