Characterization of natural rubber nanocomposites filled with organoclay as a substitute for silica obtained by the conventional two-roll mill method

The aim of this study was to evaluate the technical feasibility of natural rubber nanocomposites with Cloisite 15A (R), a commercial organoclay (OC) to substitute for conventionally used silica (SiO2) as a filler. Three clay polymer nanocomposites (CPN) were prepared while varying the content of OC (2, 4 and 8 phr - parts per hundred of rubber). For comparative purposes, a sample with 50 phr of silica was also prepared and analyzed. The compounds were characterized by their rheological, morphological, thermal and mechanical properties. The mechanical properties were also determined after the accelerated aging of the compounds. The results revealed the intercalation of the OC by the rubber chains in the CPN, which reduced the enthalpy of the curing process and indicated a lower crosslink density. The TEM analysis indicated that the OC was homogeneously dispersed in the CPN. The set of results for the mechanical properties indicated that 50 phr silica can be replaced by 4 phr OC without affecting the properties of the final material even after aging. (C) 2011 Elsevier B.V. All rights reserved.