A cleaner processing approach for cellulose reinforced thermoplastic polyurethane nanocomposites

Abstract

In a manner of addressing challenges in scalable processing of thermoplastic polyurethane (TPU) nanocomposites through extrusion methods, this study reports a very clean processing approach of incorporating cellulose nanocrystal (CNC) into a TPU matrix, with no acid or organic-solvents usage. It involves a mechanical deconstruction of microcrystalline cellulose (MCC) into nanoscale particles in water and polyol through scalable bead-milling, vacuum drying, and followed by twin-screw reactive extrusion with isocyanate and chain extender. The thermal stability of CNC was higher than that of typically acidhydrolyzed CNC and suitable for processing with the precursors of TPU at typical processing temperature range (175-190 C). The CNC incorporation at very low loadings (0.5, 0.8 wt%) through this methodology resulted in substantial enhancements in tensile properties (for example, up to 28% in strength and toughness) without any significant stiffening effect. Moreover, the nanocomposites retained elastic properties, including elongation at break (%), resilience, and creep resistance. Their chemical properties and thermal transitions were also found to support the retained thermoplastic behavior while improving mechanical performance.

Highly Ordered Thermoplastic Polyurethane/Aramid Nanofiber Conductive Foams Modulated by Kevlar Polyanion for Piezoresistive Sensing and Electromagnetic Interference Shielding

“…Specifically, free and hydrogen-bonded C = O appeared in 1733 and 1704 cm −1 in Fig. 4 b is utilized to calculate hydrogen bonding index of C = O for the evaluation of microphase separation [ 58 , 59 ]. According to the increased peak intensity at 1733 and 1704 cm −1 with the increasing of Kevlar polyanion, the as-obtained ANF promotes the generation of hydrogen bonds in the hard domains, which resulted in a significant phase separation between the hard and soft domains of TPU by the degree of phase separation (DSP) [ 60 ], as shown in Table S1.…”

Effect of fillers on the microphase separation in polyurethane composites: A review

“…Cellulose is one of the richest natural polymers on earth; it is widely derived from natural plant fibers and has the advantages of renewable, biodegradable, and good biocompatibility. [71][72][73][74][75] CNC has excellent mechanical properties, high aspect ratio, low density, high specific strength, and low thermal expansion coefficient; it has been incorporated into a wide range of polymer matrices as reinforcing filler. 42,[76][77][78][79][80] In the study of Tian et al, 81 introduced urea groups ( NH CO NH ) into CNC surface.…”