Elongation of Block Copolymer Melt: Elongation Flow Opto-Rheometry and Small Angle X-ray Scattering Study

초록

The elongational flow-induced alignment process of diblock and triblock copolymers has been investigated by using elongational flow opto-rheometry (EFOR) and small angle X-ray scattering (SAXS). The ordered domains of the compression molded SEP polymers were aligned in a preferred direction by roll-casting at 200 oC. In the EFOR measurement, the roll-cast films are uniaxially elongated at 180 oC at a Hencky strain rate, , of 0.01 sec-1 in the direction either perpendicular (denotes case 1) or parallel (case 2) to the direction of the lamellar normals. The apparent retardation, Rapp, and initial moduli data measured during elongation suggest that either the mechanically hard domain or the soft domain is preferentially elongated during the early stage of elongation. Transient elongational viscosity, , measured during the case 1 elongation exhibits a continuous increase up to rupture with the absence of the morphological change.