synopsisPoly-4,4'-oxydiphenylenesulfonyl and poly-4,4'-methylenediphenylenesulfonyl were synthesized by an electrophilic substitution polymerization of the arylene monosulfonyl chloride monomers. The glass-transition temperatures T, of these polymers were determined by calorimetric and dynamic mechanical measurements, and the number-average molecular weights were determined by vapor-pressure osmometry. Both polymers were found to have the same T, at equivalent molecular weight; the limiting value a t high molecular weight is 238°C. Both polymers have two dynamic mechanical relaxation peaks at temperatures far below T,. One is in the neighborhood of O"C, and the other is at -110°C. Plausible origins for these relaxations, and the absence of any near 0°C in poly(4,4'-isopropylidenediphenylen~,4'-~~1lfony~diphenylene dioxide), are discussed. 14. J. M. Barrales-Rienda and D. C. Pepper, J . Polym. Sci. B, 4,939 (1966). riam, J . Po/ym. Sci. A-1, 5 , 2378 (1967).

High‐pressure ethylene–vinyl acetate copolymers of four different chemical compositions(9%, 15%, 45%, and 70% VA) were characterized to determine molecular weight and distribution. The four samples were fractionated by solvent–nonsolvent precipitation methods. Light‐scattering, osmometry, and viscosity measurements were made on these fractionated copolymers to determine weight‐average molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {M_w } $\end{document}, number‐average molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {M_n } $\end{document}, molecular size in solution, and interaction constants. Dilute solution viscosity was measured on the fractions to determine intrinsic viscosity and Huggins' constant k′. Viscosity–molecular weight equations were established for the four copolymer compositions. The log intrinsic viscosity versus log molecular weight diagrams were analyzed and the average length of branches calculated. The composition of the polymer fractions, determined by C and H combustion analysis, was found not to vary significantly with molecular weight. The uniformly random character of the E/VA copolymers was thereby confirmed. The density of the fractions was determined by density‐gradient column method. Chain sequence distribution of monomer units for the four copolymers was calculated by using IBM 704 computations involving the actual monomer reactivity ratios. Long sequences of either ethylene or vinyl acetate are improbable, except at the extremes of copolymer composition.