Morphological, Mechanical, and Crystallization Behavior of Polylactide/Polycaprolactone Blends Compatibilized by L-Lactide/Caprolactone Copolymer

L-Lactide/caprolactone copolymer (LACL) was employed as a compatibilizer in the immiscible blends of polylactide (PLA) and polycaprolactone (PCL). Films of neat PLA, PLA/PCL blend, and PLA/PCL/LACL blends were prepared by solution casting and conditioning compression. The effects of LACL on the morphology, mechanical properties, and crystallization behaviors of the blends were investigated. The addition of LACL decreased the dimensions of the dispersed PCL domains in the ternary blends. The ultimate strain of the blend with 5% LACL was significantly improved and was accompanied by a small drop in tensile strength and modulus. Both the nonisothermal and isothermal cold crystallization of PLA were enhanced by PCL, and further improved by incorporating LACL. Polarized optical microscopy observation showed that the size of crystals decreased with the addition of PCL and LACL.