Evaluation of parameter uncertainties during the determination of the intrinsic viscosity of polymer solutions

In this work, it is shown that quadratic approximations of the function tha t relates the viscosity of polymer solutions with the polymer concentration lead to values of the intrinsic viscosity that are much more uncertain tha n the values obtained through simpler linear fits. Therefore, in spite of t he expected better interpolations provided by second-order approximations, statistical arguments show that the use of linear fits is advisable when th e number of experimental points available for the determination of intrinsi c viscosities is small. Experimental data available for solutions of poly(4 ,4/-diphenylether-1,3,4-oxadiazole)s, POD-DPE, in sulfuric acid are used to illustrate this point. (C) 2000 Elsevier Science Ltd. All rights reserved.