Recently Dr Andy Chapman, Head of Advanced Materials & Product Development Unit at the laboratories, co-authored a review with the Director of Research Dr Andrew Tinker, that was published in Kautschuk Gummi Kunststoffe. The subject of the review was vulcanization of blends, with emphasis on the work at the laboratories using swollen-state NMR characterisation and a network visualization technique. A method of visualizing networks of unsaturated elastomers was developed by TARRC scientists to estimate crosslink densities for a range of elastomer vulcanizates including NR, SBR, CR, NBR and EPDM. The method involves swelling the vulcanizate to equilibrium with styrene, polymerising the styrene, then sectioning the embedded, swollen vulcanizate and staining with osmium tetroxide to reveal a rubber mesh structure when observed by transmission electron microscopy (TEM). Measurement of this structure reveals a linear correlation between the mean mesh diameter and the molecular weight between crosslinks. This technique of network visualization is also useful in the study of polymer blends and latex films where measurement of localized crosslink densities and assessment of interfacial behaviour cannot be readily achieved by other means.

For further information please contact Dr Andy Chapman