POLYMER STRUCTURES AND PROPERTIES
CARNEGIE-MELLON UNIV PITTSBURGH PA MELLON INST OF SCIENCE
Pagination or Media Count:
Theoretical studies of the properties of polymers in dilute solution have involved the effect of heterogeneity in molecular weight on the second virial coefficient the relation of chain dimensions to the virial coefficient and the effect of chain branching for the case of the star molecule with an arbitrary number of branches upon both dimensions and virial coefficients in poor solvents. Experimental results on the effects of branching are reported for polystyrene trifunctional molecules in both good and poor solvents. Linear polystyrene has been used in studying specific solvent effects on chain dimensions in media exhibiting very similar values for the Flory temperature. Some refinements have been made in the design of a light scattering photometer, and calibration procedures for establishing the absolute magnitude of Rayleigh scattering have been critically evaluated. The melt viscosities of mixtures of polymer fractions of very different. molecular weights appear to depend on the viscosity average molecular weight in a theta solvent rather than a higher molecular weight average, as has been suggested. New characterization data have been obtained for the vinyl acetate polymer obtained by emulsion polymerization in the presence of protein and detergent. From measurements of swelling of crosslinked polyethylene in solvents of different structure, it is concluded that specific solvent effects on chain dimensions are inappreciable for this polymer.
- Polymer Chemistry