Molecular weight distribution in a poly(vinyl chloride–vinyl acetate) copolymer

Abstract

synopsisThe molecular weight distribution of a' vinyl chloride-vinyl acetate copolymer has been studied by three methods: (a) solution fractionation; (b) osmometry and light scat>tering; (c) gel permeation chromatography. In (a), the fractions were precipitakd from a tetrahydrofuran solution by water, then characterized. The data yielded models for the intrinsic viscosity and the molecular weight distribution, in terms of the copolymer molecular weight. In (b), the unfractionated copoIymer was characterized by osmometry and light scattering, using in the latter case the two currently accepted theories for the determination of the true weight-average molecular weight. Conflicting data suggest caution in the use of these theories. In (c), the original fractions served to establish a calibration curve which yielded exceptionally low results when applied to the analysis of the unfractionated VC-VAc copolymer. Further investigations using proposed universal calibration theories bring to light serious discrepancies.

Gel permeation chromatography in the study of the molecular weight distribution vinyl chloride–vinyl acetate copolymer. III. Influence of the incompatibility of polymers and some problems of interpretation of experimental data

“…Of course, none of the investigated fractions of various commercial VC-VAc copolymers can be defined from this standpoint. The straight line plotted by the method of linear regression through the experimental points of all three papers in Figure 2 (with the exclusion of the above exceptions) is described by (4) The regression coefficient for the set of treated experimental data was r = 0.993.…”