Carboxylated Acrylonitrile Butadiene Rubber Research Articles

Structure of carboxylated acrylonitrile‐butadiene rubber (CNBR)–clay nanocomposites by co‐coagulating rubber latex and clay aqueous suspension

AbstractCarboxylated acrylonitrile‐butadiene rubber (CNBR)–clay mixtures were prepared by co‐coagulating rubber latex and clay aqueous suspension, then combining the mixtures with a rubber ingredient and vulcanizing by a traditional rubber mixing processing procedure. Transmission electron microscopy (TEM) showed that the silicate layers of clay were delaminated or intercalated with CNBR and dispersed in the CNBR matrix at a nanometer level during co‐coagulating. X‐ray diffraction indicated that the amount of CNBR intercalating between the layers increased with the increase of content of clay in CNBR, which is in contrast with the results of other studies. Some reasons were put forward for this discrepency. The aspect ratio (width/thickness) of the platelet inclusions was reduced and the silicate layers were aligned more orderly during the compounding operation on an open mill. The intercalated CNBR, on co‐coagulating, still remained within the interlayer space after curing. In these nanocomposites, the particles of silicate layers were dispersed at the nanometer level and the structure was a combination of delaminated and intercalated silicate layers dispersed in the continuous CNBR matrix. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2842–2848, 2001

Studies on rubber–filler interaction in carboxylated nitrile rubber through microhardness measurement

The influence of carbon black filler loading on the microhardness characteristics of two types of carboxylated acrylonitrile butadiene rubber (XNBR) vulcanizates having different (ionic or covalent) crosslinking reaction systems has been studied. The microhardness measurement predicts that the rubber–filler interaction in the ionic crosslinking system is higher than that in the covalent crosslinking system. The high hardness values and strong rubber–filler interaction in the ionic crosslinking system has been explained on the basis of ionic cluster formation for the carboxylate salt in XNBR. The microhardness measurement result helps to evaluate the rubber–filler interaction and shows good correlation with the dynamic mechanical result. The theoretical predicted data deviate highly in the ionic crosslinking system, although there is a good correlation in the covalent crosslinking system.