Klaus Unseld

In situ investigation of SBR vulcanization: A combined study of1H-NMR and vulcametry

For the first time, in situ NMR measurements were performed during sulfur vulcanization of unfilled SBR. A vulcanization device was constructed for use in combination with a standard microimaging probe in a vertical bore NMR magnet.1H-linewidth measurements are correlated with cure simulations in a vulcameter to explain the increase of the linewidth during the vulcanization. Inhomogeneous heating conditions in the sample result in an inhomogeneous course of the vulcanization as a function of time. The spatial dependence of this process was monitored by NMR imaging.

The interface between covulcanized rubber sheets by NMR imaging, scanning FTIR spectroscopy, and mechanical indentation mapping

Depending on compounds and vulcanization conditions an interface can be detected between covulcanized rubbers sheets which exhibits properties different from either of the pure compounds. This interface has been analyzed in NR/SBR covulcanizates by different techniques of NMR imaging including spectroscopic imaging to differentiate different chemical compounds. These investigations were complemented by scanning Fourier infrared spectroscopy and mechanical indentation mapping. The current understanding is that the interface is harder than the SBR and NR regions and typically of the order of 200 μm thick.