장기간 야외노출에 따른 탄소섬유/에폭시 복합재 적층판의 기계적 성능 열화 평가

Abstract

In this study, Carbon fiber/epoxy composites were exposed to the natural outdoor environment of Korea's southern coastal region for eight years to quantitatively evaluate the degradation of their mechanical properties and thermal stability. The specimens were subjected to environmental conditions involving simultaneous exposure to ultraviolet radiation, salt, and precipitation. Annual measurements were conducted to assess moisture absorption, tensile and compressive strengths, in-plane and interlaminar shear strengths, and Glass transition temperature (Tg). Cross-sectional analysis revealed that the surface protection film began to degrade after four years, while the internal Glass barrier remained structurally intact. Moisture absorption increased over the first four years and then gradually declined. Tensile and compressive strengths fluctuated within 5% of their initial values, and shear strengths remained stable within a +/- 10% range. Tg decreased by approximately 12% compared to unexposed specimens. This study provides empirical data on the long-term environmental degradation behavior of composites under real-world outdoor conditions that are difficult to replicate through single-factor accelerated aging tests.