Improved properties of PLA biocomposites toughened with bamboo cellulose nanowhiskers through silane modification

Poly(lactic acid) (PLA) is a potential green alternative for conventional petroleum-based plastics. However, the brittleness limits its application (e.g., agricultural films, garbage bags, plastic bags, food containers, food packaging). In this study, silane-compatibilized (triethoxyvinylsilane, A-151) bamboo cellulose nanowhiskers (BCNW) were introduced into a PLA matrix to toughen the composites. The A-151 successfully grafted on the surface of cellulose, and the thermal degradation stability of BCNW decreased after A-151 modification. Morphological, tensile and thermal properties of the toughened PLA bionanocomposites were investigated, and the toughen mechanism was clarified. The silane linked BCNW and PLA via Si–O–C bonds and hydrogen bonds. Elongation at break of the composites remarkably increased from 12.3 ± 1.7% (untreated) to 213.8 ± 21.6% (16 wt% A-151 treated). Both tensile strength and modulus decreased with the silane treatment. Typical toughness fracture characteristic (wire-drawing) was observed on the fractural surface. Glass transition temperature and crystallinity decreased from 45.6 °C/30.33% (untreated) to 33.6 °C/13.23% (16 wt% A-151 treated).