Estimation of carboxy‐terminated polybutadiene functionality distribution via fractionation on silica gel

Abstract

AbstractSeparations of carboxyl‐terminated polybutadiene (CTPB) liquid polymer according to functionality have been effected by using stepwise elution from silica gel. Recoveries in the 90–95% range have been achieved by deactivating the silica gel and recycling the unfractionated portion through progressively more active silica gel. Subjection of the fractions obtained from the silica‐gel separation to analysis via gel‐permeation chromatography and infrared spectroscopy yields not only functionality distribution data, but also provides an estimation of the relationship between molecular weight distribution and functional type. Repetitive analyses indicate a precision of ±7% (or less) of the amount of each functionality type present. An evaluation has been made of the accuracy of the data by fractionating saturated and methyl ester derivatives of CTPB under test conditions different from those employed in fractionating the original polymer. Within the known experimental error of the techniques employed, these studies have confirmed the data generated for CTPB polymer as received. Analytical techniques and interpretation of data are discussed.