Surface chemical modification of microfibrillated cellulose: improvement of barrier properties for packaging applications

Heterogeneous acetylation of microfibrillated cellulose (MFC) was carried out to modify its physical properties and at the same time to preserve the morphology of cellulose fibrils. The overall reaction success was assessed by FTIR together with the degree of substitution (DS) defined by titration and the degree of surface substitution (DSS) evaluated by means of XPS. Dynamic contact angle measurements confirmed the hydrophobicity improvement relative to non-modified samples. The increase of contact angle upon reaching a certain reaction time and some decrease following the further acetylation was confirmed. Mechanical properties of MFC films made from chemically modified material were evaluated using tensile strength tests which showed no significant reduction of tensile strength. According to SEM images, dimension analysis and tensile strength data, the acetylation seemed not to affect the morphology of cellulose fibrils.