DYNAMIC MECHANICAL-BEHAVIOR OF POLYSULFONES

The dynamic mechanical properties of a series of polysulfones made from a wide range of bisphenols have been analyzed. The structural variations include 0, 1, 2, or 3 methyl groups per phenyl ring and a wide range of groups connecting the phenyl rings in the bisphenol while the diphenyl sulfone unit was not changed. The symmetry and placement of these modifications and the resulting rigidity affect the T(g) and the sub-T(g) spectra. Both intramolecular and intermolecular factors contribute to these changes. For these polysulfones, the glass transitions ranged from 150 to 298-degrees-C and the sub-T(g) relaxation temperatures ranged from -100 to +200-degrees-C. Substitutions that directly hinder phenylene mobility increase the temperature at which the gamma-relaxation occurs. The appearance of more than one gamma-peak for some structures has been interpreted to mean that the extended intramolecular coupling of monomer units proposed for polycarbonates is apparently not a necessary component of the sub-T(g) relaxation in these polymers. Differences in the molecular motions of polysulfones and polycarbonates were briefly addressed by molecular modeling. A comparison of selected polysulfones and poly(ether ketones) shows that whatever contribution the sulfone unit makes to the sub-T(g) mechanical spectra, carbonyl units make a similar contribution. Intermolecular chain packing or free volume strongly affects the temperature location of the gamma-relaxation attributed to motions of diphenyl sulfone units.