SOLUTE ADSORPTION AND SHEAR FIELD EFFECTS IN THE CHROMATOGRAPHIC ANALYSIS OF HIGH MOLECULAR WEIGHT POLYMERS.

摘要

In this study some non-conventional methods of polymer separation were evaluated. Adsorptive mode gel permeation chromatography (GPC) using cyclohexane eluent and Styragel packing was shown to retain polystyrene according to molecular weight within the range of 2 x 10('4) to 1 x 10('6) MW, the highest molecular weight sample being most strongly retained. The effects of temperature in a theta solvent and of solvent power on adsorption were studied. Adsorption increased as temperature and solvent power decreased.; Thin layer chromatography (TLC) was used to separate samples of cis-polyisoprene according to molecular weight within the range of 10('3) to 10('6) in a simple, rapid procedure. A method for the field analysis of chicle by TLC was developed which could easily be used in a field situation for other polyisoprene-containing plants.; In the last part of this study, shear degradation of polymers in the GPC was examined for random coil and for semi-rigid rod polymers. It was found that shear degradation was related to the shape factor of a molecule at a given molecular weight. The semi-rigid rod conformation does not shear degrade in the GPC under the conditions studied in this research. For these molecules, the dependence of the peak elution volume (PEV) on sample concentration increases linearly with the hydrodynamic volume of the molecule. Random coil polymers which deviate from this linearity in the high molecular weight ranges, have been shown to shear degrade in the GPC. Thus, the deviation from linearity in the dependence of the PEV on concentration with respect to hydrodynamic volume may be used as an indication of shear degradation in the GPC.