Preparation and Characterization of Cellulose Nanofibril-Waterborne Polyurethane Composite Films

Abstract

To improve the performance of polyurethane films, small amounts of cellulose nanofibrils (CNF) were physically blended with a waterborne polyurethane (WPU) emulsion, and then CNF/WPU composite films were prepared by cast-coating and drying. The particle size of the emulsions and the chemical structure, micromorphology, thermal stability, mechanical properties, and water resistance of the composite films were characterized using a Malvern laser particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), an electronic strength machine, water contact angle analysis (WCA), and water absorption tests, respectively. The results showed that at a low CNF content of 0.3 wt% , the particle size of the WPU emulsion and chemical structure of the film did not change significantly. In addition, the tensile strength of the composite film increased by up to 108% compared to the neat WPU film, and the thermal stability and water resistance were slightly improved. The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film, which may greatly improve the service life and tear resistance of commercial coatings in the future.

Fabrication of Waterborne Silicone-Modified Polyurethane Nanofibers for Nonfluorine Elastic Waterproof and Breathable Membranes

“…The hot-pressing treatment further reduced the size of pores, resulting in the excellent waterproof performance of the membrane. The experimental results showed that the prepared WE PUSX-CP-2 membrane had high hydrophobicity (137.9°), significantly surpassing conventional waterborne polyurethane nanofibers (usually < 90°) [ 51 , 52 ]. The hydrostatic pressure of the membrane was 51.5 kPa, and the WVT rate was 5476 g m −2 d −1 , which was comparable to that of organic solvent-based nanofiber WBMs [ 19 , 53 , 54 , 55 , 56 ].…”

Comparison of Nanofibrillated Cellulose and Hydroxyethyl Cellulose in Improving the Storage Stability of Waterborne Coatings

“…Nanofibrillated cellulose (NFC) is commonly used as reinforcing agent [13][14][15] because of its nanoscale size, large aspect ratio, abundant surface hydroxyl groups, and high strength. To construct a fiber network structure through physical entanglement and hydrogen bonding in solution may improve storage stability without significantly increasing the viscosity of the waterborne coatings [16][17][18] . Furthermore, this may hinder the settling of colored particles.…”