Studies on mechanical, thermal, rheological and impact properties of polyamide 6 and thermoplastic copoly(ether-ester) elastomer blends

A series of blends of polyamide 6 (PA-6) (nylon-6) and a copoly(ether-ester) (HYTREL) were prepared by the melt-mixing method using a twin-screw extruder. The HYTREL content was varied from 0% to 25% by weight of the blends. Thermal and rheological studies on the blends using differential scanning calorimetry, dynamic mechanical analysis (DMA) and capillary rheometer showed that the blends are semi-compatible in nature. A two-phase globular morphology of the blends was established by scanning electron microscope (SEM) analysis. The matrix ligament thickness (interparticle distance) in each blend composition was measured from SEM images and compared with those calculated using Wu's equation. The impact strength of the blends as measured by the Izod impact test was found to be substantially improved as a result of the incorporation of HYTREL. The toughness determined by loss area calculation from the DMA spectrum showed similar trends. The toughness was found to be optimal in a blend having 15 wt.% HYTREL with an average dispersed particle size of around 450 nm. The yield stress of the blend decreased in comparison to PA-6 on addition of HYTREL, while the thermal stability of PA-6 remained unaffected.