Pyrolysis kinetics and mechanical properties of poly(lactic acid)/bamboo particle biocomposites: Effect of particle size distribution

Abstract

Bamboo particle (BP)-reinforced poly(lactic acid) (PLA) biocomposites were fabricated. The effect of the BP particle size distribution on the pyrolysis and mechanical properties of PLA biocomposites was evaluated. The optimum particle size of BP for improving the tensile strength PLA biocomposites is 200 mesh (16.6-84.5 μm). The pyrolysis mechanism and kinetics were studied according to the Coats-Redfern method. The addition of BP inhibited the pyrolysis process of PLA. The activation energy of biocomposites ranged from 120.7 to 151.5 kJ/mol, which is significantly higher than that of the neat PLA. The pyrolysis mechanisms of biocomposites are attributed to the chemical reaction at low pyrolysis temperature (270-400℃) and ash layer diffusion control at high pyrolysis temperature (400-600℃). Crystallization behavior of biocomposites showed that small BPs in PLA biocomposites generated more cross-linking points in the PLA matrix, which constrained the movement of the molecular chain and acted as an effective nucleating agent in promoting the crystallization process. The pyrolysis behavior and mechanical properties analysis provide critical information for potential large-scale production of the PLA biocomposites.