Plasticization of polylactide with block copolymers of ethylene glycol and propylene glycol

In this study, plasticization of polylactide (PLA) with PEGPPGPEG triblock copolymers was examined. Two different copolymers were utilized, with molecular weight of 1100 and 1900 g mol(-1), and with PEG contents of 10 and 50 wt %, respectively. A PPG plasticizer with molecular weight of 1000 g mol-1, close to that of PPG block in the copolymers, was also used for comparison. Melt blends containing 10 and 15 wt % of the plasticizers were prepared. Thermal properties, mechanical properties, and structure of quenched and annealed films of the blends were studied. The crystallization driven phase separation occurred in all the annealed blends but led to different structures depending on the plasticizer used. Distinct inclusions of the plasticizer were visible under the scanning electron microscope only in PLA with PPG but not in the blends of PLA with the copolymers. The drawability of the plasticized systems was improved when compared with neat PLA. In the quenched and annealed blends, elongations at break at the level of 5 and 0.7, respectively, were reached. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012