Abstract: Microwave-assisted alkali treatment was applied to pretreatment of secondary fiber(SF) to improve its reactivity. The changes of chemical composition, supramolecular structure and physical characteristics of SF after activation were studied. The mechanism of microwave-assisted alkali pretreatment of secondary fiber(WASF) was discussed. The results showed that crystal form of SF was not changed, but the crystallinity of SF was decreased, hydrogen bonds among SF molecules were partially destroyed, fiber surface was damaged. These changes resulted in the increases of accessibility, specific surface area and reactivity of SF. Under similar microwave irradiation power, prolonging of irradiation time is beneficial to cyanoethylation of SF. Furthermore, nitrogen content of cyanoethylated SF was improved from 10.85% to 17.80%.

Key words: secondary fiber, alkali pretreatment, microwave-assisted alkali pretreatment, cyanoethylation