Thermal and Mechanical Properties of Polyblends of Polycaprolactam with Cationic Dyeable Poly(ethylene terephthalate)

Abstract

One Polycaprolactam (PCPL) polymer and three cationic dyeable poly(ethylene terephthalate) (CD-PET) polymers were blended mechanically in the proportions of 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 in a melt twin-screw extruder to prepare twenty-seven PCPL/CD-PET polyblended polymers. The molar ratios of 5-sodium sulfonate dimethyl isophthalate (5-SSDMI) for three CD-PET polymers were 2, 6 and 10%, respectively. This study investigated the thermal and mechanical properties of PCPL/CD-PET polyblended materials using gel permeation chromatograph (GPC), nuclear magnetic resonance (NMR), gas chromatography (GC), potentiometer, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscope (SEM), extension stress-strain measurement, density gradient method and rheometer. Experimental results of the thermal properties indicated PCPL and CD-PET molecules easily formed individual domains. PCPL and CD-PET polymers were proved to be immiscible system even when CD-PET possessed higher 5-SSDMI content. Rheological behaviour of PCPL/CD-PET polyblends exhibited negative-deviation blends (NDB). The measurements of densities showed linear variation with the blend ratio of PCPL/CD-PET polyblends. The SEM pictures displayed the blend ratio of PCPL/CD-PET was 50/50, the morphological aggregation of a larger size from 3 to 5 μm in diameter was observed. Experimental results of the mechanical properties indicated the 50/50 blend of PCPL/CD-PET showed a minimum tensile strength.