Effect of Structure on Physical Properties of Polymers.

The effect of stereochemical configuration in poly-alpha-chloroacrylic acid esters was studied principally with respect to the glass and other transitional properties. A substantial dependence of glass transition temperature on tacticity as theoretically predicted was found. The interaction of small molecules, principally water, with a series of segmented polyurethanes of systematically varied structure was investigated by transport, sorption and calorimetric measurements. Analysis in terms of bound water models revealed cogent evidence for the amorphous nature of the adsorbate. A very sensitive measure of the effect of structure was found in a series of polymer miscibility studies on several chemically related binary systems which included poly2,6-dimethyl phenylene oxide PPO-polystyrene PS. Thermodynamic, electrical, and mechanical properties of compatible and near-compatible systems were investigated in detail. Mechanical properties of solid polymers such as polymethyl solid polymers methacrylate under hydrostatic pressure were determined principally with respect to the transitional behavior of the amorphous phase. The effect of pressure on the equilibrium properties of the crystalline phase high density polyethylene was studied in a concomitant wide angle X-ray diffraction experiment. In a second dynamical mechanical study, compound flexural vibrations in thick beams of polymethyl methacrylate were measured and analyzed. It was shown that the contributions of shear and elongational deformations could be resolved thereby providing a complete isotropic elastic characterization of materials in such configurations.