Browsing by Author "Maloney, Thad, Prof., Aalto University, Department of Forest Products Technology, Finland"

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The manufacturing potential of micro and nanofibrillated cellulose composite papers
(2016) Rantanen, Juuso
School of Chemical Technology | Doctoral dissertation (article-based)
This study presents a novel approach for producing composite papers that have fundamentally different properties to the traditional products in the paper industry. The main focus of this work was to evaluate the use of micro and nanofibrillated celluloses (MNFCs) as a component in paper in conjunction with traditional fillers and pulp fibers. The main hypothesis of this thesis work was that it is possible to form and subsequently dewater furnishes that contain considerable amounts of MNFC. Moreover, the properties of these new MNFC composite papers were expected to differ from traditional paper characteristics. The properties of MNFC composite papers were studied with different compositions of pulp fibers, MNFC, and filler. It was concluded that the optical properties of the composite papers were excellent and that the use of fillers together with MNFC results in a unique micro and nanoporous network structure of the paper. The in-situ precipitation of calcium carbonate directly on the MNFC fibrils was also shown to be a promising method for adjusting the water uptake of the MNFC and the resulting paper properties. The cost structure of the MNFC composite proved to be very attractive due to a reduction in the level of more expensive fibers required. The shear thinning behavior of the MNFC composite suspension was shown to enable 5-10 % solids content in forming, and subsequent wire dewatering to 33 % solids content. In addition, this work demonstrated that a wet pressing process can be used for the efficient dewatering of the MNFC composite furnishes if long enough press pulses are used. Under some conditions the dewatering was found to be better than with kraft pulp fibers alone. This thesis work clearly establishes that a wide range of high value MNFC based products can be formed using a feasible, efficient and economical process – a critically important step towards the next generation of products and processes based on forest resources.