Measurement of the rheological properties of thermoplastic elastomers

Abstract

Abstract Using the Han slit/capillary rheometer, measurements were taken of the rheological properties of commercially available thermoplastic elastomers, namely, styrene–butadiene–styrene (SBS) block copolymer (Shell, Kraton), ethylene–propylene copolymer (Exxon, Vista), olefinic‐type thermoplastic rubbers (UniRoyal, TPR 1600, TPR 1900, and TPR 2800), and urethane thermoplastic elastomers (UniRoyal, Roylar A863 and Roylar E9). The rheological properties determined were shear viscosity and first normal stress difference at various melt temperatures. Depending on the material and the melt temperature tested, the range of shear rates tested was 50 to 700 sec −1 , and the range of shear stresses tested was 10 5 to 10 6 dyn/cm 2 . For comparison purposes, rheological measurements were also taken for a few materials using the Weissenberg rheogoniometer although its use was limited to low shear rates (or shear stresses). It was demonstrated clearly that the Han slit/capillary rheometer is a unique instrument for determining the rheological properties of thermoplastic elastomers in the range of high shear rates (or high shear stresses) often encountered in various polymer processing operations.