Hydrothermally induced changes in the properties of MFC and characterization of the low molar mass degradation products

Abstract

The aim of this study was to determine hydrothermally induced changes in the physicochemical properties of a fine microfibrillated cellulose (MFC). The MFC was prepared from a monocomponent endoglucanase-treated never-dried birch kraft pulp which had been run several times through a microfluidizer in order to obtain a sample substantially free from fibers or fiber fragments. The fine MFC was subjected to hydrothermal treatment at 150 C for 0.5, 2.5, 4.5, 8.5 and 20.5 h, after which the viscosity, water-retention capacity, surface charge, discoloration and formation of hydrolysis products were determined. The viscosity, surface charge and waterretention capacity of MFC decreased as a result of the treatment but in oscillatory measurements the storage and loss moduli increased. Hydrothermal treatment also caused discoloration of the sample which could not be fully washed away with water. Surface analysis with XPS revealed no significant changes in the surface structure of the dried MFC cakes but the filtrates after the hydrothermal treatment were complex mixtures of sugars, organic acids and furans. The main degradation products detected were xylose and xylobiose, but isomerization products of sugars (xylulose, fructose) were also found in the filtrates. In addition numerous organic acids, including formic, glycolic, lactic and xylonic acid, were identified in the filtrates, showing that both acid and alkaline catalyzed reactions occur due to dissociation of water into H þ and OH À .

Preparation of Aramid–Cellulose Nanofiber Films with Improved Mechanical and Dielectric Properties Utilizing Environmentally Friendly Hydrothermal Treatment for Electrical Insulation

“…The hydrogen bonding between the two fibers can be attributed to this band broadening. The intensity is reduced due to cellulose dehydration during the hydrothermal treatment and a lower CNF content in the film . The NH stretching and amide I of ANFs lead to peaks at 3315, 1600, and 1642 cm –1 .…”

“…The intensity is reduced due to cellulose dehydration during the hydrothermal treatment and a lower CNF content in the film. 25 The NH stretching and amide I of ANFs lead to peaks at 3315, 1600, and 1642 cm −1 . The peaks caused by an asymmetric stretching of the cellulose's pyranose ring skeleton shifted from 1160 and 1105 to 1164 and 1110.7 cm −1 , respectively.…”