Visualization of shear stress in the sample
Mechanical material properties, as measured by rheological testing, strongly depend on microstructural changes under shear deformation and temperature conditions. Thus, the combination of optical techniques with rheological measurements is of high interest in the correlation of microstructural properties with the macroscopic behavior of the material. Different optical methods such as small-angle light scattering (SALS), microscopy (polarized light, fluorescence, confocal), spectroscopy (NIR, IR, Raman), birefringence, as well as pure visualization techniques can be employed.
Different to SALS, microscopy, or spectroscopy methods, polarized light imaging enables the observation of the complete sample area while sheared in the rheometer. The integrated behavior of macromolecules and nanoparticles can thus be detected.