Scalable processing of thermoplastic polyurethane nanocomposites toughened with nanocellulose

• Thermoplastic polyurethane (TPU) is toughened with high aspect ratio nanocellulose.
• Scalable approach of processing nanocomposites is shown via reactive extrusion.
• The ‘polyol-nanocellulose dispersion route’ could reduce the usage of organic solvent.
• With 0.5 wt.% spinifex nanocellulose, TPU showed up to 43% improvement in tensile strength.
• It can be an attractive approach for polymerisable/curable systems.

The production of strong and elastic polyurethane nanocomposites toughened with nanocellulose (NC) and their widespread application in many engineering fields are currently limited by poor processability via classical industrial processing methods and/or the usage of large amount of solvents. In this report, we demonstrate a scalable, organic solvent-free incorporation of nanocellulose into thermoplastic polyurethane (TPU) and a remarkable reinforcement without compromising elastic properties. The nanocomposites were prepared via water-assisted dispersion of nanocellulose in polyether polyol by bead milling, drying and reactive extrusion of this dispersion with comonomers. Upon the incorporation of nanocellulose (0.5 wt.%), as observed from infrared spectroscopic and thermal analysis, the phase mixing of hard and soft-segments in the TPU matrix and the primary relaxation temperature have slightly increased due to the hydrogen bonding, interfacial area and nucleation-enhanced by long polar nanocrystals. The TPU/nanocellulose nanocomposites prepared with an appropriate stoichiometric ratio (determined through appropriate process control) showed a remarkable improvement (up to 43%) in ultimate tensile strength without compromising the elastic properties including elongation, creep and hysteresis.

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