抄録
Anisotropy of the bridge fraction of middle isoprene block chains in sheared films of sphere-forming polystyrene-b-polyisoprene-b-polystyrene triblock copolymers in different directions are examined by breaking stress under simple elongation measurements at a fast draw rate, which reflect the bridge fraction. There was no practical difference between the data obtained for the films cut in the directions parallel and perpendicular to the shear flow direction at each shear rate. The breaking stress for the samples sheared at high shear rates become slightly lower than those obtained at low sher rates. The absolute values and the difference is consistent with the previous study, in which pull out of end blocks due to the flow is examined. Thus, we conclude that when flow is applied to sphere-forming triblocks, only small portion of end blocks are pulled out to flow and there is no orientation dependent anisotropy of bridge fractions.
