執行成果摘要
In the year, we completed the preparations of 6 algal nanocrystalline celluloses using the TEMPO oxidation treatment and evaluated their physical properties. With respect to the particle size distribution, laser scattering analyzer indicated that the nanocelluloses had particle diameters between 35.7 to 384.0 nm which complied with the definition of a nanomaterial. In addition, of the freeze-dried and nonfreeze-dried algal nanocelluloses, the former had larger particle sizes than the latter, suggesting that freeze-dried algal nanocelluloses had tendency of reaggregating upon rewetting. Scanning and transmitting electron microscopy observations of the cellulose preparations indicated that SEM was not suitable to provide clear images while TEM was a better method for observing minute structure of the samples. Wide-angle X-ray diffraction analyses of the 6 algal nanocellulose suggested that after TEMPO oxidation, the major 2qo diffraction peaks of the holocellulose tended to disappear. This was deemed to be caused by severe degradation of the crystalline regions of the cellulose after TEMPO oxidation. Total attenuation FTIR (FTIR-ATR) analyses of the samples indicated that all the samples produced peaks at ca. 1740 cm-1, which suggested that TEMPO oxidation modified the celluloses, creating carboxylic (COOH) groups at the C6 hydroxyl, and the C=O stretch had peaks at 1740 cm-1. Nnanocellulose preparation from Chlorella pyrenoidosa when added to paper handsheets increased its tensile, tear, burst, folding endurance and zero-span tensile strengths by as much as 91%, 71%, 128%, 76%, and 39%, respectively. Thus, the preparation showed a great potential as a strengthening agent for paper and as special functional paper ingredient.