| Abstract: | Structure and time evolution of a nascent cellulose sheet, produced by Acetobacter xylinum, were examined regarding the resistance of the nascent fibrils to alkali. It became clear that the never-air-dried cellulose, obtained after an incubation period of 5 min, changes its morphology after an alkali treatment at very low concentrations (ranging from 1,0 · 10?3 to 1,0 · 10?2 wt.-%). It is subsequently transformed into cellulose II. On the other hand, although the fibril after an incubation period of 30 min seems to be in a stainable state toward sodium tungstophosphate when it was treated with 4,6 wt.-% alkali, 70–80% of it maintains the fibrous shape. Electron diffraction experiments, involving the fibrils, indicate a cellulose I structure. Even when the sample after an incubation period of 30 min was treated with 9,6 wt.-% alkali, about 30% of it still maintains the fibrous shape. Electron diffraction experiments, involving the fibrils, also indicate a cellulose I structure. The shape of a cellulose sheet, just after its extrusion from a cell, seems to be maintained by hydrophobic bonds. The enhancement of the resistance of cellulose toward alkali with time must be due to the development of inter-and intramolecular hydrogen bonds in each cellulose sheet. |
