A group of young researchers from Canada, Finland and Sweden attended the MWP Prize Event in Stockholm in October 2016. The young researchers contributed to the MWP Symposium by presenting their own research in a poster exhibition, see the below abstracts.
- Catalytic pulp bleaching makes industrial breakthrough
Author(s): Ghazaleh Afsahi, Tapani Vuorinen
Corresponding author: Ghazaleh Afsahi
Affiliation: Aalto University
The fully bleached pulps have many applications in production of paper, textiles, nano fibrillated cellulose, etc. However, conventional pulp bleaching processes are mostly based on the use of chlorine dioxide, oxygen and hydrogen peroxide as oxidants. Modern pulp bleaching is mostly based on use of chlorine dioxide, oxygen and hydrogen peroxide as oxidants. In hardwood pulp bleaching a long acidic stage is used to remove xylan-bound hexenuronic acid (HexA) to minimize chemical consumption. Still even the most advanced mills consume ca. 20 kg active chlorine per ton of pulp and large amounts of other chemicals to remove residual HexA and lignin that account for ca. 2 % of pulp weight. A common feature of the most pulp bleaching stages is that the reaction times are long and up to several hours. Recently Aalto University initiated a work on the use of tertiary amines (R3N) as catalysts and HOCl as the oxidant for the pulp bleaching process in the first stage. Just recently, we have experimentally proven if this stage is followed by ozone and peroxide, the whole retention time of pulp bleaching would be decreased from 8 hours to ca. an hour. Moreover, we have shown that the ISO brightness of fully bleached hardwood pulp is in the same order of conventional methods (~88%) with lower chemical dosages (being more environmentally friendly). The study on the tertiary amine catalysis and the short bleaching sequences to obtain fully bleached hardwood kraft pulps could further improve the knowledge of the bleaching process and their usability. Moreover, additional experiments will be carried out on adapting the novel bleaching technology for softwood kraft pulps that are important for the Finnish pulp industry.
Key words: Catalytic pulp bleaching, fully bleached pulp
- Populus FT genes control tree growth and development
Author(s): Domenique André, Ove Nilsson
Corresponding author: Domenique André
Affiliation: Swedish University of Agricultural Sciences
Here we show that FLOWERING LOCUS T (FT) genes control various aspects of tree growth, including height, shoot architecture, biomass distribution, the ability to grow during nutrient scarcity and the length of the growing season. These are important traits determining the fitness of a tree, but also the use one can make of it.
FT has been widely accepted as the dominant component of florigen, a strong promoter of flowering. However, FT-like genes also exist in non flowering plants and it has been proposed that their ancestral function is related to the regulation of annual growth. In poplar, both flowering and growth regulating functions are fulfilled by two FT orthologs with greatly diverged expression patterns. FT1 is expressed during winter in vegetative and reproductive buds. In spring, warm temperatures repress FT1 and long days promote growth through a CONSTANS/FT2 regulon similar to the one in Arabidopsis. Short days in autumn cause FT2 expression and subsequently growth to cease. So far, the individual roles of FT1 and FT2 in bud break and flowering are unknown, neither is the mechanism timing the short-day induced growth cessation well understood.
In this project we aim to identify the individual functions of FT genes. For this purpose we have successfully generated specific knockout mutants of FT1 and FT2, respectively, using the CRISPR-Cas9 technique. These plants are useful tools to investigate the individual roles of FT genes during the annual growth cycle and are now being analysed for differences in e.g. timing of bud set and release of dormancy. Similar experiments are planned for knockout of CEN-like genes, which are antagonists of FT. Furthermore we are investigating how FT controls above mentioned traits, which make it an interesting target for applied but also basic research to understand how growth is regulated in perennial plants and how it can be manipulated to our advantage.
Key words: Populus, phenology, FT, CRISPR
- The action of glucuronoyl esterases on lignin-carbohydrate ester bonds -For an efficient and native wood disassembly
Author(s): Jenny Arnling Bååth, Nicola Giummarella, Sylvia Klaubauf, Martin Lawoko and Lisbeth Olsson
Corresponding author: Jenny Arnling Bååth
Affiliation: Chalmers University of Technology
The Swedish pulp and paper industry is facing challenges with changes in consumer patterns and the increasing competition from fast growing eucalyptus. Together with the need for renewable resources to replace petroleum-based products, the development of new wood-based materials is of great interest to the forest sector. In a materials biorefinery, the components cellulose, hemicellulose and lignin have to be extracted in their native and polymeric form in suitable processes. In these processes, the treatment with enzymes targeting specific linkages, could serve as important steps.
