Mechanical and degradation properties of successive alkali treated completely biodegradable sisal fiber reinforced poly lactic acid composites

Abstract

The natural fiber reinforced biodegradable polymer composites were prepared with short sisal fiber as reinforcement in poly lactic acid (PLA) matrix. The sisal fiber is treated with 10% NaOH followed by H₂O₂. The composites were prepared with untreated and treated short sisal fibers at different weight proportions up to 25% in PLA matrix and investigated for mechanical and degradation properties. The results showed that the composite with treated fiber at 20% fiber loading has shown 30% and 8% higher tensile strength than neat PLA and untreated sisal/PLA composite, respectively. The flexural strength of treated sisal fiber composite at same weight fraction was 17% higher than that of plain PLA. The impact strength of composite with untreated fibers at 25% fiber loading was 107% high compared to that of neat PLA whereas the impact strength of treated sisal composite was reduced with increased fiber loading. The water absorption was high for untreated sisal/PLA composite compared to all other composites in the present study. Untreated sisal/PLA composite has high thermal degradation temperature compared to composite with treated fibers but lower than that of pure PLA. The enzymatic environment has increased the rate of degradation of composites. Surface morphology of tensile fractured and soil degraded surfaces of the composites were observed using scanning electron microscopy.