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Dynamic mechanical study of polycarbonate-based block copolymers



The dynamic-mechanical properties of some multi-ABA-type block copolymers were studied using the Rheovibron viscoelastometer. Records of tan δ, loss moduli, and storage moduli were obtained over the temperature range of −100°C to 200°C (or the upper glass transition temperature) for samples cast from different solvents. Separate glass transitions were apparent when there was phase separation. Under the test conditions, the soft segment or block formed the continuous phase and the associated glass transition was independent of the solvent used. The hard-segment phase was either continuous or discretely aggregated, depending on the solvent used. For hard segments from large monomer molecules, the discretely aggregated phase displayed a greater modulus. The reverse was true when the monomer molecules were small.

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