Enhanced Morphological Characterization of Cellulose Nano/Microfibers through Image Skeleton Analysis

Abstract

The present paper proposes a novel approach for the morphological characterization of cellulose nano and microfibers suspensions (CMF/CNFs) based on the analysis of eroded CMF/CNF microscopy images. This approach offers a detailed morphological characterization and quantification of the micro and nanofibers networks present in the product, which allows the mode of fibrillation associated to the different CMF/CNF extraction conditions to be discerned. This information is needed to control CMF/CNF quality during industrial production. Five cellulose raw materials, from wood and non-wood sources, were subjected to mechanical, enzymatic, and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-mediated oxidative pre-treatments followed by different homogenization sequences to obtain products of different morphologies. Skeleton analysis of microscopy images provided in-depth morphological information of CMF/CNFs that, complemented with aspect ratio information, estimated from gel point data, allowed the quantification of: (i) fibers peeling after mechanical pretreatment; (ii) fibers shortening induced by enzymes, and (iii) CMF/CNF entanglement from TEMPO-mediated oxidation. Being mostly based on optical microscopy and image analysis, the present method is easy to implement at industrial scale as a tool to monitor and control CMF/CNF quality and homogeneity

This research was funded by the Spanish Ministry of Economy and Competitiveness for the funding of the projects CTQ2017-85654-C2-1-R and CTQ2017-85654-C2-2-R and the Community of Madrid via funding of RETO-PROSOST-2-CM (S2018/EMT4459), as well as the Universidad Complutense de Madrid and Banco de Santander via the grant of J.L. Sanchez-Salvador (CT17/17). Thanks also go to the Spanish Ministry of Science and Innovation for the Juan de la Cierva aid of Cristina Campano (Ref. FJC2019-040298-I). Marc Delgado-Aguilar is a Serra Húnter Fellow