Abstract
Polycaproamide (PCA) polymer and cationic dyeable polycaproamide (CD‐PCA) polymer were blended mechanically in the proportions of 75/25, 50/50, and 25/75 in a melt twin‐screw extruder to prepare three PCA/CD‐PCA polyblended polymers. Blends of PCA and CD‐PCA were spun into filaments. The molar ratio of 5‐sodium sulfonate dimethyl isophthalate (5‐SSDMI) for CD‐PCA polymer was 1.99%. This study investigated the physical properties of PCA/CD‐PCA polyblended filaments using gel permeation chromatograph (GPC), nuclear magnetic resonance (NMR), gas chromatography (GC), potentiometer, thermogravimetric analysis (TGA), a rheometer, differential scanning calorimetry (DSC), the density gradient method, wide‐angle X‐ray diffraction (WAXD), extension stress‐strain measurement, and scanning electron microscope (SEM). Flow behavior of PCA/CD‐PCA polyblends exhibited positive‐deviation blends (PDB), and the 50/50 blend of PCA/CD‐PCA showed a maximum value of the melt viscosity. Experimental results of the DSC indicated PCA and CD‐PCA molecules easily formed miscible domains. The crystallinities of PCA/CD‐PCA polyblended filaments decreased as the 5‐SSDMI content increased. Tenacities/densities of PCA/CD‐PCA polyblended filaments were also found to decline as the 5‐SSDMI content increased. The surface of PCA/CD‐PCA polyblended filament exhibited a uniform morphology from the SEM data. PCA and CD‐PCA polymers were proved to be a compatible system. The weight loss percentages of the PCA/CD‐PCA polyblended filaments increased as the 5‐SSDMI content increased in aqueous NaOH solution. The porous morphology of a larger size from 0.01 to 2 μm in diameter was observed after alkali treatment of PCA/CD‐PCA polyblended filament. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1220–1226, 2005