Enhanced Mechanical Performance of Bamboo Fiber/Polypropylene Composites via Micro-Nano Reinforcing Strategy

Developing high-performance plant fiber-reinforced thermoplastic polymer composites using environmentally friendly and cost-effective methods remains a significant challenge. In this study, we present a novel micro-nano strategy for producing robust short bamboo fibers (BFs) reinforced polypropylene (PP) composites (SBFPCs) without the need for chemical modification. Our approach involves the utilization of purified short micron BFs, which is surface-coated with holocellulose nanofibers (HNFs) extracted from bamboo parenchyma cells (BP). Through conventional injection processing, the resulting SBFPCs demonstrate remarkable mechanical enhancements with just a 0.2 wt% addition of HNFs compared to control samples. Notably, the mechanical properties of our SBFPCs surpass those of most reported short plant fiber-reinforced thermoplastic composites. The superior mechanical performance of our SBFPCs can be attributed to several factors, including the use of purified micron BFs with optimal aspect ratios as the primary reinforcement phase, enhanced interfacial mechanical interlocking between BFs and the PP matrix facilitated by the addition of HNFs, and the potential dispersion of HNFs within the PP matrix at submicron or nanoscale as a secondary reinforcement phase. This study highlights the promising application of SBFPCs in engineering areas with stringent mechanical requirements.