CRYSTALLIZATION ANALYSIS FRACTIONATION - A NEW TECHNIQUE FOR THE ANALYSIS OF BRANCHING DISTRIBUTION IN POLYOLEFINS

A new technique to analyze the short-chain branching distribution (SCBD) in linear low-density polyethylene has been developed. The technique referred as crystallization analysis fractionation is based on a stepwise precipitation approach. By monitoring the polymer solution concentration during crystallization, the cumulative and differential SCBD can be obtained without the need of physical separation of fractions. The new technique has been shown to provide similar results to temperature rising elution fractionation but in a shorter time and with a simplified apparatus. It allows the simultaneous analysis of various samples and could also be used for analysis of polypropylene and other semicrystalline polymers that can be fractionated on the basis of crystallizability. (C) 1994 John Wiley & Sons, Inc.