Elastomeric dielectric materials from natural rubber/copper-modified coconut-shell-derived activated carbon composite : combined experimental and density functional theory study

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Chailad, Wichain and Ariyawiriyanan, Warunee and Pavasupree, Sorapong and Sosa, Narongrit and Wongnongwa, Yutthana and Yuennan, Jureeporn and Martwong, Ekkachai and Ayutthaya, Siriorn Isarankura Na and Yang, Liu and Sukhawipat, Nathapong (2025) Elastomeric dielectric materials from natural rubber/copper-modified coconut-shell-derived activated carbon composite : combined experimental and density functional theory study. Industrial Crops and Products, 234. 121511. ISSN 0926-6690 (https://doi.org/10.1016/j.indcrop.2025.121511)

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Abstract

This study examines the enhanced dielectric and mechanical properties of natural rubber (NR) composites filled with copper-modified activated carbon (Cu-AC), employing both experimental characterization and density functional theory (DFT) simulations to explore structure-property relationships. NR composites were prepared with Cu-AC loadings of 5, 10, and 15 phr, and their performance was compared to those reinforced with neat activated carbon (AC). The effects of Cu-AC content on crosslink density, swelling behaviour, and curing characteristics were evaluated. SEM and EDX analyses confirmed good dispersion of Cu-AC particles, particularly at lower loadings. Mechanical testing revealed a significant increase in tensile strength and elongation at break, with the best balance of properties performed at 10 phr Cu-AC. Dielectric analysis showed increased interfacial polarization and charge storage, with the composite containing 15 phr Cu-AC exhibiting a dielectric constant of around 20 at 1 Hz, which is 2.68 times higher than that of neat NR. This enhancement was associated with interfacial polarization consistent with the Maxwell–Wagner–Sillars effect and the formation of conductive pathways by Cu-AC. However, due to reduced mechanical strength at higher loadings, the 10 phr Cu-AC composite was identified as the optimal formulation, offering a favourable combination of dielectric and mechanical performance. DFT calculations supported these findings, demonstrating strong NR–filler interactions, high adsorption energy (Eads) and significant charge transfer for copper-doped surfaces. These results highlight the multifunctional potential of Cu-AC as a reinforcing and functional additive in NR composites for use in flexible electronics, dielectric elastomers, and energy storage applications.

ORCID iDs

Chailad, Wichain, Ariyawiriyanan, Warunee, Pavasupree, Sorapong, Sosa, Narongrit, Wongnongwa, Yutthana, Yuennan, Jureeporn, Martwong, Ekkachai, Ayutthaya, Siriorn Isarankura Na, Yang, Liu ORCID logoORCID: https://orcid.org/0000-0001-8475-1757 and Sukhawipat, Nathapong;
CORE (COnnecting REpositories)