Plasticizer effect of novel PBS ionomer in PLA/PBS ionomer blends

Abstract

Poly(lactic acid)(PLA) was blended with poly(butylene succinate)(PBS) and PBS ionomer (PBSi) at various compositions, and their compatibility and crystallization behavior were examined by dynamic mechanical analysis (DMA), tensile testing, scanning electron microscopy, differential scanning calorimetry, and polarized optical microscopy. The DMA data showed lower storage moduli with increasing PBS and PBSi content, and the tan δ peaks of the blends showed lower values than those of PLA. The tensile test results and fractured surface morphology indicated that PLA/PBSi blends have more flexible and compatible characteristics than the PLA/PBS blends. The interaction parameters calculated from the Flory-Huggins equation predicted that the PLA/PBSi blends have more compatible characteristics than the PLA/PBS blends. The Avrami exponent (n) and crystallization kinetics constant (K) were derived from isothermal crystallization experiments to predict the crystallization phenomenon of the blends. The use of PBS or PBS ionomer resulted in faster crystallization rates of the blends. From an observation of the overall crystallization rate and spherulite radial growth rate, it was concluded that the abundant ion groups increased the compatibility between the PLA and PBSi chains, and the PBSi molecules acted as a plasticizer in the PLA blends.