The influence of temperature and moisture on the physical properties of cellulose in the presence of metal chlorides and glucuronic acid

We investigated the influence of Mg2+, Ca2+, and Fe3+ ions and glucuronic acid on the viscosity, after dry or humid ageing, of two different cellulosic materials, cotton linters and dissolving pulp. The quantity of added metal ions was similar to that found in pulp. In the cotton linters sheets, especially in those containing Mg2+, increased 5-hydroxy-2-methyl furfural (HMF) and 2-furaldehyde (furfural) concentrations were accompanied by decreased viscosity under dry conditions at 180C (pH 5). This indicates that Mg2+ ions can promote the Lewis-acidcatalyzed degradation of cellulose. For cotton linters and dissolving pulp sheets, adding Ca2+ and Mg2+ ions is detrimental when ageing at 180C under dry conditions (pH 5). Adding glucuronic acid increases the viscosity of cotton linters sheets, especially when Ca2+ and Mg2+ ions are present. Due to formation of complexes between the Ca2+ and Mg2+ ions and glucuronic acid, these ions reduce pulp viscosity to a smaller degree.