Dynamic mechanical properties and swelling behaviour of NR/reclaimed rubber blends

The dynamic mechanical properties and swelling behaviour of two natural rubber (NR) (STRVS60 and STR20CV) vulcanizates filled with different reclaimed rubber contents were examined with respect to loss tangent (tandelta) and the change in glass transition temperature. Tandelta(max) was found to shift to higher temperature, and the peak height reduced with increasing reclaimed rubber content. An increase in the overall width of the tandelta peaks was associated with the presence of styrene-butadiene rubber (SBR) in the reclaimed rubber. T-g was found to increase with reclaim content due to an increased cross-link density, and presence of carbon black in the reclaim. The change in cross-link density was more dependent on the vulcanizing recipe than the initial molar mass of the rubber. The equilibrium swelling of the NR vulcanizates was observed to reduce with increasing reclaimed rubber content due to the increases in cross-link density and the polymer-solvent interaction. (C) 2003 Elsevier Science B.V. All rights reserved.