Evaluation of the Mechanical and Biodegradation Properties of Kenaf Fiber‐Reinforced PLA Composites: An Experimental Study

ABSTRACT

Although Kenaf fiber‐reinforced polylactic acid (PLA) composites have been widely studied, the combined effects of untreated fiber content on mechanical properties, moisture sensitivity, and short‐term soil‐burial mass loss are still important for assessing their practical performance. In this study, PLA composites containing 20 and 30 wt.% untreated Kenaf fibers were prepared using a simple hot‐pressing method and evaluated under the same experimental conditions. Increasing the Kenaf content from 20 to 30 wt.% increased the tensile strength from 19.098 to 21.5 MPa and the tensile modulus from 500 to 800 MPa, representing improvements of 12.67% and 60%, respectively. The flexural strength increased from 92.7 to 126.3 MPa, while the flexural modulus increased from 1270.2 to 1382.6 MPa. However, this improvement in mechanical properties was accompanied by higher moisture sensitivity. After 30 days, the 30 wt.% composite showed approximately 210% water absorption, while the 20 wt.% composite showed approximately 200%. Over the same period, soil burial resulted in approximately 21% and 19% mass loss for the 20 and 30 wt.% composites, respectively. These results show a clear trade‐off between mechanical performance, moisture absorption, and degradation. Increasing the untreated Kenaf content improves the dry‐state strength and stiffness but also increases water absorption without causing a similar increase in short‐term soil‐burial mass loss. This combined assessment provides a practical basis for evaluating untreated hot‐pressed Kenaf/PLA composites for short‐service applications where mechanical performance, moisture exposure, and environmental degradation need to be considered together.