Preparation and characterization of modified CNC/waterborne polyurethane composite film

To improve the water resistance and mechanical performance of waterborne polyurethane, modified cellulose nanocrystal (CNC) as a kind of environmentally friendly material was added into the solution of waterborne polyurethane by the in-situ polymerization and mechanical blending way, and two different modified CNC/waterborne polyurethane composite films were prepared. The results show that due to the addition of modified CNC, the composite film prepared by in-situ polymerization way showed much better behavior in both water resistance and mechanical properties than that made by the mechanical blending method. When the content of modified CNC was 5% in the composite, the water resistance of the composite film increased by 34.6%. At the same time, the tensile property of the composite film was improved when using in-situ polymerization to fabricate the film, and the value of maximum tensile stress rose by 143.9%.