The chemical linkage pattern proposed to connect lignin with hemicellulose, the so-called lignin-carbohydrate complexes (LCCs), is an obstacle for an intact and efficient extraction of wood polymers. It is therefore of interest to find mild methods that would break these lignin-carbohydrate (LC) linkages. Three types of covalent LC bonds have been suggested; benzyl ether-, ester- and phenyl glycosidic linkages.
Cleavage of model substrates mimicking LC ester bonds has successfully been studied with the recently discovered carbohydrate esterase (CE) 15 enzyme family members, Glucuronoyl esterases (GEs). These enzymes are suggested to target the ester bond between aliphatic alcohols on lignin and the glucuronic acid residues present as side chains on wood xylans, but so far, no direct observations of enzymatic cleavage on native LC ester bonds have been demonstrated. In this project we want to elucidate the possible action of GEs on LCC fractions extracted from spruce and birch by combining different analytical techniques, e.g. size exclusion chromatography and 31P NMR.
Our analyses of LCC samples, before and after GE treatment, have now provided the first evidence for cleavage of the LC ester linkages existing in wood and proofs that a GE acts on native LCC substrates. It also adds information on the presence of LC esters in both softwood and hardwood. The discoveries give valuable information on the potential of GEs as a possible ‘green’ treatment step in biorefinery processes.
Key words: Glucuronoyl esterase; Lignin-carbohydrate complexes; 31P NMR; Size exclusion chromatography; Materials biorefinery
- Production of High Strength Technical and Textile Filament-Fibres from cellulose Utilizing Ionic Liquids
Author(s): Shirin Asaadi, Michael Hummel, Herbert Sixta
Corresponding author: Shirin Asaadi
Affiliation: Aalto University
Recently, there has been a growing demand in man-made cellulosic fibres (MMCFs) on the global market. The increasing prosperity of the growing population increases the demand of cellulosic textile fibres, which can no longer be satisfied by the global supply of cotton and the existing man-made cellulosic fibre (MMCF) capacities. In textile industry there is a strong necessity for innovative, green and sustainable technologies in fibre and fabric production, addressing resource efficiency to optimize energy use and material flow to reduce the strain on the environment. Application of cellulose as an eco-friendly raw material in textile manufacturing is a step toward sustainability in textile industry.
Recent studies on the application of ionic liquids (ILs) in cellulose chemistry have attracted a lot of commercial interest, including the production of regenerated and modified cellulose fibres. Ionic liquids have low vapor pressure which prevents the emission of volatile organic compounds (VOCs) and dry-jet wet spun regenerated fibres demonstrate high tensile strength in comparison to commercial fibres (Viscose, Modal, Tencel and tirecord).
Within the last 5 years we have developed a dry-jet wet fibre spinning process at Aalto University, using the ionic liquid 1,5-diazabicy-clo[4.3.0]non-5-enium acetate [DBNH]OAc – called Ioncell-F process.In the first phase of the project, stable spinning conditions have been developed and the regenerated fibres have already shown much better mechanical properties as compared to commercial Lyocell and viscose fibre. The next step is the comprehensive structural analyses of the fibres and cellulose solutions which is a necessary step for the further development in this technology. The aim is to enhance the process to be able to produce regenerated cellulosic fibres with exceptionally high tensile strength and Young’s moduli that would meet or exceed Bocell and tirecord fibres’ mechanical properties.
Key words: cellulose, dry- jet wet spinning, textile fibres, IONCELL-F process
- Switchable ionic liquids as a route to effective nanofibrillation of wood pulp
Author(s): Linn Berglund 1), Ikenna Anugwom 3,4), Mattias Hedenström 3), Yvonne Aitomäki 1), Jyri-Pekka Mikkola 3,4) and Kristiina Oksman 1,2)
Corresponding author: Linn Berglund
Affiliation: 1) Luleå University of Technology, Wood and Bionanocomposite, 2) University of Oulu, Fibre and Particle Engineering, 3) Umeå University, Chemical-Biological Centre, 4) Åbo Akademi University, Johan Gadolin Process Chemistry Centre
Throughout the past few decades the production and modification of nanofibres from forest industry have been given considerable attention in terms of progression towards a more sustainable environment. There are numerous different treatments available to disintegrate pulp fibres into nanofibres with the aim towards a cost efficient production of quality nanofibres. Facilitating the liberation of nanofibres prior to mechanical disintegration is an approach for establishing a viable route for cellulose nanofibres production, with low environmental impact and suitable for industrial production. Switchable Ionic Liquids has shown to be a promising mean of promoting the fibrillation of the fibres down to a nanoscale. Processing of SIL treated materials using ultrafine grinding require significantly less mechanical processing, thus leading to a less energy demanding process, when comparing to the commercial bleached Kraft pulp. Furthermore the nanofibres form networks with high mechanical properties and crystallinity. It is essential to enable separation of the raw material into cellulose nanofibres by investigating environmental friendly options for the processing routes if enforced industrial production of cellulose nanofibres and full potential and environmental benefits of these materials is to be achieved.
