Bleached and unbleached MFC nanobarriers - properties and hydrophobization with hexamethyldisilazane

Updated: 2012-12-17 | Print

Gary Chinga-Carrascoa, Nina Kuznetsovab, Milyausha Garaevab, Ingebjørg Leirseta, Guzaliia Galiullinab, Anatoly Kostochkob, Kristin Syveruda

a Paper and Fibre Research Institute (PFI), Høgskoleringen 6b, NO-7491 Trondheim, Norway.

b Kazan National Research Technological University, Karl Marks 68, 420015, Kazan, Russia

This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenization without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. The HMDS-modified films made of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m-2 day-1 atm-1, which is a good property for some packaging applications.