Disintegration of cellulose into nanocellulose (NC) could improve processibility and product performance. Cast-film preparation and physiochemical properties have been investigated using different NCs prepared from different cellulose sources after different preparation processes in order to reveal the dependence of the film forming and performance on the NC’s chemical and physical structures. The NCs applied were prepared from tunicate (TNC), softwood (SWNC) or hardwood (HWNC) cellulose by conducting an identical homogenization treatment after either enzymatic hydrolysis or TEMPO-mediated oxidation. It has been found that the obtained NCs show a large diversity in terms of chemical composition, degree of polymerization (DP), crystallinity index (CI), fibrils size, aspect ratio, and chemical charge. These differences have significant impacts on the morphology, optical properties, mechanical property, thermal stability and hydrophilicity of the cast-films. For example, more microfibrillar aggregates are observed for woody NCs while TNC is dominant by individual fibrils. TNC is very pure (purity&gt;99%) but both hemicellulose and lignin are present in SWNC and HWNC. TNC is in a sharp contrast to the woody NCs with higher DP, larger aspect ratio and higher CI with more pure I<sub>β</sub> crystalline. These differences result in lower hydrophilicity, better mechanical properties and higher thermal stability of the obtained TNC cast-film. However, the woody films are more transparent. TEMPO-mediated oxidation introduces charged carboxyl groups making the cast-films much denser and smoother than the enzymatic hydrolyzed NC films. However, the oxidation deteriorates the thermal stability and hydrophobicity. Lignin correlates to low hydrophilicity and high UV-barrier property while hemicellulose is responsible for improved film flexibility but lower hydrophobicity and poorer thermal stability. Having more glucomannan than xylan, the SWNC films show higher thermal stability than HWNC ones. Moreover, the former have stronger mechanical strengths than the latter. Meanwhile, the relatively higher content of rigid lignin structures present in latter is another reason for the lower mechanical properties. These direct comparisons conducted in this study among different NCs and their cast-films will provide useful information and knowledge for the applications of tunicate and woody cellulose or NCs for various bio-based material preparations.

Film formation and performance of different nanocelluloses obtained from different cellulose sources after different preparation processes

253rd National Meeting (2017)

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