Tailoring Natural Rubber Properties through CaO Nanoparticle Integration and Curing Technique

The present study explores the development of natural rubber nanocomposites reinforced with calcium oxide nanoparticles and cured using pentane-1,5-diylidenediamine, a green crosslinker derived from glutaraldehyde and ammonia. calcium oxide nanoparticles (0.02–0.16 wt%) were incorporated via latex blending, and composites were evaluated in both uncured and pentane-1,5-diylidenediamine -cured forms. Fourier-transform infrared spectroscopy confirmed that the calcium oxide nanoparticles were well dispersed and actively involved in crosslinking with the rubber matrix. Scanning electron microscopy showed that the cured composites had a more uniform surface and better distribution of nanoparticles. Mechanical testing revealed a remarkable tenfold increase in tensile strength from 0.217 MPa to 8.478 MPa and a significant improvement in elongation at break, rising from 666–1317% in the pentane-1,5-diylidenediamine -cured samples. The best mechanical performance was achieved at 0.10 wt% calcium oxide. Dielectric measurements further highlighted an increase in permittivity and AC conductivity, especially in the cured composites, attributed to interfacial polarization and the formation of nanoparticle networks. Altogether, these results underline the synergistic benefits of calcium oxide nanoparticles and pentane-1,5-diylidenediamine curing in enhancing the structural, mechanical, and dielectric properties of natural rubber, making it a strong candidate for advanced elastomeric and dielectric applications.