The use of montmorillonite as a reinforcing and compatibilizing filler for NBR/SBR rubber blend

Montmorillonite clay was added at different ratios to some polymer blends of acrylonitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR). Both the reinforcing and compatibilizing performance of the filler were investigated using rheometric measurements, physico-mechanical properties, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). There was a remarkable decrease in the optimum cure time (tc(90)) and the scorch time (ts(2)), which was associated with an increase in the cure rate index (CRI), with filler loading up to 20 phr in the different blend ratios. The stress at yield was 2.5-5 times higher in the case of the filled blends, also the strain at both yield and rupture increased with the use of the filler for the different blend compositions, while the resistance to swelling in toluene became higher. SEM photographs show that the filler is located at the interface between the different polymers which induces compatibilization in the immiscible blends. DSC scans of the filled blends showed shifts in the glass transition temperatures T-g which can be attributed to the increased strength at the interface. (C) 2004 Elsevier Ltd. All rights reserved.