Bastida Gabriela Adriana, Schnell Carla Natalí, Mocchiutti Paulina, Solier Yamil Nahún, Inalbon María Cristina, Zanuttini Miguel Ángel, Galván María Verónica
Institute of Cellulosic Technology, Faculty of Chemical Engineering (FIQ-CONICET), National University of the Litoral, Santiago del Estero 2654, Santa Fe S3000AOJ, Argentina.
Nanomaterials (Basel). 2022 Aug 24;12(17):2908. doi: 10.3390/nano12172908.
The present work analyzes the effect of process variables and the method of characterization of cellulose micro/nanofibers (CMNFs) obtained by different treatments. A chemical pre-treatment was performed using oxalic acid at 25 wt.% and 50 wt.%. Moreover, for mechanical pre-treatments, a rotary homogenizer or a PFI mill refiner were considered. For the mechanical fibrillation to obtain CMNFs, 5 and 15 passes through a pressurized homogenization were considered. The best results of nanofibrillation yield (76.5%), transmittance (72.1%) and surface charges (71.0 µeq/g CMNF) were obtained using the PFI mill refiner, 50 wt.% oxalic acid and 15 passes. Nevertheless, the highest aspect ratio (length/diameter) determined by Transmission Electron Microscopy (TEM) was found using the PFI mill refiner and 25 wt.% oxalic acid treatment. The aspect ratio was related to the gel point and intrinsic viscosity of CMNF suspensions. The values estimated for gel point agree with those determined by TEM. Moreover, a strong relationship between the intrinsic viscosity [η] of the CMNF dispersions and the corresponding aspect ratio (p) was found (ρ[η] = 0.014 p, R = 0.99). Finally, the tensile strength of films obtained from CMNF suspensions was more influenced by the nanofibrillation yield than their aspect ratio.
本工作分析了工艺变量以及通过不同处理获得的纤维素微/纳米纤维（CMNFs）的表征方法的影响。使用25 wt.% 和50 wt.% 的草酸进行化学预处理。此外，对于机械预处理，考虑了旋转均质器或PFI磨浆机磨浆机。为了通过机械原纤化获得CMNFs，考虑了5次和15次通过加压均质化。使用PFI磨浆机磨浆机、50 wt.% 的草酸和15次通过，获得了纳米原纤化产率（76.5%）、透光率（72.1%）和表面电荷（71.0 µeq/g CMNF）的最佳结果。然而，使用PFI磨浆机磨浆机和25 wt.% 的草酸处理，通过透射电子显微镜（TEM）测定的长径比（长度/直径）最高。长径比与CMNF悬浮液的凝胶点和特性粘度有关。凝胶点的估计值与通过TEM测定的值一致。此外，发现CMNF分散体的特性粘度[η]与相应的长径比（p）之间存在很强的关系（ρ[η] = 0.014 p，R = 0.99）。最后，由CMNF悬浮液制成的薄膜的拉伸强度受纳米原纤化产率的影响大于其长径比。
