Polyurethane cross-linking by chromium(III) compounds

Dynamic mechanical measurements were carried out to characterize the influence of chromium dioxide and chromium(III) chloride magnetic pigments on the structure of linear segmented polyurethanes. Both the chromium dioxide and the chromium(III) chloride act as curing agent. The network formation depends on the structure of the polyurethanes and the concentration of the chromium compounds. Nuclear magnetic resonance (NMR) measurements confirmed that chromium(III) chloride shows a strong interaction with the urethane group (NH and CO) by complex formation and a moderate interaction with the ester group (CO). The results are used to discuss a model structure for the modified polyurethanes.<
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