Effects of Glass Fiber Ratio on the Environmental Stress Cracking Resistance of Polycarbonates

ABSTRACT This study investigates the impact of glass fiber reinforcement on the environmental stress cracking (ESC) resistance of polycarbonate (PC) materials. Four variants were tested: unfilled PC and PC reinforced with 10%, 20%, and 30% glass fiber. Anticorrosion oil, commonly used in black oxide coating, served as the chemical agent to evaluate ESC effects. Specimens were injection‐molded and subjected to constant strains of 0.5%, 1.0%, and 1.5%, along with an unstrained control group, over 1 week. ESC resistance was analyzed visually and with optical microscopy, while tensile testing measured stress and elongation at break. Fourier transform infrared spectroscopy (FTIR) confirmed no chemical reaction between the oil and PC. Results revealed that anticorrosion oil is highly aggressive, with damage intensifying under higher strain levels. However, glass fiber reinforcement significantly improved ESC resistance, with higher fiber content providing enhanced protection. Post‐tensile test analysis identified matrix tearing, fiber‐matrix debonding, and fiber breakage as the primary damage mechanisms, observed consistently across materials. Representative SEM images highlighted these failure modes, offering valuable insights into the mechanical behavior of glass‐reinforced polycarbonate composites under stress. These findings underscore the critical role of glass fibers in enhancing polycarbonate durability under combined chemical and mechanical stress.