Effects of orientation and degree of polymerization on tensile properties in the cellulose sheets using hierarchical structure of wood

Abstract

Structural control is essential for further development of cellulosic materials. Here, we demonstrated the significance of the orientation and degree of polymerization in the integrated structure of cellulose microfibrils using sheets based on the hierarchical structure of wood. Non-cellulosic components were removed from wood blocks of a conifer by applying a two-step chemical treatment. Partially changing the treatment conditions generated cellulose blocks with varying degrees of polymerization while maintaining the anatomical structure. Cellulose sheets with oriented microfibrils were subsequently prepared by heat-pressing the blocks. Sheets with randomized appearance of orientation were also produced by disassembling tracheid alignment. These sheets were then subjected to structural evaluation and tensile tests. Comparison of both sheets showed that microfibril orientation mainly determined the modulus. As long as the orientation was maintained, the specific modulus was independent of the degree of polymerization. In contrast, the tensile strength of the oriented sheet varied with the degree of polymerization, indicating that it notably reflected the single fiber strength compared to the randomly oriented sheet. Hence, a highly oriented structure with unfragmented microfibrils is the determinant of a superior material. Consequently, the sheets in which these parameters are readily controlled can advance cellulose applications.

An Oxidative Enzyme Boosting Mechanical and Optical Performance of Densified Wood Films

“…TEMPO‐mediated oxidation in neutral conditions has been shown to reduce the cellulose DP by 30%, [ 41 ] while the most severe chemical treatments cause up to 70% loss in the cellulose DP. [ 42 ] Even a rather mild alkaline sulfite‐anthraquinone‐methanol treatment causes 20%–40% loss in the cellulose DP. [ 30 ] Indeed, compared to the chemical treatments, the decrease in cellulose DP by the LPMO oxidation was modest.…”

Synthesis and Characterization of Mango Wood Nanocellulose Fibers

“…Even the tendency to agglomerate can be seen in all of the images. The IL-MWNC reveals nanofibers of the length of several microns and with an average diameter between 27.33 and 34.85 nm that are regularly organized and correlated with cellulose fibers [33,34]. This is inferred from the above observation that the synthesized nanocellulose well exhibits nanoscale dimensions.…”

Structural diversity of natural cellulose and related applications using delignified wood

“…The deuterated samples are then rehydrogenated by immersion in water at room temperature, whereby the deuterium atoms of all Fig. 2 Tensile stress-strain curves for an oriented sheet and a random sheet prepared by pressing colorless wood (reproduced from [72])…”