DYNAMIC MECHANICAL-BEHAVIOR OF POLYSTYRENE-(ETHENE-CO-BUTENE)-POLYSTYRENE, TRIBLOCK COPOLYMER FILMS CAST FROM VARIOUS SOLVENTS

Films of Kraton G-1650, a styrene-(ethene-co-butene)-styrene triblock copolymer, have been cast from a variety of solvents with solubility parameters in the range 15.1 to 20.5 (J m-3)1/2. The complex modulus E*, measured at 298 K, was found to vary from 4.4 × 106 N m-2 for films cast from low δ solvents to 2.05 × 108 N m-2 for films cast from high δ solvents. The areas under the damping peaks in the dynamic mechanical spectra were also altered by the casting solvent, which influences the manner in which the two component blocks are distributed in the solid state. Evidence of limited crystallinity in Kraton-G was found using differential scanning calorimetry and this was also used to estimate the heat capacity changes ΔCP for the glass transitions associated with each block. These were always found to be less than that expected for the pure component. © 1979, American Chemical Society. All rights reserved.