Significance of Carbon Fiber Orientation on Thermomechanical Properties of Carbon Fiber Reinforced Epoxy Composite

The orientation of carbon fiber and its functional groups plays a crucial role in determining the thermomechanical properties of carbon fiber reinforced polymer (CFRP) composites. In this study, flat as well as curved CFRP with unidirectional (UD-CFRP), bidirectional (2D-CFRP), and combination of unidirectional and bidirectional (UD+2D)-CFRP were fabricated using filament winding technique to see the effect of carbon fiber orientation on the mechanical and thermomechanical properties. Three-point bending test shows that flat and curved UD-CFRP having all carbon fiber aligned in one direction exhibit superior mechanical as well as thermal properties. In flat UD-CFRP, improvement of 28%, 73.6%, and 14.3% in flexural strength, modulus and ILSS as compared to flat 2D-CFRP composite was observed. Optical microscopy and scanning electron microscopy (SEM) showed the delamination and fractured surface of CFRP. The maximum mechanical properties, glass transition temperature (Tg), coefficient of thermal expansion (CTE), and fiber-matrix interaction in UD-CFRP was explained by the degree of curing calculation using dynamic mechanical analysis (DMA). Raman spectroscopy was used to examine the defect difference created in CFRP composite with different orientation of carbon fiber, and the mechanism of fiber-matrix interaction was proposed. The improved thermal properties of CFRP composites were associated alignment of functional groups present on carbon fiber.