MISCIBILITY IN THERMOPLASTIC POLYURETHANE ELASTOMER POLY(STYRENE-CO-ACRYLONITRILE) BLENDS

Blends of a thermoplastic polyurethane (TPU) with poly(styrene-co-acry lonitrile) (SAN) were investigated by differential scanning calorimetr y (DSC) and dielectric spectroscopy. Blends were prepared by kneading. A shift of the glass transition temperatures (T-g) and specific heat increments (Delta C-p) at the T-g have shown that SAN dissolves more i n the TPU-rich phase than TPU in the SAN-rich phase. From dielectric m easurements it could be concluded that the relaxation processes in the TPU/SAN blends occur at the same temperatures as the relaxation proce sses in pure components, which suggests that the motions of TPU chains are decoupled from the motions of SAN chains. The addition of TPU to SAN copolymer causes a plasticizing effect at very low concentrations. Copyright (C) 1996 Elsevier Science Ltd