Processing methods and vulcanization influence on the electrical and mechanical behavior of isoprene rubber/MWCNT composites

Abstract

The burgeoning electronics industry demands flexible and cost-effective electrodes. Despite their inherent insulating nature, conductive rubber composites offer compelling advantages due to their flexibility and resilience. Due to reinforcing properties and high electrical conductivity, these materials can be transformed into viable electrode candidates by incorporating conductive additives like carbon nanotubes (CNTs). This study investigates the influence of dispersion and vulcanization methods on the mechanical and electrical properties of polyisoprene/CNT composites, aiming to optimize their suitability for flexible electrode applications. Two dispersion methods (conventional two-roll mill and latex dispersion) and two vulcanization systems (efficient and conventional) were employed. Comprehensive characterization encompassed electrical (resistivity, impedance spectroscopy), mechanical (tensile tests, rheometry), and interfacial properties (contact angle, zeta potential, linear voltammetry). Results demonstrate that the latex dispersion method significantly outperforms the two-roll mill approach. Latex-dispersed composites exhibited a tenfold increase in electrical conductivity and superior surface properties compared to conventionally dispersed counterparts, from 0.123 to 1.33 mS cm⁻¹. Also, the efficient vulcanization system resulted in a modest decrease in modulus while maintaining tensile strength and significantly improving strain at break, from 1.83 to 6.82 MPa and 82.9 to 607%, respectively. This work provides valuable insights into optimizing dispersion and vulcanization techniques for developing high-performance conductive rubber composites with enhanced electrical and mechanical properties, which are crucial for advancing flexible electrode technologies.