Conductive natural rubber/carbon black nanocomposites via cellulose nanowhisker templated assembly: tailored hierarchical structure leading to synergistic property enhancements

Abstract

The development of novel and versatile strategies to construct conductive polymer composites with low percolation thresholds and high mechanical properties is of great importance. In this work, a simple, facile and effective strategy was developed to fabricate tailored carbon black (CB) based 3D hierarchical conductive structures in a natural rubber (NR) matrix using renewable and biodegradable cellulose nanowhiskers (CNs) as templates. Specifically, needle-like CNs can direct the arrangement of CB nanoparticles along the CNs, yielding nodular CB@CN nanohybrids with excellent suspension stability and high aspect ratios. As a result, CB@CN nanohybrids could be selectively located in the interstitial space between NR latex microspheres and assembled into a continuous 3D hierarchical network via a latex blending technique. This 3D hierarchical conductive structure dramatically enhanced the electrical and mechanical properties of the NR based composites. With the addition of 5 vol% CB, the electrical conductivity of the composite was significantly enhanced by 12 orders of magnitude and the tensile strength was increased by 760% after the incorporation of the CN templates. Moreover, CB@CNs/NR nanocomposites showed a much lower electrical conductivity percolation threshold (2.9 vol%) than the traditionally prepared CB/NR composites (7.3 vol%). This novel strategy of CN templated fabrication of effective 3D conductive structures in a polymer matrix could significantly promote the functional use of natural cellulose resources and extend the application of CB in the production of conductive composites.