Properties of films prepared from steam exploded softwood cellulose

Regenerated cellulose (RC) films were prepared from the cellulose solution that was obtained by directly dissolving wet steam exploded softwood cellulose (SESC) in 9.5% NaOH/1.0% urea aqueous solution using 2%-25% H₂SO₄ as the coagulant. Various properties of RC films were evaluated by X-ray diffraction, FTIR, SEM and tensile test. SESC occurred as the transform of its crystalline form Cell-I to Cell-II in the process of film formation. The inner structure of the film can be adjusted by altering the concentration of the coagulant, while the surface layer of the film proved to be more porous than the inner structure. 5% H₂SO₄ appeared to be the optimal coagulant for preparing the RC film having a maximum tensile strength (88.7 MPa) and elongation at break (4.1%).