Effect of Silica Sol-Modified Nano-Calcium Carbonate on Polyurethane(Urea) Dispersions and Their Films

A series of novel aqueous polyurethane(urea) (PUU)/silica sol-modified nano-calcium carbonate (CaCO3) hybrid dispersions were prepared using an in situ dispersion technique. Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) examinations indicated that the modified nano-CaCO3 particles were mostly covered or partially inlaid on the surface of PUU particles or in the PUU matrix. PUU/modified nano-CaCO3 hybrid dispersions with lower modified nano-CaCO3 content (<= 15%) exhibited low viscosity, small particle size and excellent stability. The rheological features revealed that this hybrid PUU dispersion belonged to pseudoplastic fluids. In addition, the incorporation of modified nano-CaCO3 could also enhance the mechanical properties of PUUs dramatically through the reinforcing effect of inorganic CaCO3. The better water resistance of PUU/modified nano-CaCO3 hybrid films proved that modified nano-CaCO3 could be used as effective modifiers for PUUs, and this method provided an efficient way to incorporate silica sol-modified nano-CaCO3 in the PUU matrix.