Enhancement of polylactic acid (PLA) with hybrid biomass-derived rice husk and biocarbon fillers: a comprehensive experimental study

This study examines the effects of hybrid biomass-derived fillers on the mechanical, thermal, and water absorption properties of polylactic acid (PLA) matrix. The sustainable composites are made by the injection molding process by varying rice husk flour and its biocarbon percentage. The present hybrid composite, with 5% and 10% biocarbon reinforcement, achieves maximum tensile and flexural strengths of 61.2 MPa and 135.8 MPa, respectively, surpassing those of neat PLA by 105.6% and 104.8%. Beyond 10% biocarbon reinforcement, higher modulus values with a lower elongation percentage are seen, indicating that the material is stiffer and more brittle. The peak impact strength of 5.25 kJ/m2 is obtained with 10% carbon reinforcement but decreased at higher biocarbon percentages. Despite this, the biocarbon's increased stiffness resulted in superior hardness measurements at higher carbon percentages. Biocarbon's higher thermal stability also improves thermal transition and degradation properties. When the biocarbon content increased from 5 to 25%, the water absorption percentage is decreased. In comparison to hybrid composites with rice husk and biocarbon reinforcement, the composite containing 30% biocarbon exhibits poorer mechanical, thermal, and water-resistive properties. This indicates that the properties of PLA are significantly improved by filler hybridization using biocarbon, compared to using a single filler.