Preparation and physical properties of poly(trimethylene terephthalate)/metallocene isotactic polypropylene conjugated fibers

Poly(trimethylene terephthalate) (PTT) and metallocene isotactic polypropylene (MIPP) polymers were extruded (in the proportions of 75/25, 50/50, 25/75) from two melt twin-screw extruders to prepare three PTT/MIPP conjugated fibers. This study investigated the preparation and physical properties of PTT/MIPP conjugated fibers using gel permeation chromatograph (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), potentiometer, a rheometer, the density gradient, wide-angle X-ray diffraction (WAXD), extension stress–strain measurement and scanning electron microscope (SEM). Melting behavior of PTT/MIPP polyblended polymers exhibited negative-deviation blends (NDB) and the 50/50 blend of PTT/MIPP showed a minimum value of the melt viscosity. Experimental results of the DSC indicated PTT and MIPP molecules formed immiscible system. The tenacity of PTT/MIPP conjugated fibers decreased initially and then increased as the MIPP content increased. Crystallinities and densities of PTT/MIPP conjugated fibers were the linear relation with the blend ratio. PTT and MIPP polymers were proved to be an incompatible system. On the morphological observation, it was revealed that the blends were in a dispersed phase structure. The pore/fiber morphology of a larger size from 0.5 to 3 μm in diameter was observed after 1,1,1,3,3,3-hexafluoro-2-propanol (PTT was removed)/paraffin oil (MIPP was removed) treatment on the cross-section of PTT/MIPP conjugated fiber. In this paper, PTT micro fibers were produced successfully.