Fabrication and Characterization of Isotactic Polypropylene (iPP) Nanofibers from Immiscible Blends with Polylactic Acid (PLA)

In this article, binary blends of polylactic acid (PLA) and isotactic polypropylene (iPP) were prepared via melt blending in a co-rotating twin-screw extruder. Miscibility, thermal properties and crystallization behaviors of PLA/iPP blends were investigated using dynamic mechanical analysis (DMA), differential scanning calorimeter (DSC), and wide angle X-ray diffraction (WXRD). As observed from the tan delta curves in DMA and the glass transition temperatures in DSC, experimental results indicated that the blends were thermodynamically immiscible. Moreover, the iPP microfibrils were prepared from PLA/iPP immiscible blends and subsequent extraction removal of PLA matrix. The effects of PLA/iPP blend ratio and melt viscosity on the microfibrillar morphology of iPP nanofibers were analyzed using scanning electron microscope (SEM) and dynamical rheometer. The elasticity ratio was proposed to play an important role together with the viscosity on the phase morphology because PLA/iPP blends presented a high viscosity ratio between two components.