Cellulose regenerated films obtained from the dissolution of cotton waste in ionic liquid

In this study, cotton waste (white and green) from the textile brushing process and cotton wool were used as raw materials to obtain regenerated cellulose films. Cellulose was dissolved with the ionic liquid 1-ethyl-3-methylimidazolium chloride [EMIM]Cl at temperatures of 110, 120, and 130 °C. The dissolution process was evaluated by polarized light microscopy which demonstrated that at lower temperatures (110 °C and 120 °C), the dissolution is preceded by swelling, whereas at 130 °C, rapid fragmentation of the fibers occurs. The presence of dye in cotton fiber extended the dissolution time. After dissolution at 110 °C and regeneration in a water bath, the films obtained were smooth and homogeneous and preserved the color of the residue. Characterization by X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FTIR) indicated a transition from crystalline type I cellulose in the cotton samples to an amorphous structure in the regenerated films. The thermogravimetric analysis (TGA) revealed that films showed lower thermal stability than cotton fibers, attributed to cellulose depolymerization. The cotton source did not significantly affect the mechanical properties of the films, which had tensile strength ranging from 25.8 to 33.4 MPa and elongation at break between 14.7 and 19.7%. Overall, textile residues can be used without prior treatment to produce either transparent or intrinsically colored films with potential for application in various fields. Graphical abstract