Intrinsic Polymer Research Articles

Prediction of second virial coefficients from intrinsic viscosities

AbstractOne of the most readily available characteristics of a polymer sample is its intrinsic viscosity in a particular solvent. This datum can often be estimated reasonably from a single relative viscosity measurement. A number of theories permit the calculation of the second virial coefficient of a polymer/solvent mixture given the intrinsic viscosity and polymer molecular weight. The intrinsic viscosity of the polymer under theta conditions is also needed, but this can be estimated, if necessary, from the molecular weight. This article compares the efficiencies of various alternative models for the prediction of second virial coefficients of a series of polymers and solvents. The most effective technique for this purpose first calculates the concentration‐dependent equivalent hydrodynamic volume of a solvated polymer coil. This value is used with a primitive statistical mechanical theory for virial coefficients of hard‐sphere suspensions to calculate the osmotic pressure or turbidity of the polymer solution. These simulated experimental values are fitted with a least‐squares line as in the real experiment, and the second virial coefficient is derived from the slope. The computations are relatively simple; the average deviation between observed and predicted virial coefficient was less than 16% for a variety of polymer types, molecular weights, and solvents.

Polyvinyl chloroacetate

AbstractSeries of bulk and solution polymerizations of vinyl chloroacetate have shown that the properties of the polymer vary widely with variation in polymerization conditions. The highest viscosity polymer, intrinsic viscosity polymer, intrinsic viscosity of 1.32, is prepared by bulk polymerization with 0.028% benzoyl peroxide initiator at 70°C. At polymerization temperatures sdover 70°C. and at catalyst concentrations over 0.14%, the polymer is discolored, insoluble, or has relatively poor aging characteristics. Polymerization in an equal volume of methyl isobutyl ketone at 80°C. and with 0.013% benzoyl peroxide gave 93% yield of polymer of intrinsic viscosity 0.15. In nitrobenzene, toluence, trichloroethylene, or ethyl acetate, only traces of polymer are obtained. In carbon tetrachloride, unstable telomers are produced.