PEER-REVIEWED ARTICLE bioresources.com Ching et al. (2015). “PVA/nanocellulose/nanosilica,” BioResources 10(2), 3364-3377. 3364 Preparation and Characterization of Polyvinyl Alcohol- Based Composite Reinforced with Nanocellulose and Nanosilica Yern Chee Ching, a, * Ashiqur Rahman, a Kuan Yong Ching, a,b Nazatul Liana Sukiman, a and Cheng Hock Chuah c This work reported the thermomechanical and morphological properties of polyvinyl alcohol (PVA) nanocomposites reinforced with nanosilica and oil palm empty fruit bunches derived nanocellulose. The nanocomposites were characterized by mechanical, thermal, XRD, optical, and morphological studies. Uniformity dispersion of the nanofillers at a 3 wt% concentration has been shown by scanning electron microscopy, whereas the changes in crystallinity were demonstrated by X-ray diffraction analysis. Addition of nanosilica resulted in increased thermal stability of PVA/nanocellulose composites due to the reduction in mobility of the matrix molecules. Visible light transmission showed that the addition of 0.5 wt% nanosilica only slightly reduced the light transmission of PVA/nanocellulose composites with 3 wt% nanocellulose. The addition of a small concentration of nanosilica successfully improved the tensile and modulus properties of PVA/nanocellulose composite films. The increases in tensile strength and thermal stability were evidence of a nanosilica contribution in PVA/nanocellulose composites, inducing reinforcement, as detected by the thermomechanical properties. Keywords: Oil palm empty fruit bunches (OPEFB); Nanocellulose; PVA; Nanosilica; Mechanical properties; Thermal stability; Optical properties Contact information: a: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia; b: Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, United Kingdom; c: Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia; *Corresponding author: chingyc@um.edu.my INTRODUCTION The use of natural fibers as reinforcing agents in composites has increased in recent years as global concerns over environmental issues rise. One of the common types of natural fibers is cellulose, an abundant natural resource. Cellulose contains nanosize fibrils that can be classified into a crystalline part (nanocellulose) and an amorphous part (Cho and Park 2011; Ching and Ng 2014). The cellulose chains are linked by hydrogen bonds between the hydroxyl groups that yield high stiffness and structural strength to the material. It has been reported that native cellulose crystal regions and tunicin whiskers have elastic modulii of 167.5 GPa (Tashiro and Kobayashi 1991) and 143 GPa (Eichhorn et al. 2010), respectively, compared to e-glass fiber with an elastic modulus of 73 GPa (Saheb and Jog 1999). The cellulosic materials are generally cheaper to produce, require less energy consumption, and are low-density, biodegradable, and biocompatible. The specific strength is also higher, hence it is less susceptible to fracture during processing (Kalaitzidou et al. 2007; Mandal and Chakrabarty 2011, 2014). Furthermore, the disposal of the composites can be done by combustion, which converts them into H2O and CO2