Effects of the chain-extender content on the structure and performance of poly(lactic acid)-poly(butylene succinate)-microcrystalline cellulose composites

Composites of poly(lactic acid) (PLA) with poly(butylene succinate) (PBS) and microcrystalline cellulose (MCC) as reinforcements of the polymer matrix were prepared by melt blending to improve the brittleness of PLA. As a reactive compatibilizer, a chain extender was used in an attempt to solve the composites' interfacial problems and to improve their mechanical properties; Fourier transform infrared spectroscopy indicated that the chain extender functionally reacted with PLA, PBS, and MCC mainly through end carboxyls or end hydroxyls. Scanning electron microscopy indicated that the chain extender significantly improved the cohesive interfacial forces. Differential scanning calorimetry and X-ray diffraction showed that the chain extender inhibited crystallization, and these effects were greater when its percentage was increased. The addition of chain extender improved the tensile and impact strength of the composites, and this improvement was proportional to the chain-extender percentage. However, the elongation at break decreased when the chain-extender percentage was over 0.5% because of mild crosslinking within the resin matrix. Rheology indicated that the complex viscosity and storage and loss moduli of the composites increased with increasing amount of chain extender; this indicated that the addition of chain extender improved the melt strength and processability of the composites. (C) 2017 Wiley Periodicals, Inc. J. Appl. Polym.