Exploring Mechanical, Thermal, Morphological and Rheological Properties of Polypropylene-Liquid Crystalline Polymer (Vectra-A950) Blends

摘要

Polypropylene (PP) was melt blended with VectraA950, a thermotropic liquid crystalline polymer (LCP) in different proportions in a single screw extruder. The mechanical properties of prepared PP-Vectra A 950 blends were compared in respect of their Young's moduli, ultimate tensile strength (UTS), percent elongation at break, toughness, hardness and impact strength to those of pure PP. Mechanical analysis (tensile properties) of the blends showed pronounced improvement in the moduli, UTS and hardness of PP matrix in the presence of 2-7% of LCP. The thermal properties of these blends were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC studies showed an initial drop of the melting point of PP in the PP-Vectra A 950 blend (2% LCP) followed by enhancement of the same in presence of higher proportions (7%) of LCP. TGA showed an increase in the thermal stability for all blends with respect to matrix polymer PP Morphological studies were performed by scanning electron microscope (SEM) which showed limited mixing and short fibrils with relatively more number of droplets observed in the lower amount of LCP containing blends. Towards the higher range of LCP concentration, thicker fibrils with sharp interfaces were developed. Rheological studies showed that Vectra A 950 dropped down the melt viscosity of PP hence facilitated processibility of the blends.