Study of entangled network formation in concentrated solutions of polymer by ~(13)C NMR

摘要

Information about the exact location of topological and cohesional entanglements at molecular level has been obtained by ~(13)C NMR relaxation analysis. The results show that about 20% of the carbon atoms in the main chain are entangled in the 25% (by weight) solution, which is independent of the content of the 1,2-segment in polybutadiene and of the kind of solvent. However, the entanglement of the carbon atoms on the end group of the side chain is very weak, they behave as slipping freely at the junctions.