Deformation of Cotton and Bacterial Cellulose Microfibrils

The morphology and substructure of cotton and bacterial cellulose microfibrils have been studied in the electron micro scope following deformation by ultrasonication and by stretching on a Mylar substrate. Cotton microfibrils, which have an average width of about 250Å, were shown by negative staining to be broken down by ultrasonication into "elementary fibrils" with a width of ∼35Å. Bacterial cellulose microfibrils ranged in width from 140-200Å; the 140Å width is thought to represent the best packing of the elementary fibrils in the microfibril. Elementary fibrils were observed at bends and kinks in the unsonicated microfibrils. The results for microfibrils from both sources which had been deformed by stretch ing on Mylar were consistent with complete breakdown into elementary fibrils, similar to previous reports of deformation for Valonia cellulose.