AbstractThe concentration dependence of viscosities of dilute solutions of nonpolar polymers can be expressed generally as power series in concentration. Intrinsic viscosity is often estimated from zero concentration extrapolations of the Huggins and Kraemer equations, which are truncated versions of virial expressions in concentration. Neither form is strictly valid at most practical concentrations since real curvilinear relationships are forced into rectilinear forms. Prior methods of overcoming this deficiency by basing extrapolation methods for η on more extended power series have attempted to provide graphically useful solutions. This requires reduction of the power series to a two‐parameter (slope and intercept) form and the assumption of certain relations between the various factors in the initial multiparameter expression. In this work, power series expressions in concentration are solved directly by nonlinear regression analysis. It is shown that no two‐parameter solution is generally valid, although each may be of value in a particular context. Three‐parameter power series extensions of the basic Huggins and Kraemer equations represent dilute solution viscosities up to concentrations of 1 or 2 (w/v) very well. The computer‐assisted nonlinear regression analysis is easily extended to higher powers of concentration, and the use of four‐parameter forms is illustrated to represent viscosities of polystyrene solutions with concentrations as
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