Water-Based Approach to High-Strength All-Cellulose Material with Optical Transparency

All-cellulose composites are usually prepared by a partial cellulose dissolution approach, using of ionic liquids or organic solvents. Here, an all-cellulose film based on moist ramie fibers was prepared by hot-pressing. The original ramie fiber was degummed, alkali treated, aligned, and mounted into a specially designed mold. The wet ramie fiber cake was pressed into a transparent film. The structure, mechanical properties, moisture sorption, and optical properties of the films were investigated using scanning electron microscopy (SEM), X-ray diffraction, tensile tests, gravimetric method, and integrating sphere devices. The all-cellulose films showed an ultimate strength of 620 MPa and a Young's modulus of 39.7 GPa with low moisture sorption and optical transmittance of 85%. These eco-friendly all-cellulose films are of interest for laminated composites, as coatings and in photonics applications.