Abstract
A combination of infrared (IR) analysis with gel-permeation chromatography (GPC) has permitted the determination of both the molecular-weight distribution and the composition of a vinyl—vinyl acetate copolymer as a function of molecular weight. A sample of the copolymer was fractionated by repeated injection into an analytical scale GPC. Copolymer films made from the fractions were then subjected to IR analysis for the determination of the vinyl acetate content. The latter was high at low molecular weight and decreased with increasing molecular weight. Q factors for the copolymer at each increment of elution volume have been calculated from the Mark—Houwink equations for polyvinyl chloride, polyvinyl acetate and polystyrene and from the vinyl acetate of the copolymer. Molecular-weight averages of the copolymer have been calculated using a polystyrene calibration curve and the Q factors for the copolymer which are a function of elution volume and vinyl acetate content. The values calculated by this method are in good agreement with those measured by other workers.
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