Statistical thermodynamics of ABA block copolymers. III. Microstructural transitions and model verification

The predictions of a model presented previously are tested with data on five styrenebutadiene–styrene copolymers. Differential scanning calorimetry and laser light transmission are the primary tools, spanning 180–630°K, with some evidence supplied also by electron microscopy and mechanical properties. The existence of a first‐order phase transition, characterized by a separation temperatureTs, is verified and found to be predictable by the model. Details of morphology, including transitions in microstructure in certain temperature ranges, are also reported and shown to be consistent with the theory.