Comparison of different methods for the investigation of the short-chain branching distribution of LLDPE

The aim of this paper is the comparison of three different methods for the investigation of the short-chain branching distribution of linear low-densi ty polyethylene and the analysis of the composition of polyolefin blends. T he three methods to be compared are analytical temperature rising elution f ractionation (TREF), the commercialized Crystaf(R) technique, and a method based on differential scanning calorimetry with a special sample preparatio n procedure. This paper also discusses the specific advantages and disadvantages of each method by comparing the results for selected Ziegler-Natta and metallocene LLDPE (ZN-LLDPE and mLLDPE, respectively) and a model blend of LLDPE, HDPE and PP. As is demonstrated for these materials the three analytical method s yield comparable results with respect to the comonomer distribution of LL DPE. For the investigation of polyolefin blends the combination of the thre e methods is found to be recommendable, especially if polymers with high de grees of supercooling like polypropylene are involved. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.