Transport of aromatic solvents through nitrile rubber/epoxidized natural rubber blend membranes

Improving the Mechanical Properties of ENR/NBR Blends via Masterbatches with Initial Accelerator Concentration Gradients

Epoxidized natural rubber with 30 mol.% of epoxide (ENR-30) was blended with medium nitrile rubber (NBR) at the blend weight ratios of 30/70 and 70/30. Blend compounds were prepared via simple mixing and masterbatch techniques using TBBS as an accelerator. The masterbatches of ENR-30 initially consisted of higher accelerator concentrations compared with those of NBR, in order to compensate an effect of accelerator partition towards NBR phase. The initial accelerator concentration ratios in ENR-30 and NBR masterbatches before blending were at 50/50, 60/40, 70/30 and 80/20, respectively. The blend vulcanizates prepared by masterbatch mixing showed a significant improvement in tensile properties in comparison with those prepared by simple blend, and the initial accelerator concentration ratio in ENR-30/NBR masterbatches at 70/30 gave the highest ultimate tensile properties. The improvement in tensile properties was clearly observed for all the blends vulcanized with conventional, semi-EV and EV sulfur-vulcanization systems. The increase of tensile properties does suggest a better curative distribution, and hence a better crosslink distribution.