Development of a competitive thermoplastic vulcanizate roofing sheet from natural rubber and high-density polyethylene

Abstract

Clay, asbestos, plastic and metal are commonly used as roofing materials in Sri Lanka and every material has its inherent drawbacks. Asbestos sheets are going to be banned due to health hazards. Thermoplastic Vulcanizate (TPV), a kind of polymer blends, gives combined properties of their individual polymers. Therefore, this study was aimed to develop a health hazard-free and economically viable roofing material from TPV to be competitive with the existing roofing materials. TPV pellets of 20/80 Natural rubber (NR)/High-Density Polyethylene (HDPE) in two different formulas were prepared using a twin-screw extruder. Roofing sheets having size of 40 cm × 40 cm × 0.6 cm were moulded using TPV pellets. Properties were tested according to the ASTM standards for Poly-Vinyl Chloride (PVC) roofing sheet and the certificates for properties of the PVC roofing sheets available in Sri Lanka. Properties of the two TPV sheets prepared were compared with those of the PVC sheets. TPV sheet having 1 phr of dicumyl peroxide and 50 phr of barium sulphate showed the optimum properties and were comparable with impact strength, elongation at break, density and thermal conductivity of PVC roofing. The developed TPV sheet is cost competitive and suitable for the high-class customer segment.