Mechanical, chemical, biodegradability and rheological characteristics of rice husk fibre-reinforced PLA bio-composites

In this study, rice husks from two different varieties were incorporated into PLA as reinforcing fibres using twin screw extrusion. The developed rice husk reinforced PLA composites were characterized for their thermal, mechanical, chemical, biodegradable and rheological characteristics. Thermal conductivities for the developed PLA rice husk composites were generally lower than 0.26 W/mK, but higher than that for neat PLA. Surface morphologies for the developed composites indicated presence of micropores and delamination indicating inadequate adhesion between the PLA matrix and the rice husk fibres. Broadening of the -OH peaks with an increase in rice husk fibres was observed in the FTIR spectra. The maximum stress for all the developed PLA rice husk composites was less than 67 MPa, the maximum stress for neat PLA, with PLA composites developed with 5% rice husks having the highest maximum stress for all composites developed. Modulus of elasticity increased with an increase in rice husk reinforcing fibres for both varieties. Biodegradation results indicated that the hydrophilic rice husks resulted in moisture ingression into the composites but would enhance hydrolytic degradation over a longer testing duration. The rheological results showed that an increase in rice husk fibre content reduced the flowability of the developed PLA rice husk composites, which affects their potential application.