Recycling and degradation behaviour of the bamboo fibre reinforced green composite fabricated by injection moulding

The present investigation evaluates the mechanical, thermal, morphological, and crystalline behaviour of green composite reinforced with bamboo fibre under recycling and various environmental conditions. The short bamboo fibre was chemically modified at an optimum condition by treating the fibre for 4 h using sodium hydroxide (2% w/v) to produce a sustainable bamboo fibre (BF)/polylactic acid (PLA) composite through injection moulding. The optimum injection conditions considered to develop BF/PLA composite were a melting temperature of 165 °C, injection speed of 60 mm/s, and injection pressure of 90 bars. The fibre length and loading of 4 mm and 20% were considered to fabricate the BF/PLA green composite. The developed BF/PLA composites were exposed to different environmental conditions like water, soil, refrigerator, and room temperature for four weeks. The fabricated BF/PLA green composite specimens were recycled five times by implementing the manual mechanical cutting process. The impact of various environmental conditions and recycling on the mechanical properties was systematically monitored. The morphology of the fractured recycled specimens and specimens exposed to different environmental conditions were also examined using a scanning electron microscope (SEM). The thermo gravimetric analysis (TGA) was performed on the recycled BF/PLA specimens to investigate the thermal degradation behaviour of the developed composites. The crystalline behaviour of the BF/PLA composite exposed to different environmental conditions and recycled samples was also analysed by using X-ray diffraction (XRD). The maximum water absorption and thickness of swelling of the developed composite were observed at 6.49% and 5.56% when compared to the dry BF/PLA specimens. The mechanical behaviour of the BF/PLA green composite was superior in room temperature conditions followed by refrigerating, soil burial, and water immersion conditions. The maximum degradation temperature of non-recycled and after the fifth recycled BF/PLA composite was perceived at 348 °C and 329 °C. The deterioration in PLA and BF was observed due to the thermo-mechanical recycling. The degree of crystallinity of the unexposed sample was observed as 57.75% with a semi-crystalline nature. The crystallinity of BF/PLA composite was changed to amorphous while exposed to water, soil, refrigerator, and room temperature with a degree of crystallinity of 9.41%, 18.62%, 31.62% and 37.93%. Meanwhile, the fifth recycled BF/PLA composite exhibited a degree of crystallinity of 12.71%.