PEER-REVIEWED ARTICLE bioresources.com Lotfi et al. (2015). “Surface mod. seed shell composites,” BioResources 10(2), 3409-3425. 3409 Surface Modification of Elateriospermum tapos Seed Shell Recycled Polypropylene Composites Muhamad Nadhli Amin Lotfi, Salmah Husseinsyah*, Hakimah Osman, and Hanafi Ismail The influence of the filler content and surface modification of Elateriospermum tapos seed shell (ETSS)-filled recycled polypropylene (rPP) on the tensile, thermal, and morphological properties was investigated. Maleic acid (MA) was used for the chemical modification of ETSS. It was found that increasing the ETSS content decreased the tensile strength and elongation at break of composites. However, the modulus of elasticity increased with the addition of ETSS. The thermal properties of composites were examined using thermal analysis (TGA) and differential scanning calorimetry (DSC). The addition of ETSS indicated better thermal stability of rPP/ETSS composites. The degree of crystallinity (Xc) of the composites decreased with increasing ETSS content. The tensile strength and modulus of elasticity of modified composites was higher than unmodified composites. Surface modification with maleic acid increased the thermal stability and crystallinity of the modified rPP/ETSS composites. Scanning electron microscopy showed that the filler-matrix interaction improved with the modification of ETSS with maleic acid. Keywords: Recycled polypropylene; Elateriospermum tapos seed shell; Maleic acid; Surface modification; Composites Contact information: Division of Polymer Engineering, School of Materials Engineering, Universiti Malaysia Perlis, 02600, Jejawi, Perlis, Malaysia; *Corresponding author: irsalmah@unimap.edu.my INTRODUCTION Currently, the rapid development of polymer usage has led to the dramatic rise of what is commonly referred to as the “green movement.” As part of the green movement, people are conscious about environmental pollution due to overconsumption and the disposal of plastic waste in landfills. The green movement shows how environmental awareness has increased among individuals, which has forced the industry to be much more concerned about waste disposal management and the development of plastic-based materials. The conventional method was largely concentrated on landfill disposal. Thus, the industry has moved to the much more acceptable option of recycling (Aurrekoetxea et al. 2001). This movement has also become a very large influence for scientists to research how to recycle plastic and make biodegradable products, such as biodegradable composites (Liu et al. 2005; Saxena et al. 2008; Kalia et al. 2009). Traditionally, polymer composites were prepared using synthetic fillers such as glass, carbon, and other synthetic fibers. However, these are considered harmful because they are not biodegradable and can cause harm to the environment. Lately, studies using