Biochar as an efficient reinforcing agent for poly(lactic acid)/poly(ε-caprolactone) biodegradable composites with high robustness and thermo-resistance

Abstract

The brittleness of poly(lactic acid) (PLA) can be effectively mitigated by melt-blending it with poly(ε-caprolactone) (PCL). However, this approach compromises the vital strength and modulus of PLA, while the thermo-resistance remains low. In this regards, biochar (BC) was introduced to reinforce PLA/PCL composites as a modifier to improve mechanical and thermal performances. Herein, the effects of various contents of BC and annealing treatments were investigated on the properties of PLA/PCL composites. Interestingly, BC not only improved the mechanical properties of the composites but also reduced the semi-crystallization time by more than 70 %. Furthermore, annealing treatment increased the tensile strength and tensile modulus of the PLA/PCL/BC composites by 10.1 % and 6.3 %. Notably, Vicat softening temperatures of the composites with PLA to PCL proportions of 70:30 and 60:40 were increased to above 100°C. More importantly, the addition of BC effectively formed physical interaction with PLA, resulting in improvement in mechanical properties. Annealing treatment perfected the PLA crystal into a much more stable α-crystal form, resulting in an increase in thermal properties. This work paves an effective way to prepare PLA based biodegradable composites with high strength and thermo-resistance.