Vulcanization kinetics of nitrile rubber/layered clay nanocomposites

Cure kinetic studies on nitrile rubber(NBR)layered clay nanocomposites, prepared by a melt mixing process, was investigated using a cure rheometer and differential scanning calorimeter (DSC). The characterization of the structure of the nanocomposites of uncured and cured samples was performed using X-ray diffraction. The results showed that the interlayer spacing of cured nanocomposites was smaller than that of the uncured sample due to partial removal of organoclay from the interlayer spacing. The cure characterization showed a marked decrease in the scorch time of the NBR/organoclay system without affecting the optimum cure time and torque values due to the accelerating and plasticizing effect of organoclay. DSC analysis showed a reduction in cure time and increase in enthalpy of curing for the compounds added with organoclay. There was a little change in cure behavior of the NBR/unmodifted clay system. NBR/clay nanocomposite showed the suitability of autocatalytic model for analyzing the cure parameters of rubber/clay nanocomposites. The activation energy of curing of NBR/O-MMT nanocomposites was lower than that of pristine NBR. The kinetic parameters determined from the model equation showed close fitting with the experimental results, indicating the suitability of autocatalytic model for cure characterization. (c) 2005 Wiley Periodicals, Inc.