THE PROBLEM OF INTRINSIC BIREFRINGENCE AND CHAIN CONFORMATION IN POLYCARBONATE FROM BISPHENOL-A

The PC-monomer is found to be a good example for elucidating the problems engendered by more complex monomers when the orientation behavior is investigated. The discrepancies found in the literature regarding the intrinsic birefringence can be fully resolved with the following assumptions: The carbonyl-unit is neither in the trans nor in the cis configuration, and the absorption band at 1364 cm-1 is a mixture of in-phase and out-of-phase symmetric bending vibrations of the isopropyl methyl-groups. Planar and helical chain conformations are found which are thought to build up the amorphous phase. It is demonstrated that the crystal structure as known from literature can be realized by the planar conformations. © 1990 Steinkopff.