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Zusammenfassung:
The alignment kinetics for the orientation/reorientation behavior of the microphase of a lamellar PS-b-PI diblock copolymer under large amplitude oscillatory shear (LAOS) at a shear frequency ω1/2π is studied. This blockpolymer serves as a model compound for complex morphologies and textures. The degree of mechanical nonlinearity was online monitored via the intensity of the mechanical higher harmonic response at 3ω1 during the orientation nd reorientation process (FT-Rheology). FT-Rheology was combined with an quantification of the orientation using 2-dimensional small angle X-ray scattering (2D-SAXS). Within this study the kinetics of the change in macrophase alignment from the parallel to the perpendicular orientation is induced by applying two different oscillatory shear conditions. Improved parallel alignment after increasing the shear frequency as well as spatial heterogeneous alignment kinetics are detected. Thus, FT-Rheology offers a new and simple way for online monitoring for orientation kinetics in complex materials e.g. in foods.
