The effects of plasticizers on the dynamic mechanical and thermal properties of poly(lactic acid)

Poly(lactic acid) (PLA) was blended with five plasticizers in a batchwise mixer and pressed into films. The films were analyzed by means of dynamic mechanical analysis and differential scanning calorimetry to investigate the properties of the blends. Triacetine and tributyl citrate proved to be effective as plasticizers when blended with PLA. The glass transition temperature of PLA decreased linearly as the plasticizer content was increased. Both plasticizers were miscible with PLA to an extent of similar to 25 wt %. At this point, the PLA seemed to be saturated with plasticizer and the blends tended to phase separate when more plasticizer was added. There were also signs of phase separation occurring in samples heated at 35, 50, and 80degreesC, most likely because of the material undergoing crystallization. The presence of the plasticizers induced an increased crystallinity by enhancing the molecular mobility. (C) 2002 Wiley Periodicals, Inc.