Preparation and characterization of polylactide/poly(polyethylene glycol-co-citric acid) blends

The blends of polylactide (PLA) and poly(polyethylene glycol-co-citric acid) (PEGCA) were prepared by melt mixing in an internal mixer. The effects of PEGCA content on the processibility, morphological, thermal, mechanical properties as well as hydrophilicity of PLA/PEGCA blends are investigated by rheometer, scanning electron microscopy, differential scanning calorimetry, mechanical testing, and water contact measurements. During thermal processing, the presence of PEGCA delayed the melting of PLA and lowered the viscosities of the blends. PLA/PEGCA blends exhibited a phase-separated morphology. The sizes of the dispersed phase increased with increased PEGCA content. The glass transition temperature of PLA decreased with the addition of PEGCA. The crystallization behaviors of PLA and PEGCA in their blends were influenced by each other. Ductility and toughness of PLA were significantly improved by the presence of PEGCA. PEGCA also greatly improved the hydrophilicity of PLA significantly.