2019

Willberg-Keyriläinen, Pia; Ropponen, Jarmo; Lahtinen, Manu; Pere, Jaakko

Reactivity is an important parameter when considering the chemical modification or dissolution of cellulose. Different pretreatment methods affect cellulose reactivity by decreasing its degree of polymerization (DP) and crystallinity. In this study, the molar mass of cellulose was decreased via enzymatic pretreatment. Three commercial endoglucanase-rich products were tested. The target was to reduce the viscosity of the pulp to below 200 mL/g and, thus, increase the reactivity of the cellulose. For comparison, cellulose was also pretreated with ozone, and the effects of each pretreatment method on crystallinity and monosaccharide composition of the resulting pulps were investigated. Both enzymatically treated and ozone-treated pulps were esterified using homogeneous and heterogeneous methods, and the degrees of substitution for these treated pulps were much higher than the esters when the untreated pulp was used. Cellulose esters from the pretreated pulps formed films with good mechanical properties by solvent casting.