Cellulose ( IF 4.9 ) Pub Date : 2021-09-08 , DOI: 10.1007/s10570-021-04151-8 Shin Young Park 1 , Sooim Goo 2 , Jinseung Kim 2 , Hye Jung Youn 2, 3, 4 , Heenae Shin 3
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Porous cellulose nanofibril (CNF) foam was prepared by stabilizing bubbles with CNF and a surfactant and then drying the stabilized wet foam in a convection oven. The consistency of carboxymethylated CNF (CMCNF) and the addition amount of the surfactant were controlled and the effects of these factors on the CNF wet foam and dry foam properties were investigated. An adequate amount of the surfactant (0.02–0.04 wt%) with CMCNF consistency higher than 0.5 wt% yielded wet foams with excellent stability. When the wet foam was dried at 60 °C in an oven, dry CNF foam with over 97% porosity was generated. The stable wet foams resulted in dry CNF foam with a sphere-like pore structure and low levels of shrinkage during drying. In contrast, unstable wet foams generated dry foam with severe shrinkage and large cavities. The pore size and the porosity of the dried foam were determined by the shape of bubbles in the wet foam and the degree of shrinkage during drying, which, in turn, affected the mechanical strength. In addition, the compressive strength of the oven-dried foam was 83% higher than that of the freeze-dried foam. Therefore, the preparation of a stable wet porous CMCNF foam by controlling the CMCNF consistency and the amount of surfactant was essential for obtaining a porous CMCNF foam with a uniform pore structure and good mechanical strength by oven drying.
Graphic abstract
中文翻译：
纤维素纳米纤维泡沫的结构特性取决于 Pickering 稳定中的湿发泡条件
通过用 CNF 和表面活性剂稳定气泡，然后在对流烘箱中干燥稳定的湿泡沫，制备多孔纤维素纳米纤维 (CNF) 泡沫。控制羧甲基化CNF（CMCNF）的稠度和表面活性剂的添加量，研究这些因素对CNF湿泡和干泡性能的影响。足量的表面活性剂 (0.02-0.04 wt%) 和 CMCNF 稠度高于 0.5 wt% 产生具有优异稳定性的湿泡沫。当湿泡沫在烘箱中在 60°C 下干燥时，生成孔隙率超过 97% 的干燥 CNF 泡沫。稳定的湿泡沫导致干燥的 CNF 泡沫具有球形孔结构和干燥过程中低水平的收缩。相比之下，不稳定的湿泡沫产生具有严重收缩和大空腔的干泡沫。干燥泡沫的孔径和孔隙率由湿泡沫中气泡的形状和干燥过程中的收缩程度决定，进而影响机械强度。此外，烘箱干燥泡沫的抗压强度比冻干泡沫高83%。因此，通过控制 CMCNF 的稠度和表面活性剂的量来制备稳定的湿多孔 CMCNF 泡沫对于通过烘箱干燥获得具有均匀孔结构和良好机械强度的多孔 CMCNF 泡沫至关重要。
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