Effects of Layered Silicate Fillers and Their Surface Treatments in NR/BIIR Blend

In this study, the improvement in mechanical properties and abrasion resistance of natural rubber/bromobutyl rubber (NR/BIIR) blends were investigated when using different types of layered silicates as secondary fillers. Moreover, the effects of organophillic surface treatments and their synergistic effects with ENR compatibilizer were also studied. These fillers include montmorillonite clay, kaolin, bleaching clay, and talcum. We found that the secondary fillers could improve the properties of the rubber composites differently. Bleaching clay contributed to a dramatic increase in crosslink density, which could also increase the modulus and hardness of the composite. Montmorillonite clay could provide dramatic increase in abrasion resistance with low compression set, while kaolin was excellent in terms of tensile strength. With organophillic surface treatments, the silane-treated kaolin led to dramatic improvement in all aspects. Conversely, montmorillonite clay treated with octadecylamine contributed to significantly higher modulus and hardness, while losing its abrasion resistance and resilience. These results were opposite for bleaching clay. In this case, even though the composites of silane-treated kaolin obtained improved abrasion resistance and lower compression set, they suffered the drop in crosslink density, modulus, hardness and tensile strength.