Effects of Chlorine Exposure on the Mechanical Properties of Polymer Composites

Abstract Thermoset-based polymer composites are widely used in automotive and aerospace engineering for their strength, durability, and resistance to environmental factors. They also serve in transporting liquids and chemicals, but their behavior under chemical exposure, such as chlorine-containing solutions, is less understood. This study investigates the impact of immersion in hypochlorite solutions (Clorox) on the flexural strength of aerospace-grade fiberglass polymer composites. Specimens were fabricated per ASTM D790 standards and immersed in Chlorine solutions at 25%, 50%, 75%, and 100% concentrations for 24, 48, and 96 hours. Changes in mass were recorded to track chlorine absorption, and flexural tests assessed mechanical performance. The results demonstrated significant deterioration in flexural strength, with higher concentrations and longer exposures causing greater damage. The observed degradation was linked to chlorine absorption, which weakened the fiber-matrix interface and chemically deteriorated the matrix. This study highlights the critical need to consider long-term chemical exposure when selecting materials for aerospace applications. By identifying the thresholds at which chlorine-induced degradation becomes critical, the research provides valuable guidance for improving the durability and reliability of polymer composites in aggressive environments.