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The effects of weight-average molecular weight (M W) and short and long chain branching on the linear viscoelastic behavior of polyethylene (and ethylene−α-olefin copolymers) are described. Short chain branching had no effect up to a comonomer (butene) content of 21.2 wt %. The zero shear viscosity of the linear polyethylenes scaled in the expected manner with M W. Using a high molecular weight, narrow molecular weight distribution (MWD), linear polyethylene, an estimate of the plateau modulus and molecular weight between entanglements (M e) was obtained. A solution property based technique for quantifying levels of long chain branching well below 1 LCB/104 C in polyethylene is presented. Also, the applicability of 13C NMR for measuring such LCB levels is demonstrated. For metallocene polyethylene, long chain branching (LCB) increased the zero shear viscosity as compared to that of a linear material of the same molecular weight. LCB also broadened the relaxation spectrum by adding a long time relaxation mode that was not present for the linear polyethylene with the same MWD.

No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner. JMD wishes to acknowledge the support and encouragement of McGill University for providing a working environment conducive to a major writing project. He also wishes to recognize the colleagues and research students who have played a vital role in the development of his understanding of polymer rheology and its applications. In addition, JMD wishes to express his appreciation to the University of Wisconsin, especially to R. B. Bird and A. S. Lodge, for their professional hospitality during the time when he got his part of the writing well launched.KFW wishes to acknowledge the management of Hoechst Celanese for their permission to participate in this book. He also PREFACE vii wishes to thank his many colleagues at Hoechst Celanese, in particular H. M. Yoon, and his colleagues at the University of Delaware, most especially A. B. Metzner, for their contributions to his experience and knowledge of the fields discussed in this book. Others to whom appreciation is due include W.

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