From elastomeric to rigid polyurethane/cellulose nanocrystal bionanocomposites

Bionanocomposites with high content of carbon coming from renewable resources were synthesized. Different cellulose nanocrystal (CNC) contents were added by solvent casting procedure to highly crystalline bio-based polyurethanes with different soft/hard segment ratios. Properties of the resulting bionanocomposites were evaluated in order to study the effect of both CNC content and polyurethane soft/hard segment ratio on the structure/properties relationships. Thereby, from elastomeric to rigid polyurethane/CNC bionanocomposites containing 1, 3, 5 and 10 wt% of CNC and bio-based polyurethanes with 17 and 46 wt% of hard segment content were prepared. CNC were isolated by sulphuric acid hydrolysis, obtaining rod-like crystalline structures. A good dispersion of CNC was obtained for all the bionanocomposites, which interact with the polyurethane segment that was not associated in ordered domains. Thermomechanical and tensile tests revealed that those bionanocomposites presented good mechanical properties, competing with petrochemical based nanocomposites.