EFFECT OF ORIENTATION ON THE RELATIVE DISPERSION OF PMDA-ODA POLYIMIDE AND POLYPROPYLENE

The relative dispersion of birefringence, D-b, is determined for isota ctic polypropylene and Kapton HA PMDA-ODA polyimide films. D-b is then used to identify the dependence of dispersion on the orientation of p olymers and is interpreted in terms of fringe jumping. Optical relatio nships between the in-plane birefringence and wavelength are formulate d to predict the in-plane birefringence of oriented Kapton HA PMDA-ODA polyimide films at any wavelength. These relations can be used for th e direct comparison of the in-plane birefringence of Kapton PMDA-ODA p olyimide films obtained from different optical techniques (i.e., polar ized microscopy, polarized refractometry, wave guide coupling, etc.). (C) 1995 John Wiley and Sons, Inc.