Use of expanded perlite as green filler for the preparation of EPDM-perlite rubber composites with improved thermal stability and insulation properties

The present study investigated the use of expanded perlite (e-perlite) as a sustainable and cost-effective filler for EPDM (ethylene propylene diene monomer) rubber composites. Various amounts of e-perlite were incorporated into EPDM to assess its impact on the composite properties, such as curing characteristics, physical and mechanical properties, crosslink density, thermal conductivity, thermal stability, surface roughness, and contact angle. The composite with 15 phr of e-perlite exhibited approximately 20% higher crosslink density and a 12% increase in hardness, while slight decreases were observed in elongation at break and tensile strength. The FE-SEM (field emission-scanning electron microscopy), atomic force microscopy, and contact angle analysis have been performed to investigate the surface morphology and the hydrophobicity. The thermal properties of the composites were assessed through thermogravimetric analysis, thermal aging tests, and thermal conductivity measurements. The results showed that e-perlite significantly improved the aging resistance and the thermal stability. The composites with 15 phr e-perlite exhibited a 21% reduction in thermal conductivity and enhanced thermal isolation properties compared to the EPDM composite without e-perlite. This work demonstrated the potential utilization of e-perlite in EPDM as a green sustainable filler to enhance the thermal insulation and the stability properties of the composites, which may have practical applications in automotive, aerospace, construction, and electronic industries.