Thermal properties and mechanical characteristics of cationic dyeable poly(trimethylene terephthalate)/metallocene isotactic polypropylene conjugated filaments

Cationic dyeable poly(trimethylene terephthalate) (CD‐PTT) and metallocene isotactic polypropylene (m‐iPP) polymers were extruded (in proportions of 75/25, 50/50, and 25/75) from two melt twin‐screw extruders to prepare three CD‐PTT/m‐iPP conjugated filaments of the island–sea type. This study investigated the thermal properties and mechanical characteristics of the CD‐PTT/m‐iPP conjugated filaments with gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, potentiometry, rheometry, density gradients, wide‐angle X‐ray diffraction, extension stress–strain measurements, and scanning electron microscopy. The rheological behavior of the CD‐PTT/m‐iPP polyblended polymers exhibited negative‐deviation blends, and the 50/50 CD‐PTT/m‐iPP blend showed a minimum value of the melt viscosity. The experimental results from differential scanning calorimetry indicated that CD‐PTT and m‐iPP molecules formed an immiscible system. The tenacity of the CD‐PTT/m‐iPP conjugated filaments decreased initially and then increased as the m‐iPP content increased. Morphological observations revealed that the blends were in a dispersed phase structure. A pore/filament morphology of a larger size (0.5–3 μm in diameter) was observed after a 1,1,1,3,3,3‐hexafluoro‐2‐propanol (CD‐PTT was removed)/decalin (m‐iPP was removed) treatment in the cross section of a CD‐PTT/m‐iPP conjugated filament. The CD‐PTT and m‐iPP polymers were identified as an immiscible system. Blends with 10 wt % compatibilizer exhibited the maximum improvement in the tenacity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2387–2394, 2007