The Structure And Properties Of Cellulose Fibers Treated With Ultrasonic Wave

Ultrasonic wave has been applied in the pretreatment of the fast-growing wood pulp cellulose fibers in order to increase the accessibility and reactivity of cellulose. A systematic study in different structure levels has originally been made on the changes of the morphology, supermolecular structure, and molecular weight and its distribution of cellulose brought about by ultrasonic treatment The accessibility of the cellulose fibers after it had been treated with ultrasonic characterized as water retention value and surface area has also been investigated. The selectively oxidation reactivity of the treated cellulose fibers with sodium periodic has been studied in detail. The tentative mechanism for the changes in structure and properties of cellulose fibers resulting from the ultrasonic treatment has been discussed. The main research aspects are as follows:1. The morphology and fine structure of cellulose fibers treated with ultrasonic have been characterized by polarized light microscopy and scanning electron microscopic observation. The fiber length and coarseness are analyzed. The results showed that the morphology and the fine structure of cellulose fibers have changed during the ultrasonic treatment. Rupture and removal of the P and S1 layer, dislocations in the S2 layer, swelling of the fiber, and then fibrillation in the S2 layer have been observed on ultrasonic treated cellulose fibers. It is showed that ultrasonic treatment has less effect on fiber length.2. The level of changes on fibers' morphology and fine structure is dependent on the raw fibers' morphology size and the ultrasonic treatment conditions such as treatment time, consistency of the slurry, and the power of ultrasonic wave. The experimental results on morphology and fine structure of the treated cellulose fibers indicate that (1) the morphology structure of bleached masson pine (MBKP) and eucalyptus Kraft pulp (EBKP) fiber is readily changed by ultrasonic treatment, and (2) the eucalyptus dissolving pulp (GCEP) cellulose fiber is more resistant to the ultrasonic treatment As the treatment time and ultrasonic power increased, the effectiveness of the treatment increases and there is a significant increase in fibrillation. The proper...