Effect of Chlorinated Polypropylene as Compatibilizer on Mechanical Properties and Morphology of Kenaf Fiber Reinforced Polypropylene Composite

ABSTRACT The development of kenaf fiber (KF) reinforced polypropylene (PP) (KF/PP) composite is rapidly expanding due to its superior adaptability, sustainability, and excellent mechanical properties, making it a promising alternative to synthetic fiber reinforcements. However, poor interfacial bonding between KF and PP remains a major limitation due to the difference in chemical composition. To address this weakness, various contents of chlorinated polypropylene (CPP) (0, 5, 10, 15, 20 wt%) were incorporated into the KF/PP composite as a compatibilizer (cKF/PP) to improve the compatibility between KF and PP. The materials were compounded into pellets using a twin‐screw extruder at 190°C and subsequently molded into composite samples via injection molding at 230°C. Results showed that adding 15 wt% CPP significantly enhanced tensile strength, tensile modulus, flexural strength, and flexural modulus by 22.6%, 27.6%, 27.2%, and 28.1%, respectively, which also contributed to the increase in density. Scanning electron microscope analysis revealed an increase in PP adhesion, fiber dispersion, and aspect ratio in the presence of CPP. In addition, contact angle measurements showed that CPP increased the wettability and surface energy by 9.5% and 29.8%, respectively. Fourier transform infrared spectroscopy confirmed enhanced hydrogen bonding of hydroxyl groups due to improved fiber dispersion and interfacial bonding promoted by CPP. Thermal analysis demonstrated improved thermal resistance without significantly altering onset, degradation, or melting temperatures. These findings highlight the effectiveness of CPP in strengthening KF/PP composite, offering an efficient method to enhance interfacial bonding, making cKF/PP composites suitable for applications such as automotive interior components.