Physical Properties and Cure Characteristics of Natural Rubber/Nanoclay Composites with Two Different Compatibilizers

The effects of epoxidized natural rubber (ENR) and maleic anhydride-grafted polybutadiene (PB-g-MA) as compatibilizers to rubber formulations with and without organo-modified layered silicates are investigated. The physical properties and curing characteristics of composites are studied by moving die rheometer, rubber process analyzer, tensile, tear, and hardness testing. The state of organoclay intercalation was determined by X-ray diffraction method. The addition of compatibilizers, especially ENR 50, results in further intercalation or exfoliation of the organoclay that increased the clay dispersion in the rubber matrix. ENR 50 with organo-modified clay improves the physical properties and changes the curing profile. The addition of PB-g-MA without organoclay increases the tensile strength (sigma(max)) by increasing the stock viscosity of the rubber compound. Interestingly, simultaneous increase in hardness and sigma(max) is achieved in the presence of both compatibilizers, a characteristic that is difficult to achieve and sometimes required in rubber processing. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1530-1535, 2011