Preparation and Characterization of Polypropylene/Poly(L-lactic acid) Blend Fibers

Spin draw yarns (SDY) of polypropylene/poly(L-lactic acid) (PP/PLA) blends with various PLA contents were prepared using a commercial pilot spinning apparatus. Melt-quenched PP/PLA blend films were also prepared by melt-pressed the PP/PLA SDY fibers or PP/PLA blend chips at $200^{\circ}C$ and quenched in ice water. Thermal and mechanical properties of the PP/PLA blend fibers and films were analyzed by using a differential scanning calorimeter (DSC), a scanning electronic microscope (SEM), and a universal testing machine (UTM). Results showed that the melting temperature of the PP in the blends was unaffected by PLA blending and that PP and PLA crystallized independently. Although the melt-crystallization temperature increased slightly with increasing the PLA content in PP/PLA blends, the amount of PP crystal was not affected. PLA existed as beads in PP matrix, indicating that PP/PLA blends are immiscible. Tensile tenacity decreased and extension at break increased with increasing PLA content in PP/PLA SDY fibers.