PEER-REVIEWED ARTICLE bioresources.com Surya et al. (2019). “Natural fillers in latex foam,” BioResources 14(4), 9375-9391. 9375 Effect of Partial Replacement of Kenaf by Empty Fruit Bunch (EFB) on the Properties of Natural Rubber Latex Foam (NRLF) Indra Surya, a Siti Nurul Izzati Kudori, b and Hanafi Ismail b, * Kenaf was replaced by various amounts of empty fruit bunch (EFB) in natural rubber latex foam (NRLF). Five different compositions of kenaf/EFB (7/0, 5/2, 3.5/3.5, 2/5, 0/7 phr) were prepared by using the Dunlop method. The comparison of tensile properties, morphology, foam density, compressive strength, hardness, swelling, compression set, and accelerated aging of natural rubber latex foam (NRLF) were studied. The tensile strength, modulus at 100% ( M100), foam density, compressive strength, hardness, and compression set decreased with increasing EFB loading. However, the elongation at break and swelling percentage of NRLF increased as the content of EFB decreased. Morphological studies showed that a higher amount of EFB weakened the interaction between EFB and NRLF matrix and increased the formation of cell windows. The EFB-filled NRLF also showed better tensile retention compared to kenaf filled NRLF. Keywords: Natural rubber latex foam; Kenaf; Empty fruit bunch; Tensile properties Contact information; a: Department of Chemical Engineering, Faculty of Engineering, Universitas Sumatera Utara, Medan, 20155 Indonesia; b: School of Materials and Mineral Resources, Engineering Campus, Universiti Sains Malaysia, Malaysia; *Corresponding author:profhanafi@gmail.com INTRODUCTION The use of lignocellulosic materials such as wood or cellulose in the production of natural rubber-based product is becoming more common (Ismail et al. 2012; Ramasamy et al. 2012; Norjulia et al. 2016). Lignocellulosic materials have many advantages compared to synthetic materials such as being less abrasive to the equipment, low density, renewable character, and environmental friendliness (Xu et al. 2012). Natural fibers promote the ‘green’ economy based on energy efficiency. The organic waste that results from the processing can be used as a fuel and generate the electricity. The selection of natural fibers usually depends on its geographical availability (Pickering et al. 2016). For example, Europe is known for flax fiber (Foulk et al. 2002), while the fibers attracting the biggest interest in Asian regions are jute, kenaf, and rice husk (Tripathy et al. 2000; Aji et al. 2009; Akil et al. 2011). Kenaf (Hibiscus cannabinus) originated from West Africa. It is a warm seasonal plant and can grow under a wide range of weather conditions, either in heavy rainfall or high solar radiation (Ashori et al. 2006; Akil et al. 2011). Kenaf can be harvested after 3 months of plantation and absorbs more carbon dioxide (CO2) than other crops (Saba et al. 2014). The stem and bark of the kenaf have distinct qualities and can be used in various products, for example, car accessories, animal feed, biofuels, and paper-based products (Ismai et al. 2011). Kenaf has been established in Malaysia as a new industrial crop with high potential for product development (Subramaniyan et al. 2013).