Key words: Cellulose nanofibres, Switchable ionic liquid, Grinding, Sustainable processing
- Fire resistance of innovative timber frame assemblies
Author(s): Daniel Brandon, Alar Just
Corresponding author: Daniel Brandon PhD MSc
Affiliation: SP Technical Research Institute of Sweden
A cost effective method to determine properties needed to include fire protective claddings and insulation materials in fire resistance calculations has been developed. As currently available calculation methods only include properties for basic gypsum boards, it is not possible to calculate the fire resistance when using other fire protective cladding or insulation. The use of new advanced products can significantly enhance the fire resistance of timber walls and floors. However, currently this can only be shown by performing numerous full scale fire tests, which is very expensive.
The method gives possibilities for fire resistance calculations using new design models. These new design models are included in the European Technical Guideline for Fire Safety in Timber Buildings and are in the process of being included in the next version of Eurocode 5. For the implementation of new materials into these design models, thermal properties which are effective to predict temperatures throughout the material are determined. The calculation of the thermal properties involves a model-scale fire test and a calibration process, which is automated using a computer algorithm. The resulting properties can be used directly to determine the fire resistance using advanced calculation methods according to Eurocode 5. However, for implementation of the material in the simpler design models of the European Technical Guideline, parameters are determined using a number of thermal simulations. The use of computer algorithms automates the process, which improves the accuracy and cost efficiency of the method. The accuracy of the method was verified by comparisons with full-scale standard fire tests.
Properties of commercial materials and products are implemented in SP-FiT, which is a commercial software used to calculate the fire resistance of timber structures. The new method allows cladding and insulation manufacturers to distinguish their product from competitors’ products, which is creating a more competitive market. Due to this process the number of possibilities to achieve high fire resistances for timber buildings increases and the users of SP-FiT will directly see the advantage of certain products.
Key words: Fire boards, Insulation, Fire resistance, Cladding materials, Thermal properties
- Modification of root system architecture for a sustainable forestry
Author(s): Rubén Casanova-Sáez, Aleš Pěnčík, Afaf Rashed, Ute Voß, Silvana Porco, Nathan Mellor, John R. King, Ilias El-Houari, Rui Pinto, Ondřej Novák, Paul Staswick, Markus Owen, Malcolm J. Bennett and Karin Ljung.
Corresponding author: Rubén Casanova-Sáez
Affiliation: Swedish University of Agricultural Sciences (SLU)
Forests are a crucial resource for the economy of the Nordic countries. Holding about just 1% of the world´s commercial forest area, Sweden provides 10% of the globally consumed forest products. Forestry is, however, vulnerable to climate change effects, such as warming temperatures and either drought or extreme precipitations. Hence, generation of plant varieties with improved fitness under varying environmental conditions is of critical importance for sustainable forestry.
The development of a proper root system is decisive for all plants in order to maximize their fitness, and the plant hormone auxin is known to orchestrate root developmental programs. To get a better understanding of auxin metabolism and root development, we have developed a method for rapid screening of auxin metabolites in plant tissues, based on high-throughput sample purification and liquid chromatography tandem mass spectrometry (LC-MS/MS) profiling combined with multivariate data analysis. We have also generated a collection of Arabidopsis thaliana mutant lines that will serve to identify potential novel regulators of IAA metabolism in plants. In parallel, we recently identified an important mechanism for the regulation of auxin homeostasis in Arabidopsis roots, involving components of its metabolic inactivation pathway (Porco et al., 2016). We are using a combination of CRISPR-Cas9-targeted mutagenesis and modelling approaches (Mellor et al., 2016) to predict the impact of IAA inactivation pathways on auxin homeostasis and root architecture.
