Using solvents to improve the chemical shift differences between short-chain branch methines and long-chain branch methines in polyethylene copolymers

Abstract

Detection and quantification of long-chain branches in some polyethylene copolymers is challenging due to the near coincidence of the chemical shifts for the carbons at the short-chain and long-chain branches present in these copolymers. The small chemical shift difference can be enhanced by changes in solvent and temperature. This allows one to use lower field magnets for some copolymers. Results are presented comparing several solvents and blends at a variety of temperatures using 500, 600 and 750 MHz spectrometers. Copyright ©2007 WILEY-VCH Verlag GmbH & Co. KGaA,.