Cellulose, one of the main constituents of the cotton fiber, is a polymer composed of glucose units that are linked by β-1, 4-glycosidic bonds to form a linear polymeric chain. Due to cellulose chemical properties, there is a high demand for its derivatives, cellulose acetate, and viscose rayon in the textile industry. Cellulose acetate is semisynthetic cellulose obtained through the acetylation process where the viscose rayon has a lower polymerization. The main goal of this project is to investigate the chemistry behind the dyeing process of cellulose, cellulose acetate, and viscose rayon fabric with a natural dyeing agent, carminic acid extracted from an insect, cochineal. The bonding of a dye to fabric is heavily relied on what type of chemical structure the dye possesses, and the molecules that are present in the fabric. Carminic acid molecules contain many hydroxyl –OH groups in the structure and attached with the cellulose fibers through hydrogen bonds during the dying process. The binding properties of cotton, cellulose acetate, and viscose rayon fabrics with carminic acid at different temperatures and pH levels and with various mordants were investigated. In addition, the de-acetylation reaction of cellulose acetate was studied, and the de-acetylation process increased the binding properties with cochineal natural dye.

Investigation of intermolecular forces between cochineal dye used for dyeing cellulose and cellulose derivatives

ACS Spring 2022

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