Rheo‐optical studies of the deformation of crystalline polymers

The deformation of a polycrystalline polymer must be examined in terms of the changes in morphology, texture, crystalline structure, and chain conformation. The understanding of the dynamic mechanical properties requires the specification of the rates of these changes. Optical techniques may be employed for this purpose. Dynamic x‐ray and dynamic infrared dichroism diffraction serve to define the rate of crystal orientation. Dynamic light scattering characterizes changes in the crystalline superstructure while dynamic birefringence characterizes the total orientation of crystalline and amorphous regions. A direct measure of amorphous orientation rate may be attempted by introducing a dye or chromophoric group into the amorphous regions and measuring its dynamic dichroism. In general, each of these dynamic observables may be resolved into a real and imaginary part (in and out‐of‐phase with strain). The results of measurements of these along with dynamic modulus measurements are discussed in an effort to present a consistent molecular and structural interpretation of mechanical behavior.