Effect of particulate fillers on natural rubber/high-density polyethylene blends for roofing application

Blending of two or more polymers generates a new material, which is more cost-effective than a newly synthesised material. Blending-type thermoplastic elastomer (TPE) is produced by melt-mixing of a thermoplastic with a rubber. These blends have high demands associated with excellent property combinations of the parent materials. Particulate fillers are used in the rubber and plastic industry for property modification and cost reduction. In this work, six particulate fillers, namely, calcium carbonate, barium sulphate (BaSO ₄ ), kaolin, talc, Snobrite clay and dolomite were used to develop natural rubber (NR)/high-density polyethylene (HDPE) TPE blends, and the most suitable filler for roofing application was identified. A series of NR/HDPE 20/80 blends were prepared by varying filler loading from 10 phr to 30 phr at 10 phr intervals using a Plasticorder. Mechanical properties, such as tensile strength, hardness, impact strength and tear strength, and gel content of the blends were investigated. The addition of talc, dolomite and kaolin to NR/HDPE blend showed reduced impact strength, which is the most important property for a roofing application. The other three fillers showed improved impact strength at specific loadings. The blend with 30 phr of BaSO ₄ was identified as the best blend, as per the overall performance.