Role of Imidazolium Ionic Liquid in Tuning Electrical, Dielectric, and Viscoelastic Relaxation of Epoxidized Natural Rubber/ <scp>MWCNT</scp> Nanocomposites

ABSTRACT Epoxidized natural rubber (ENR)/multi‐walled carbon nanotube (MWCNT) nanocomposites incorporating the imidazolium‐based ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium chloride ([EMIM][Cl]) were prepared to investigate the effects of ionic liquids on curing behavior, electrical and dielectric properties, and stress‐relaxation behavior. The novelty of this work lies in correlating ionic‐liquid‐assisted CNT dispersion and ionic charge transport with temperature‐dependent viscoelastic relaxation in a polar, bio‐based rubber nanocomposite. Rheometric analysis showed that [EMIM][Cl] significantly accelerated sulfur vulcanization, reducing scorch time from 1.21 to 0.35 min and cure time from 4.43 to 3.29 min at 3 phr loading. Morphological observations revealed that low [EMIM][Cl] content suppressed MWCNT re‐agglomeration, whereas higher loadings (≥ 5 phr) induced micro‐phase separation of IL‐rich domains. Consequently, DC electrical conductivity increased from approximately 2.22 × 10 −5 S m −1 in IL‐free composites to ~1.19 × 10 −4 S m −1 at [EMIM][Cl] contents above 3 phr, accompanied by increased dielectric permittivity and dielectric loss. Temperature scanning stress relaxation (TSSR) showed that the pronounced low‐temperature relaxation peak (~50°C), associated with MWCNT agglomerate breakdown and bound‐rubber desorption, was suppressed by [EMIM][Cl]. However, excessive [EMIM][Cl] loadings accelerated stress relaxation and reduced thermal network stability due to plasticization and phase separation. Overall, [EMIM][Cl] primarily acts as a dispersion modifier and mobility enhancer in ENR/MWCNT nanocomposites.