An alternative approach for the incorporation of cellulose nanocrystals in flexible polyurethane foams based on renewably sourced polyols

This work analyzes not only the effect of cellulose nanocrystals on final properties of castor oil and corn based flexible polyurethane foam nanocomposites but also a deep analysis about the changes on micro/nanostructure and morphology is carried out. Cellulose nanocrystals were isolated from microcrystalline cellulose by acid hydrolysis and incorporated in aqueous suspension to renewably sourced polyols for foam synthesis. The effect of cellulose nanocrystals percentage on cell morphology, nano/microstructure and properties of the foam nanocomposites was analyzed by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, compressive mechanical properties, hysteresis and resilience tests and dynamic mechanical analysis. To verify the presence of cellulose nanocrystals in the foam cell walls, infrared near-field microscopy and nanospectroscopy were employed. Results suggested that interactions between cellulose rianocrystals and polyurethane hard segments occurred and foam cell walls were reinforced. The overall reinforcing effect showed to be dependent on the cellular structure of the foam, which was in turn influenced by the presence of cellulose nanocrystals. (C) 2016 Elsevier B.V. All rights reserved.