The amorphous state of bisphenol-A polycarbonate was examined by time-domain dielectric spectroscopy as a function of crystallization time over a frequency range of 1 x 10-4 Hz to 1 x 104 Hz. The dielectric measurements were performed in the temperature range around the glass transition temperature. Dielectric studies were performed on a series of samples, which were partially melted and recrystallized so as to investigate the influence of secondary crystallinity on the alpha relaxation, thereby probing the effect of crystalline constraints on cooperative motions in the amorphous fraction. Analysis of the relaxation behavior was performed by fitting the loss max frequency data to the Vogel-Fulcher-Hesse-Tammann and Arrhenius equations. Fits to the Havriliak-Negami equation were performed with careful consideration of the conclusions made by two of us in a recent paper: C.R. Snyder and F.I. Mopsik, J. Appl. Phys., 84 (8), 4421 (1998).
Citation: ASC Technical Conference
Pub Type: Journals
amorphous phase, bisphenol-A polycarbonate, dielectric spectroscopy, polymers, semicrystalline polycarbonate, time-domain dielectric spectroscopy