Vulcanization kinetics of nitrile rubber/layered clay nanocomposites

Abstract

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/unmodified 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.

Nitrile rubber - based nanocomposites prepared by melt mixing: effect of the mixing parameters on mechanical, dynamic-mechanical and creep behavior

“…These results suggest an increase of the curing rate promoted by the quaternary alkylammonium salt present as the intercalant for the organoclay. Similar results have been observed by other authors [9,28] . The maximum torque also increased with the presence of clay.…”

“…The curing process has also been claimed by several authors as a very important factor governing the exfoliation/intercalation degree in rubber/clay nanocomposites. Nah et al [9,16] observed a shift of the X-ray diffraction peak related to the basal interspacing of the organoclay towards higher 2θ values after curing the melt blended nitrile rubber-clay system. The authors have suggested that part of the intercalated component in the clay were squeezed out from the layer, giving rise to some clay aggregates.…”

“…Indeed, the presence of clay resulted in a decrease of shear viscosity in some cases [5] . In this regard, several rubber/ clay nanocomposites using for example, carboxylated nitrile-butadiene rubber [6,7] , nitrile-butadiene rubber (NBR) [5,[8][9][10][11][12][13][14][15][16][17][18][19] , natural rubber (NR) [4,[20][21][22][23] , styrene-butadiene rubber (SBR) [5,19,24,25] , and ethylene-propylene-diene rubber (EPDM) [26,27] , among others, have been prepared via solution intercalation, melt intercalation and rubber latex compounding. Among these procedures, melt compounding is a very interesting process under the technological point of view because it does not require solvent to swell the clay, which constitutes an inherent advantage of industrial applicability and eco-friendliness.…”

Influência Dos Óleos Vegetais E Da Cera De Abelha Sobre a Vulcanização Do Copolímero De Estireno-Butadieno (Sbr)

“…Assim, o grau de conversão (  ) em uma reação de cura pode ser determinada a partir das propriedades viscoelásticas medidas através de um reômetro (CHOUGH e CHANG, 1996;LOPEZ-MANCHADO et al, 2003;CHOI et al, 2005). O valor de  pode ser definido pela Equaçao 1:…”

Micro-structural evolution of rubber/clay nanocomposites with vulcanization process

“…Most previous studies about the vulcanization kinetic of RCNs indicted that addition of OMC would considerably increase curing rate and crosslinking density of various rubber compounds, including NR [24,25], ENR [26], BR [27,28], SBR [29], EAR [30], NBR [31], and NBR/SBR blend [32]. On the other hand, some studies [12,33] on EPDM/OMC systems shown that addition of OMC prolonged the optimum curing time and reduced the cross-linking density of the composites.…”