Preparation and characterization of organoclay nanocomposites based on natural rubber

Rubber compounds based on natural rubber (NR) reinforced with octadecylamine-modified bentonite have been prepared via a vulcanization process and characterized by several techniques. The silicate nanolayers are exfoliated and uniformly dispersed in the polymer chains. Monsanto measurements have shown that the organoclay accelerates the vulcanization reaction and, furthermore, gives rise to a marked increase of the torque, indicating that the elastomer becomes more crosslinked in the presence of the organoclay. These results were corrobated by swelling measurements since a noticeable increase in the curing degree was observed when the organoclay was added to the rubber recipe. Moreover, thermodynamic parameters have shown an increase in the structural order of the nanocomposite. In addition, thermal analysis supports the assumption that the degree of curing of the elastomer increases when the organoclay is added to the elastomer. An appreciable increase of the involved heat during the curing reaction has been observed. Moreover, the T-g of the NR increases in the presence of the organoclay due to the confinement of the elastomer segment into the organoclay nanolayers, which restricts the mobility of the chains. (C) 2003 Society of Chemical Industry.