Effect of crystallization on microstructure and mechanical properties of poly[(ethylene oxide)-block-(amide-12)]-toughened poly(lactic acid) blend

The effect of crystallization on the microstructure and mechanical properties of a poly[(ethylene oxide)-block-(amide-12)] (PEBA)-toughened poly(lactic acid) (PLA) blend was investigated. Annealing was used to govern the crystallization microstructure and hence the mechanical properties of the blend. Crystallization resulted in the morphology of the PLA component altering from a continuous amorphous phase to continuous crystalline phase. Moreover, as the crystallization of PLA proceeded, the degree of crystallinity, spherulite size and lamellar thickness increased, and the interlamellar and interspherulitic connections became weaker. These led to the large plastic deformation in the matrix during tension being suppressed, and cracks appeared easily under tensile load, which was favorable to fracture for the blend during tension and so a small elongation at break was obtained. However, the elongation at break for all the annealed specimens was higher than that for neat amorphous PLA, suggesting that PEBA still showed a toughening effect for PLA under annealing. (C) 2012 Society of Chemical Industry