Effect of Alkali Pretreatment on Selective Oxidation of Cotton Fiber by Sodium Periodate

摘要

The contrast of the structure and properties of cotton fiber with or without alkali pretreatment oxidised selectively by sodium periodate was carried out. The results showed that the cellulose crystals were gradually transformed from cellulose Ⅰ to cellulose Ⅱ as alkali treatment concentration range from 5wt% to 25wt%, and alkali pretreatment led to decrystallinity, which can improve the reactivity of cotton fiber with sodium periodate and increase in aldehyde content. In the same oxidation process, the increasing of alkali concentration enhanced the degradation of the crystalline region of the oxidized samples. However, proper alkali pretreatment can reduce the degradation of modified cotton fiber resulted from increasing oxidant concentration up to 32g/l, which possibly dues to formation of more hemiacetal structure and improving intermolecular hydrogen bonding in oxidant reaction after sodium hydroxide treatment, leading to enhancement the ordered structure. Meanwhile, the breaking elongation of oxidized samples rapidly improved when increasing the alkali concentration above 10% at the same oxidation condition while the breaking strengthen of oxidized samples changed a little with increasing alkali concentration.