Self-assembly and Crystallization of Double Crystalline Aliphatic Thermoplastic Biopolyurethane and Its Nucleation with Cellulose Nanocrystals

An aliphatic segmented thermoplastic biopolyurethane (STPU), based on aliphatic hexamethylene diisocyanate (HDI) and 1,3 propanediol (1,3PD) as urethane rich phase and a poly(sebacate) as a macrodiol phase, with ~50 wt% of renewable carbon content, was synthetized and mixed with cellulose nanocrystals (CNC) to develop new bionanocomposites. The phase behaviour of the STPU and derived bionanocomposites was analyzed with a variety of techniques which include differential scanning calorimetry (DSC), isothermal crystallization, X-ray scattering and atomic force microscopy (AFM). The Isothermal crystallization of the STPU matrix allowed fitting to the Lauritzen-Hofmann model and calculation of the overall crystallization constant, K-g(tau). Further dynamic thermal analysis by X-ray scattering and DSC allowed the determination of the impact of CNC on the morphology and nucleation of the urethane rich phase. Self-nucleation experiments with the STPU matrix allowed quantification of the nucleation effect of the CNC.