Microstructure and rheological properties of triblock copolymers under extrusion conditions

Triblock copolymers with different microstructures were subjected to macroscopic deformations under extrusion using a miniaturized high pressure capillary rheometer. The rheological properties of the triblock copolymers investigated depend strongly on composition and configuration of the building units, which are microphase separated into complex morphologies, Under extrusion conditions they organize to stretched layer systems, which are perpendicular oriented in respect to the direction of the shear plane and the orientation decreases again at high shear rates. The macroscopic order leads to integral values of the order parameter from two-dimensional small X-ray scattering and form birefringence, which show a good correlation in the relevant shear rate range. Furthermore, a master curve of the form birefringence can be obtained.