Reyes Guillermo, Ajdary Rubina, Kankuri Esko, Kaschuk Joice J, Kosonen Harri, Rojas Orlando J
Biobased Colloids and Materials, Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Espoo, Finland.
Biobased Colloids and Materials, Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Espoo, Finland; Bioproducts Institute, Department of Chemical & Biological Engineering, Department of Chemistry and Department of Wood Science, 2360 East Mall, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Carbohydr Polym. 2023 Feb 15;302:120355. doi: 10.1016/j.carbpol.2022.120355. Epub 2022 Nov 23.
We address the limited solubility and early onset of gelation of aqueous sodium hydroxide to position it as a preferred green solvent for cellulose. For this purpose, we expand the concentration window (up to 12 wt%) by using a CO-depleted air and adjusting the time the dope remains in the given atmosphere, before further processing (holding time) and regeneration conditions. Cellulose solutions are extruded following characteristic (rheology and extrusion) parameters to yield aligned filaments reaching tenacities up to 2.3 cN·dtex, similar to that of viscose. Further material demonstrations are achieved by direct ink writing of auxetic biomedical meshes (Poisson's ratio of -0.2, tensile strength of 115 kPa) and transparent films, which achieved a tensile strength and toughness of 47 MPa and 590 kJ·m, respectively. The results suggest an excellent outlook for cellulose transformation into bioproducts. Key to this development is the control of the gelation ensuing solution flow and polymer alignment, which depend on CO absorption, cellulose concentration, and holding time.
我们针对氢氧化钠水溶液溶解度有限和凝胶化过早的问题，将其定位为纤维素首选的绿色溶剂。为此，我们通过使用贫一氧化碳空气并调整纺丝原液在给定气氛中停留的时间（即保持时间）以及再生条件，来扩大浓度窗口（高达12 wt%）。按照特征（流变学和挤出）参数挤出纤维素溶液，以生产出取向丝，其强度高达2.3 cN·dtex，与粘胶纤维相似。通过直接墨水书写负泊松比生物医学网（泊松比为 -0.2，拉伸强度为115 kPa）和透明薄膜，实现了进一步的材料展示，其拉伸强度和韧性分别达到47 MPa和590 kJ·m。结果表明纤维素转化为生物产品前景广阔。这一发展的关键在于控制凝胶化过程中随之而来的溶液流动和聚合物取向，这取决于一氧化碳吸收、纤维素浓度和保持时间。
