Chromatographic fractionation of polyolefins

The results compare favorably with those obtained by careful refractionation of fractions isolated by the precipitation method. A convenient parameter, U , related to the breadth of the molecular weight distribution can be calculated from the slope of the log‐probability plot. When the plot is linear, U , is numerically equal to the ratio M w / M n . Values of U obtained for a number of commercial and experimental polypropylenes indicate that, with a given type of polypropylene, the breadth of the distribution increases as the average molecular weight of the sample increases, and that wide differences in distribution can be expected from polymers made by different processes.