Enhancement of Thermal Conductivity and Through-Thickness Mechanical Properties in Pitch-Based Carbon Fiber/Epoxy Composites via Stitching Process

초록

In this study, an I-shaped through-thickness stitched pitch-based carbon fiber (PCF)/epoxy composite is developed to simultaneously achieve through-thickness heat dissipation, in-plane heat spreading, and Mode I delamination resistance. By employing high-conductivity pitch-based carbon fiber bundles as both continuous through-thickness heat-transfer paths and crack-bridging reinforcements, the proposed composite improves directional thermal transport and resistance to opening relative to unstitched pitch-based laminates. Their exposed ends are compressed into I-shaped heads that anchor the stitches against pull-out. The stitch spacing is set to 10, 5, and 3 mm. Thermal conductivity is measured by laser flash analysis (LFA), and the Mode I response is evaluated by double cantilever beam (DCB)-type tests. Results demonstrate that the through-thickness conductivity increases from 1.73 to 5.30 W/m & centerdot;K and the in-plane conductivity from 100.69 to 140.84 W/m & centerdot;K, while the maximum opening load rises from 196.9 to 299.4 N at 5 mm spacing. A non-monotonic thermal-mechanical trade-off emerges at the narrowest stitch spacing.

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