Toughness Enhancement of Poly(lactic acid), Bamboo Particle and Ultrafine Bamboo-Char Ternary Biocomposites by Polyethylene Glycol Plasticization

In this study, polyethylene glycol (PEG) was introduced into PLA/BP/UFBC ternary biocomposites as a plasticizer to improve the toughness of the biocomposites. Mechanical and thermal properties of the modified biocomposites were characterized. The interface bonding characteristics between the matrix and additives were analyzed. The flexural strain of the biocomposites increased with the increase of PEG addition. The flexural strain of 6.79% was observed when the PEG addition was 10 wt%. The tensile modulus increased by 390.81 MPa with the addition of 6 wt% PEG. Fourier infrared spectroscopy (FTIR) analysis showed the presence of strong polar and hydrogen bonding interactions between the PLA and PEG. DSC analyses showed that melt-crystallization behavior occurred during the cooling process with the addition of 6 and 10 wt% PEG. Glass transition and cold crystallization of PEG- plasticized biocomposites were not observed. The decrease in melting temperature indicated that the crystallization rate was improved because of the PEG plasticization effect on PLA biocomposites. It proved that PEG can improved the homogeneous dispersion of BP and UFBC within PLA matrix along with their strong interfacial interaction. This work offers an innovative methodology for adjusting interfacial adhesion, and expanding the extensive applications of PLA.