Effect of nanofibril cellulose empty fruit bunch‐reinforced thermoplastic polyurethane nanocomposites on tensile and dynamic mechanical properties for flexible substrates

Abstract Researchers and scientists have focused on the development and future opportunities of flexible sensors in food, environment and defense fields. In this study, we propose a flexible substrate material‐based nanofibril cellulose empty fruit bunch (NEFB)‐reinforced thermoplastic polyurethane (TPU) blend nanocomposite for flexible substrate materials. Untreated and treated nanofibril cellulose samples of empty fruit bunch (NEFB, 0, 1, 2, 3, 4 wt. %) were treated with 6 wt.% sodium hydroxide (NaOH) and subjected to internal Brabender mixer followed by a hot‐pressing machine. The density and tensile and dynamic mechanical properties of the nanocomposites were investigated for the treated and untreated samples. Tensile properties were characterized using a Universal Testing Machine, and the fracture mechanism after post‐tensile testing was determined by scanning electron microscopy (SEM). Increasing the content of untreated NEFB/TPU improved the tensile strength compared with 6% treated NEFB/TPU blend nanocomposites. Incorporating the nanofibril cellulose of empty fruit bunch at 2% into the TPU blend nanocomposites significantly increased E ′, E" and T _g compared with other formulations. Highlights Nanocellulose derived from plants is considered a promising material for flexible substrates in electronics due to its robust mechanical properties and eco‐friendliness. Malaysia's abundant empty fruit bunch (EFB) resources make it a possible source of nanocellulose, which improves the properties of polymers. The effect of sodium hydroxide (NaOH) treatment on the compatibility of EFB‐derived nanocellulose with polymer matrices was investigated. The addition of nanocellulose, particularly at a concentration of 1%, significantly increases the tensile strength of thermoplastic polyurethane nanocomposites, whereas 6% NaOH treatment has no effect. Dynamic mechanical analysis reveals high storage modulus at 2% nanofibril cellulose empty fruit bunch (NEFB) and energy dissipation at 4% NEFB as well as enhanced interfacial bonding at 1% NEFB.