Determining slenderization of wood pulp

Researchers from the Institute of Scientific and Industrial Research at Osaka University have devised a new method to determine the degree of fibrillation in wood crushing. By taking advantage of cellulose innate birefringence, they were able to measure the morphology change through optical delay rotation. This work could lead to a clear ranking and smart use of renewable biofuels, cellulose nanofibers.

Cellulose, a major structural component of most plants, has been harvested by humanity for thousands of years as an important biomaterial for clothing, paper, and wood structures. Recently, cellulose nanofibers, which have the benefit of various functions derived from the expanded chain crystals that make up cellulose, have been developed, including optical birefringence. Conferences occur when the effective speed of light within a material depends on polarization; in this case, whether the polar light is parallel or perpendicular to the polymer chains.

Now, a team of scientists at Osaka University has developed an optical analysis system that can directly measure the degree of fibrillation of wood pumps. Fibrillation is the process of reducing the bundling of cellulose molecules in micro-scale fibers to form nanoscale fibers. Compared to carefully measuring the widths of a fiber with an electronic microscope, this method quickly and easily determines whether the cellulose fibers are aligned or scattered in random directions. “Our system offers clear and measurable criteria for ranking the quality of cellulose nanofibers,” says first author Kojiro Uetani.

This is achieved by monitoring cellulose fibers in a quartz flow cell with a birefringence microscope. The sample is illuminated from below by a circular polarized light, which has an electric field direction that orbits the space like a helix. Sections of the fibers with high birefringence cause a greater optical delay in the level of light. Using a birefringence microscope, the researchers were able to record this value pixel-by-pixel. They found that both the average eye delay and the general deviation were related to the degree of fibrillation. High delay values ​​were associated with incomplete pulp fibers, while smaller values ​​were observed with a balloon-like structure in fibrillating crushing, and very small values ​​occurred with dispersed nanofibers.

“We hope to promote precise structure control and advanced use of wood pulp and cellulose nanofibers,” says lead author Masaya Nogi. In addition to the results of the article described above, the team has also proven that it is possible to automatically determine the degree of fibrillation of unknown pulp samples by learning in depth about delay images. This system is expected to lead to a clearer and more automated explanation of the rate of artificial intelligence (AI) fibrillation in the future and will be a key analytical technology for identifying the quality of pulp materials and nanofibers cellulose.