Green analytical methods for determination of intrinsic viscosity of hydroxyl terminated polybutadiene

In this work,determination of intrinsic viscosity,[h],of htpb polymers (synthesized by free radical as well as anionic polymerization) was carried out by single point methods which are environmental benign as they use relatively less solvent than the classical methods. five different methods were studied to select the best one for fast and accurate determination of [h] of htpb for routine quality control application. the polymer-solvent interaction parameter (χ) in three different solvents,i.e. toluene,tetrahydrofuran,and chloroform,was evaluated to select the suitable solvent for this study. two approaches,i.e. hoftyzer-van krevelen and hoy,were used for estimation of solubility parameter (dhtpb) of the polymers. the dhtpb obtained by hoftyzer-van krevelen method was found to deviate slightly from hoy's method. the average value of dhtpb was 17.25 and 16.77 mpa1/2 for free radical and anionic-htpb respectively. the δδ value (difference between solubility parameters of polymer and solvent) was in the order: toluene < chloroform < tetrahydrofuran. the χ value in toluene was the lowest (i.e. 0.38) indicating good solvation of the polymer. the results of [h] in toluene at 30 ±0.1 °c obtained by single point methods were compared with the value obtained by graphical extrapolation methods based on huggins,kraemer,martin,and schulz-blaschke equations. the huggins constant (kh) was <0.4 for both the polymers. the single point method based on kuwahara was found to be the best alternative to the graphical extrapolation methods with a deviation of ± 0.1 % from the value obtained by huggins method.the proposed method would save approximately 80 % solvent used as well as labour and time. thus,it is the most economical and environmental benign method for determination of intrinsic viscosity of htpb polymer.