Search

Foam forming of cellulose fibre materials is based on an interaction between fibres and bubbles, which can take several material properties to new levels. To control the formed structure, the mechanisms of this interaction have been systematically investigated. This started with captive bubble studies where we analysed the interaction of a single bubble with various smooth cellulose and silica model surfaces. The bubbles adhered only to hydrophobic surfaces, and this attraction was sensitive to the surface tension. From this simplest case, the studied system gradually became more complex. We found that a bubble adheres weakly also to a submerged cellulose nanofibre (CNF) film, which could be explained by nanoscale surface roughness capturing nanobubbles. The interaction with real fibres was studied by pressing a single bubble against a fibre bed in water and sodium dodecyl sulphate (SDS) solution. Fibre type and surface tension had all apparent effects on the attachment. In the case of natural fibres, the presence of hydrophobic lignin clearly increased the fibre attachment on a bubble, while added SDS decreased the attachment with all fibre types. These findings agreed with the mechanisms found earlier using the model surfaces. Finally, when forming thick nonwoven materials using hydrophilic and hydrophobic viscose fibres, differences in fibre network structure and strength properties depended on the fibre hydrophobicity and surfactant type, as suggested by the results obtained in simpler systems.

FinnCERES is a Competence Centre formed between Aalto University and VTT Technical Research Centre of Finland (www.finnceres.fi). This combination yields a unique combo of highly ranked fundamental and applied research in the area of forest-sourced materials. In addition, the strength of the alliance derives from its state-of-the-art research infrastructure including pilot capabilities, and global research and industrial networks. We aim at holistic material sustainability considering today’s demands on the smart use of biomass. In the current materials design, the specific inherent properties and added value of lignocellulosics are emphasised even more than merely their renewable origin or biodegradability. We consider plants as our future material bank since cell wall components, structure and functions are an endless source for inspiration for the materials science and engineering. The aim of the research programme is to bridge the gap between fundamental and applied research as well as to provide a fast track for scientific findings towards real innovations and industrial implementation. This presentation highlights the latest scientific advances from the research programme which is divided into five major research themes: 1) Fundamentals: Interactions and advanced characterisation, 2) Future biorefineries, 3) Clean air and water, 4) Lignocellulosics beyond plastics, and 5) Electronics, optics, and energy applications. In addition, the recent progress and actions within the FinnCERES Ecosystem including the Boreal Alliance will be communicated.

Funding The work leading to this article has been made in the ValBio-3D project funded by the Academy of Finland via the ERANet-LAC program, and partially in the FireCellCoat project funded by the Ministry of Agriculture and Forestry of Finland via the BIOECONOMY IN THE NORTH program. The work is a part of the Academy of Finland’s Flagship Programme under Projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). KSK acknowledges Academy of Finland project 310943 for funding. Oil-in-water emulsions stabilized using cellulose nanofibrils (CNF) form extremely stable and high-volume creaming layers which do not coalesce over extended periods of time. The stability is a result of the synergistic action of Pickering stabilization and the formation of a CNF percolation network in the continuous phase. The use of methyl cellulose (MC) as a co-emulsifier together with CNF further increases the viscosity of the system and is known to affect the droplet size distribution of the formed emulsion. Here, we utilize these highly stable creaming layer systems for in situ polymerization of styrene with the aim to prepare an emulsion-based dope for additive manufacturing. We show that the approach exploiting the creaming layer enables the effortless water removal yielding a paste-like material consisting of polystyrene beads decorated with CNF and MC. Further, we report comprehensive characterization that reveals the properties and the performance of the creaming layer. Solid-state NMR measurementsconfirmed the successful polymerization taking place inside the nanocellulosic network, and size exclusion chromatography revealed average molecular weight (Mw) of polystyrene as approximately 700,000 Da. Moreover, the amount of the leftover monomer was found to be less than 1% as detected by gas chromatography. The dry solids content of the paste was ∼20% which is a significant increase compared to the solids content of the original CNF dispersion (1.7 wt%). The shrinkage of the CNF, MC and polystyrene structures upon drying—an often-faced challenge—was found to be acceptable for this composite containing highly hygroscopic biobased materials. At best, the two dimensional shrinkage was no more than ca. 20% which is significantly lower than the shrinkage of pure CNF being as high as 50%. The paste, which is a composite of biobased materials and a synthetic polymer, was demonstrated in direct-ink-writing to print small objects. With further optimization of the formulation, we find the emulsion templating approach as a promising route to prepare composite materials.

Executive summaryResource efficiency, investments and focus on added value• Since launch of the first Finnish Bioeconomy strategy in 2014 the economic output of the bioeconomy has increased particularly in the forest and constructionsectors resulting from larger production volumes. In the future, however, moreemphasis should be put on value-adding investments and production.• Initially, the economic output and social welfare created by bioeconomy were emphasized. Today, also the concern about the changing climate and loss of biodiversity challenge bioeconomy, its raw material sourcing and product life cycles.• Biomass is an abundant yet constrained resource. Investing in new, resourceefficient processes holds significant potential in increasing both the overall production and the value of the existing resource use.Insights and snapshots of future products• A larger share of the forest based value chain could be in Finland when customertailored solutions are designed and produced prior to transportation. Packagingsolutions, textiles, wood construction and lignin based value added productscould be emphasised as examples.• Realising the unutilised potential in conventional agriculture to increase production efficiency and at the same time radically cut down the environmental impactand maintain safety brings significant competitive advantage. The potential canbe fully capitalised through the more efficient use of data and advanced digitalsystems in production planning and monitoring.• Emerging food production technologies such as vertical farming, aquaculturebased on water circulation, and cellular agriculture are rapidly developing. In thefuture, they can offer alternative solutions for food production when harnessedbased on solar and other renewable energy production.• Versatility in the energy system is key to increasing resilience in the energy transition currently taking place. The constrained biomass resources available for theenergy sector should be directed to the most valuable uses from the systemicperspective with special focus to industrial uses, and other hard to decarbonisesectors such as long-haul transport including marine and aviation transportation.Also the efficiency of existing biomass-based energy generation can be improvedsignificantly by reducing losses throughout the supply chain.Future services and knowhow• Nature based services are essential part of bioeconomy and offer increasingsources of health and welfare also for urban populations. Nature experiences andnew types of services (soft adventure, packaged products, guidance, products forurban users etc.) form basis for growing tourism and business.• Technology industries offering technology, services and machinery for the bioeconomy is a vital and increasing part of the Finnish bioeconomy and its export.Long traditions and investments in high level education and innovation cultureform foundation for successfully renewing technology ecosystems.