关键词: 微晶纤维素, 超声波处理, 碱润胀, 氧化纤维素

Abstract: Ultrasound treatment and alkali swelling were applied to activate microcrystalline cellulose (MCC) in order to improve its reactivity performance. Changes in supramolecular structure and physical characteristics among MCC after activation were compared. The influences of ultrasound treatment and alkali swelling on oxidation reactivity of MCC were investigated in the presence of sodium periodate. The mechanism of the change of reactivity after activation was discussed. The results showed that the type of MCC crystal was not changed and the size of crystalline was almost not changed after ultrasound treatment. However, after ultrasound treatment crystallinity of MCC was decreased and hydrogen bonds among MCC molecules were destroyed. MCC particles were broken into small particles and the surface was damaged. These changes are attributed to the increases of accessibility and specific surface area of MCC with an improvement on reactivity. The type of MCC crystal after alkali swelling was changed to the mixture of typesⅠandⅡ. The size of MCC crystal was decreased while specific surface area was increased remarkably through decrystallization by alkali swelling. Furthermore, aldehyde content of dialdehyde cellulose (DAC) was improved from 71.3 to 85.0% and 88.8% respectively by activation of ultrasound treatment and alkali swelling, indicating an improvement of regioselective oxidation reactivity of MCC in the presence of sodium periodate.

Key words: microcrystalline cellulose, ultrasound treatment, alkali swelling, dialdehyde cellulose