DEGRADATION EFFECTS OF SOLAR RADIATION ON THE MECHANICAL PROPERTIES OF COMPOSITE MATERIALS: AN EXPERIMENTAL INVESTIGATION

This study investigates the degradation of the mechanical properties of composite materials based on para-aramid fiber Twaron CT 747 due to prolonged exposure to sunlight. Composite samples were fabricated using three manufacturing technologies: vacuum-assisted resin transfer molding (VARTM), autoclave curing, and hot-pressing. The mechanical properties were characterized through uniaxial tensile testing and flexural tests. The testing included reference samples (unexposed) and samples exposed to sunlight for 31 days and 122 days. The reference samples exhibited tensile strengths of 586.4 MPa (VARTM), 492.8 MPa (autoclave), and 399.6 MPa (hot pressing). After 122 days of sunlight exposure, tensile strength decreased by 29.6% (VARTM), 35.2% (autoclave), and 45.7% (hot-pressing), with the most significant decline in tensile modulus observed in the hot-pressed samples. Sunlight exposure also led to a reduction in flexural characteristics. Fractography analysis via scanning electron microscopy revealed layer delamination and the formation of microcracks, confirming the adverse effects of sunlight on material integrity. The findings of this study highlight the significant impact of prolonged solar exposure on the mechanical integrity of composite materials intended for outdoor applications.