Iα → Iβ transition of cellulose under ultrasonic radiation

Aqueous suspensions of dispersed Glaucocystis cellulose microfibrils were sonicated at 4 A degrees C for 3 h, using 24 kHz ultrasonic waves. This treatment induced a variety of ultrastructural defects, as the microfibrils became not only shortened, but also presented substantial damage materialized by kinks and subfibrillation. Upon analysis by X-ray diffraction and C-13 solid-state NMR spectroscopy, it was found that the initial sample that contained 90 % of cellulose I-alpha allomorph became, to a large extent, unexpectedly converted into the I-beta phase, while the loss of crystallinity was only moderate during the sonication treatment.