Influence of non-covalent functionalization of carbon nanotubes on the rheological behavior of natural rubber latex nanocomposites

Abstract

This paper aims at correlating the dispersion of multi walled carbon nanotubes (MWCNT) in natural rubber latex (NRL) medium with the rheological properties of nanocomposites. For this, MWCNTs were first treated with surfactants of different charges – anionic sodium dodecyl sulphate (SDS), cationic cetyl trimethyl ammonium bromide (CTAB) and non-ionic Tween 20 (TW) – prior to their latex dispersion by solution mixing. Simple techniques like UV visible spectroscopy and sedimentation index analysis are used to explore the better dispersion of surfactant/MWCNTs in aqueous medium, where the surfactants reduce the agglomeration and entanglement of the nanotubes and facilitate strong filler–polymer interfacial adhesion. Rheology of the NRL-MWCNT suspensions is applied to derive the CNT–latex interfacial interactions in a quantitative way. For this Maier-Göritz theoretical modeling is applied on the observed ‘Payne effect’. The effect of concentration of fillers, mixing time and temperature on the viscoelasticity of composites were also investigated. Contact angle measurements, transmission electron microscopy and Raman spectroscopy have been employed to substantiate the enhanced compatibility of surfactants wrapped MWCNTs with NRL where a promising dispersion and interfacial adhesion were achieved.