Biodegradation Of Cellulose Acetate Fiber

Cellulose acetate fiber is the second important cellulose fiber, only next to the viscose fiber. With good physical properties and advantages of both natural (including artificial fiber) and synthetic fibers, cellulose acetate fiber is widely used in the industrial fields such as materials of cigarette filter, textile and garments, medical and health products. However, because of the acetylation of hydroxyl on the cellulose molecules, cellulose acetate fiber has a stable property and is hardly to be biodegraded, causing great pollution to the environment.Biodegradation has many features including mild condition, high selectivity and specificity, eco-friendly and safe for use. To hydrolyse the ester bonds and improve the biodegradability of cellulose acetate, lipase, cutinase and cutinase with cellulose binding domain (CBD) were used, and the effects of sodium hydroxide pretreatment and electron beam irradiation pretreatment on the structure, properties and biodegradability of cellulose acetate fiber were also studied.The results showed that the esterase (lipase, cutinase enzyme and CBD-cutinase) could catalyze the hydrolysis of cellulose acetate and improve the moisture absorption and dyeability of the fibers. However, as a kind of protein with high molecular weight and large volume, it is hard for enzyme to penetrate the fiber's compact surface and spread to fiber interior, so the enzymatic hydrolysis are only limited to the fiber surface, which results in a very small change in degree substitution.Sodium hydroxide can hydrolysis ester bonds of cellulose acetate fiber, reduce the substitution degree and improve the hydrolysis activity of esterase to the ester bonds of cellulose acetate, especially for the CBD-cutinase. The activity of the enzyme to hydrolyse cellulose acetate pretreated with 0.05 mol/L sodium hydroxide follows the order: lipase > cutinase > CBD-cutinase , and using esterase and cellulase in one bath was better than use esterase and cellulase respectively.The scanning electron microscopy (SEM), infrared spectroscopy and the viscosity testing proved that electron beam irradiation pretreatment could etch the surface of cellulose acetate fiber, break up the molecular chains, reduce the degree of polymerization, and improve the degradability of cellulose acetate treated with esterase and cellulase. And the higher the radiation dose was applied, the better the biodegradability of the treated cellulose acetate fiber.