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UBC Theses and Dissertations
Studies of the nitration of cellulose - application in new membrane materials Cheung, Clement
Since the discovery of the production of nanocrystalline cellulose (NCC) from acid hydrolysis of bulk cellulose, this material has been used as a template for imparting photonic properties on materials without innate structural ordering and as an additive in polymer composites to increase structural strength. However, the potential of NCC as a feedstock for highly nitrated cellulose has not been investigated. It is postulated that the smaller chain lengths in NCC may permit a higher degree of nitration in comparison with conventional nitrocellulose. In this thesis, various nitration methods have been investigated for their ability to produce highly nitrated NCC. Traditional nitration methods using HNO₃/H₂SO₄ and less common nitration methods using HNO₃/P₂O₅ and HNO₃/Ac₂O were used and the differences between methods were studied. There was an effect in using H₂SO₄ as the desiccant on the hindrance of the degree of nitration. Titration of the nitrated material with base shows the presence of more sulfate groups in samples nitrated in the presence of H₂SO₄ than in the absence of it, demonstrating that H₂SO₄ is a less ideal desiccant. In addition, pretreatment of NCC with a desulfation procedure improved the degree of nitration. The investigation of the other desiccants showed the importance of using a miscible, non-degrading desiccant to obtain a high degree of nitration. The synthesized nitrated nanocrystalline cellulose, hereby abbreviated as NNC, were analyzed by elemental analysis for the nitrogen content, powder X-ray diffraction for crystallinity, Fourier-transform infrared spectroscopy and thermal gravimetric analysis for the stability of the compound.
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