Comparative Study of Commercial Glass Fiber-Reinforced Polyester Composite Beams: Thermal Behavior and Durability to QUV Exposure

Glass fiber-reinforced polyester (GFRP) composite beam is massively used in infrastructure because of its versatility. It is available in various matrices and fiber types and prices, so further research is required to understand the variations in its properties. This study examined two commercially available GFRP composite beams with a large price difference, almost 5 times. The inexpensive GFRPC was denoted as GFRPC 1 and the expensive GFRPC was denoted as GFRPC 2. Both composites employed unsaturated polyester, with a content of 36.53% and 36.02%, for GFRPC 1 and GFRPC 2, respectively. The glass fiber as filler was the same type, with a content of 62.19% and 63.98% for GFRPC 1 and GFRPC 2, respectively. Notably, GFRPC 1 exhibited combustible material of 1.28% during combustion from 600 to 900 °C in the presence of oxygen. Morphologically, more voids were seen in the cross-section area of GFRPC 2 than in GFRPC 1. The kinetic study of thermal degradation revealed that GFRPC 2 displayed slightly superior thermal behavior compared to GFRPC 1, with activation energy values of 103 kJ/mol and 112 kJ/mol, respectively. The changes were observed after 400 h of QUV exposure. The color changes observed were 1.68 for GFRPC 1 and 1.58 for GFRPC 2. The yellowish color on the composite surface exposed to UV light was confirmed through FTIR analysis. A decline in the storage and loss modulus curves occurred in GFRPC 1 compared to GFRPC 2. The GFRPC 1 and GFRPC 2 loss factor curves displayed a distinct behavior. In GFRPC 1, the 400-h QUV exposure impact results in a 50% increase in the loss factor curve. After QUV exposure to GFRPC 2, two peaks appeared on the loss factor curve. These peaks might be associated with a reaction product that can be seen in IR spectra.