CALCULATION OF CRYSTAL BIREFRINGENCE AND INFRARED DICHROISM IN POLYMERIC SAMPLES FROM X-RAY POLE FIGURE DATA.
MASSACHUSETTS UNIV AMHERST POLYMER RESEARCH INST
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In biaxially oriented polymer films, crystal orientation may be characterized by orientation functions evaluated from x-ray pole figure scans for various crystallographic planes. From such orientation functions, one may calculate the crystal contributions to birefringence and infrared dichroism. In addition, the relationships between orientation functions for various hkl planes are considered. The results are dependent upon the symmetry of the unit cell in the orthorhombic system, the orientation functions for any crystallographic plane may be calculated from experimental values for two planes, while in the hexagonal or tetragonal systems, data on one plane will suffice. Finally, a method for graphical plotting of orientation functions in triangular coordinates is presented. This method has two advantages a clear, simple visualization of the orientation functions is provided, for both uniaxial and biaxial orientation and the relationships between the orientation functions for different crystallographic planes may be expressed in terms of simple geometrical constructions. Author