Investigation of the thermal, mechanical, electrical and morphological properties of supercritical carbon dioxide assisted extrusion of microphase-separated poly(styrene-ethylene/butylene-styrene)

Abstract

This study investigates the effect of supercritical fluid carbon dioxide (scCO2) assisted extrusion on the thermal, mechanical, electrical, and morphological properties of microphase separated Poly(styrene-ethylene/butylene-styrene) [SEBS] triblock at various critical pressures. Thermal degradation analysis reveals 50°C enhancement in thermal stability of SEBS when extruded with scCO2 compared to SEBS extruded without scCO2. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) show improved phase separation due to the breakdown of domain size between the hard and soft block and damping losses represented by tan delta. It was found that SEBS processed with scCO2 has low elastic modulus because of foaming as well as restructuring of hard phase around the soft component. Fourier Transform Infrared Spectroscopy (FTIR) shows the interaction of scCO2 in aromatic phenyl rings of S-rich domain in SEBS. Dielectric spectroscopy analysis also confirms scCO2 results in the difference in relaxation of soft and hard blocks within triblock.