Correlation of Vulcanization and Viscoelastic Properties of Nanocomposites Based on Natural Rubber and Different Nanofillers, with Molecular and Supramolecular Structure

Abstract

Abstract Elastomer nanocomposites reinforced with low volume fraction of nanofillers, such as nanoclays and carbon nanofibers, have long been known to possess significantly improved mechanical, thermal, dynamic mechanical, flame retardant, and barrier properties. The present work attempts to evaluate the effect of nanofillers (like modified and unmodified montmorillonite, sepiolite, carbon nanofiber, and carbon black) and their amount on vulcanization, as well as dynamic and rheological properties in the prevulcanization and postvulcanization stages. Upon using organomodified nanoclay, optimum cure time was reduced and cure rate index increased; whereas, in comparison, carbon nanofiber resulted in a slower cure. The influence of loading of some representative nanofillers on natural rubber was studied through qualitative description of critical dynamic viscoelastic parameters, which indicated the formation of supramolecular structure even at low volume fraction. The nanocomposite vulcanizates showed solidlike rheological behavior and upon implementation of dispersion techniques the activation energy of flow was reduced by around 60%. The knowledge of cure and rheological properties of the compounds, which evolves from the structure formation, can be utilized for assessing process optimization, cost reduction, and performance of the nanocomposites.