Interfacial interaction improvement of polylactic acid/bamboo-char biocomposites for high toughness, good strength, and excellent thermal stability

In this paper, various contents of activated bamboo-char particles (ABC) (0–5 wt%) and polyethylene glycol (PEG) (0–15 wt%) were used to strengthen and toughen polylactic acid (PLA) through melt-blending and injection molding. The surface morphological, mechanical, thermal, and strengthening mechanism of the PLA/ABC biocomposites were investigated. The composites with 3 wt% ABC and 10 wt% PEG exhibited the optimal mechanical properties, with a modulus of 18.04 GPa, elongation at break of 105.6%, and impact strength of 3.28 KJ/m2. Compared to pure PLA, these values were increased by 283.8%, 5371.5%, and 105%, respectively. More importantly, tensile strength was comparable to that of pure PLA. Interestingly, PLA entered the pores of ABC under the plasticizing effect of PEG, forming a robust physical winding and interfacial interlocking structure resembling an "octopus-like" structure. Additionally, this structure was crucial for simultaneously enhancing toughness without compromising strength. These findings provide valuable methodological references to prepare structurally-functional integrated composite materials.