Enhancing the UVA Induced Durability of GFRP Composites for Outdoor Applications: Effects of Light Stabilizer Type, Content Variation, and Hybrid Fo

ABSTRACT

The long‐term performance of glass fiber reinforced polymer (GFRP) composites in outdoor applications is often compromised by ultraviolet (UV) induced degradation, leading to surface discoloration and deterioration of mechanical properties. This study investigates the enhancement of both esthetic and mechanical durability of chopped glass fiber/polyester composites through the incorporation of two UV stabilizers benzotriazole (BZ) and bis(2,2,6,6‐tetramethyl‐4‐piperidyl) sebacate (SEB), used individually and in a hybrid (HYB) formulation. Composites with varying stabilizer contents (0.5, 0.7, and 1.0 wt%) were fabricated via hand lay‐up and subjected to 1000 h of accelerated UVA exposure in accordance with ASTM G154. Surface color stability (Δ E ), thermomechanical behavior, and flexural properties were evaluated before and after exposure, alongside microstructural and elemental characterization. Results show that HYB (1.0 wt%) achieved the superior color stability (~68% improvement), higher damping factor (tan δ ), and excellent retention of flexural strain at peak (~93%), owing to combined or complementary UV absorption and radical scavenging mechanisms. Among the individual stabilizers, BZ (0.5 wt%) provided the highest color stability (~63% improvement) compared to the neat composite, while SEB offered moderate improvement through free radical suppression. These findings demonstrate that tailored combinations of UV stabilizers can significantly enhance the long‐term durability of GFRP composites, providing practical design guidelines for outdoor structural and esthetic applications.