Determination of low amounts of long-chain branches in polypropylene using a combination of chromatographic and rheological methods

The focus of our investigations lies on the detection of low amounts of long-chain branching (LCB) in isotactic polypropylene (iPP) created by electron beam irradiation. The modified samples were investigated by rheological experiments in shear and elongational flow and by size-exclusion chromatography. The comparison of the results demonstrates the efficiency and the detection limits of these methods, particularly at very low degrees of long-chain branching. The combination of chromatographic and rheological methods enables a sensitive and comprehensive way for the characterisation of the long-chain branching phenomena. (C) 2004 Elsevier B.V. All rights reserved.