Effect of Bi2O3 on the properties of linier low density polyethylene (LLDPE)/natural rubber (NR) composites

INTRODUCTION The use of thermoplastic natural rubber (TPNR) is spreading to many applications, such as in footwear, hoses, seals, automobiles, and marine engineering with the increasing interest in current environmental issues (Homkhiew et al., 2018). Thermoplastic natural rubber (TPNR) can be obtained from a blend of thermoplastics and natural rubbers. Among the thermoplastics, one of the most used in the world industry is linear lowdensity polyethylene (LLDPE). LLDPE is used in the industry of packaging (Cozzi et al., 2018), electrical insulating materials in power cables (Arief et al., 2016), and automotives (Ramkumar et al., 2014). In this paper, the making of TPNR for car floor mats was studied. Car floor mats are generally made from natural rubber and synthetic rubber, then vulcanized to provide products that are difficult to recycle. The development of LLDPE/ NR based TPNR materials was aimed to provide recyclable, high-density, and thermoformable car floor mats. Currently, high density TPNR is an imported product. The blend of LLDPE/NR has been widely studied by some researchers because LLDPE is suitable for blending with natural rubber attributable to its low melting temperature which can prevent the thermal degradation of rubber. However, the nature of TPNR, as a polymer, limits in several physical and mechanical properties, particularly hardness and stiffness. The addition of filler can improve the performance of TPNR. Arief et al. (2016) studied composites of linear lowdensity polyethylene/natural rubber (LLDPE/NR) with nano-silica and micro-scale Palm Oil Fuel Ash (POFA) fillers, and they found that the tensile strength of LLDPE/NR raised with the increasing of nano-silica content composition, but decreased with the increasing of POFA weight percentage. The use of high-density metal oxide fillers in thermoplastic material formulations are developed for a diverse specific end-use, for instance radiation shielding, projectiles, electronic components, and packaging, offers benefits, such as sustainable, ABSTRACT The use of thermoplastic natural rubber (TPNR) has spread for many applications such as in footwear, hoses, seals, and automobiles. This increase is in line with the environmental awareness to produce materials that can be recycled. In this paper, the making of TPNR for car floor mat was studied. Bi2O3 filler was added to modify the performance of TPNR for car floor mat. In this study, the effects of Bi2O3 filler on the properties of linear lowdensity polyethylene (LLDPE)/natural rubber (NR) composites had been investigated. The weight ratio of LLDPE/ NR was varied at 90/10; 80/20; 75/25; and 70/30. Bi2O3 filler loading was varied at 0; 20; 40; and 50 phr. The increase in NR and Bi2O3 filler reduced the tensile strength, elongation at break, and tear resistance, but increased the hardness and density of the composites. Compared to similar imported products, the samples prepared in this study showed higher values for all mechanical properties (tensile strength, elongation at break, tear resistance) but lower values in density. Scanning electron microscopy (SEM) micrograph of LLDPE/NR 75/25 composites either with or without the addition of 20 phr Bi2O3 filler displayed homogeneity of the mixture.