Determination of branching of polyvinylchloride

The degree of branching of some samples of polyvinylchloride (PVC) was determined by hydrogenation of the polymer with LiAlH 4 followed by infrared measurements on the product so obtained. It is verified that during the hydrogenation process there does not occur any degradation of the polymer. The branching degrees are given as ratios of 100(CH 3 /CH‐ 2 ) which are determined from the ratios of the absorbances at 1378 and 1368 cm −1 by means of a calibration curve. The influence of some polymerization conditions on the degree of branching such as temperature, degree of conversion, and presence of the two diluents tetrahydrofurane and n ‐butyraldehyde were examined. Only the polymerization temperature is found to influence the degree of branching. The PVC samples prepared at 50°C have approximately one side chain for every sixty carbon atoms, whereas the samples prepared at temperatures below −60°C are practically linear.