Cationic dyeable poly(ethylene terephthalate) (CD-PET) and metallocene isotactic polypropylene (m-iPP) polymers were extruded (in the proportions of 75/25, 50/50, 25/75) from two melt twin-screw extruders to prepare CD-PET/m-iPP (and m-iPP/CD-PET)-conjugated fibers of the island-in-sea type. This study investigated the thermal behavior and mechanical and morphological characteristics of the conjugated fibers using DSC, TGA, WAXD, melting viscosity rheometer, density indicator, tenacity measurement, and a polarizing microscope. Melting behavior of CD-PET/ m-iPP polyblencled polymers exhibited negative-deviation blends (NDB) and the 50/50 blend showed a minimum value of the melt viscosity. Experimental results of the DSC indicated CD-PET and m-iPP molecules formed a partial miscible system. The tenacity of CD-PET/m-iPP-conjugated fibers decreased initially and then increased as the m-iPP content increased. Crystallinities and densities of CD-PET/m-iPP-conjugated fibers presented a linear relation with the blend ratio. On the morphological observation, it was revealed that the blends were in a dispersed phase structure. In this study, the CD-PET microfibers were successfully produced with enhanced diameters (from 2.2 to 2.5 mu m). Additionally, m-iPP colored fibers (m-iPP fibers covered with CD-PET polymer) were also successfully prepared. Meanwhile, the presence of PP-graft-MA compatibilizer improved the tenacity considerably. Blends with 10 wt % compatibilizer exhibited maximum improvement in the tenacity for m-iPP colored fibers. The dye exhaustions of various fabrics followed the order: m-iPP colored fibers > conventional CD-PET fibers > CD-PET microfibers. (c) 2006 Wiley Periodicals, Inc.