Thermoplastic elastomers (TPEs) are highly coveted, because they possess the properties of thermoset rubbers but can be processed like thermoplastics. Foaming will enhance their sustainability by lowering material consumption. SEBS is a commercially important TPE. SEBS is seldom used as a neat polymer, because of inferior mechanical properties. One way of enhancing the mechanical properties of SEBS is by blending it with a homopolymer. In this work, the properties and foamability of SEBS/ PS blends have been studied. SEBS and its blends (SEBS-10PS, SEBS-30PS and SEBS-50PS) containing 10%, 30% and 50 wt% PS were compounded and moulded for further studies. SEM studies revealed that a portion of the added PS increased the size of the styrene domains of SEBS, while the remaining portion got phase separated as seen earlier [1,2]. In SEBS-30PS and SEBS-50PS, the phase separated PS was in the form of fibrils aligned in the flow direction, leading to a significant enhancement of tensile modulus. All blends showed a negative deviation of melt viscosity from the additive rule of mixtures, attributed to the facilitation of slippage of SEBS by the low viscosity PS. When foamed with carbon dioxide at a higher foaming temperature (100 °C), SEBS-30PS and SEBS-50PS produced stable foams of higher volume expansion ratio, attributed to higher values of complex viscosity and storage modulus. Foams of SEBS and SEBS-10PS shrank. At a much lower foaming temperature (35 ⁰C), PS showed a nucleating effect. However, all foams shrank. A higher PS content led to a more prominent shrinkage, attributed to the selective foaming of the elastomeric phase, hindered by the stiff PS aggregates [3]. Thus, SEBS/PS blends of a higher PS content have superior mechanical properties, enhanced flow at higher shear rates and superior foamability at higher foaming temperatures, as compared to blends of lower PS content. References [1] Raha, S; Kao, N; Bhattacharya, SN. Polymer Engineering & Science, 52(2012); [2] Sharudin, R; Ohshima M. Journal of Applied Polymer Science, 128(2013); 2245 [3] Banerjee, R; Ray, SS; Ghosh AK. Journal of Cellular Plastics, doi: 10.1177/0021955X16652108