As a long-term goal we plan to modulate root architecture in Norway spruce, the most economically and ecologically important tree species in Sweden. However, genetically modified organisms (GMOs) are under strict regulation for ethical and political reasons, and therefore, knowledge generated in the lab is most of the times not transferred to the field. By using the CRISPR-Cas9 technology we aim to generate transgene-free, genetically improved plants, which were recently considered by the Swedish Board of Agriculture not to fall under the European GMO definition, representing a motivating first step for the wide used of genetically edited plants in our forests.
Porco et al., 2016. The dioxygenase-encoding AtDAO1 gene controls IAA oxidation and homeostasis in Arabidopsis. PNAS. In press.
Mellor et al., 2016. Dynamic regulation of DAO1 and GH3 modulates auxin homeostasis. PNAS. In press.
Key words: Auxin, IAA metabolism, IAA homeostasis, root architecture, Arabidopsis, Norway spruce, CRISPR-Cas9, transgene-free
- Fractionation of willow biomass for combined production of fibers, chemicals and energy
Author(s): Jinze Dou, Ulla Holopainen-Mantila, Wenyang Xu, John Ralph and Tapani Vuorinen
Corresponding author: Jinze Dou
Affiliation: Aalto University
Willow bark is a source of interesting polyphenolic heterogeneous compounds and also a potential but little studied feedstock for biorefinery processes. The morphology and chemical composition of inner bark of willow hybrids was analyzed as the first step towards complete willow biomass valorization. The most characteristic features of willow inner bark are the high contents of ash and extractives and the presence of bundles of relatively long and thick-walled fibers. Because of the large tissue volume of thin-walled parenchyma cells, the content of pectin type of polysaccharides is also high in the inner bark. The high extractives content and the fiber quality make willow bark an interesting source of biomass. Recently we discovered that hot water (≥ 70oC) extracted ca. 20% of willow bark in a short time. The main components of the extract – triandrin, picein, catechin, glucose and fructose – were identified by gas chromatography–mass spectroscopy and multidimensional 1H and 13C NMR techniques. Further work will be needed to understand the chemical structure of lignin in inner bark’s sclerenchyma fiber bundles and to develop practical methods for isolation of the fibers.
The completion of this project will open the door for production a variety of high-quality and high-value fibers and chemicals (extractives-derived chemical compounds or intermediates) from willow bark. In combination with efficient use of the debarked willow wood the overall value production will be increased. This will give benefit to forest owners (more productive use of land), materials producers (high quality fibers for special applications, sulfur-free lignin for materials production), sugar/bioethanol producers (novel source of lignocellulosic sugar) and fuel manufactures (bio-oil) as well as energy production companies.
Key words: willow, bark, sclerenchyma fiber, chemical composition, cellulose, hemicellulose, pectin, lignin, extractives, hot water extraction, triandrin, picein, catechin, fructose, glucose
- Cell wall remodelling during ectomycorrhizal symbiosis
Author(s): András Gorzsás 1), Claire Veneault-Fourrey 2), Judith Felten 3)
Corresponding author: Judith Felten
Affiliation: 1) Department of Chemistry, Umeå University, Umeå, Sweden, 2) UMR 1136, INRA-Nancy University, Interactions Arbres/Microorganismes, INRA-Nancy, 54280 Champenoux, France, 3) Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
The majority of temperate and boreal forest trees establish ectomycorrhizal symbioses with soil fungi. Ectomycorrhizae (ECM) increase the tree’s access to nutrients and its growth. Stimulating ECM formation in plantations can lower fertilizer need while insuring high biomass production. To design ECM treatment strategies, ECM formation must be understood; especially its underlying molecular processes. In ECM a mantle of fungal hyphae surrounds the root. Hyphae at the mantle’s periphery acquire soil nutrients. At the mantle/root interface a structure called Hartig Net (HN) forms, which enables the nutrient exchange between the symbionts. HN development requires loosening of lateral walls between adjacent root cells and root invasion by hyphae. Only few genes potentially triggering this cell wall loosening are known, but functional studies assessing their mechanism and necessity are lacking. Uncovering these mechanisms is a first step towards designing strategies to promote tree growth with ECM in plantations and nurseries. I will present my project outline involving a combination of cell wall analytical tools, microscopy, metabolomics and transcriptome analysis on poplar and spruce ECM with different Laccaria bicolor mutant fungi to reveal the fundamental mechanisms for cell wall release that drives HN/ECM formation. Results from Raman-micro-spectroscopy on thin ECM sections will illustrate how state of the art technology for cell wall analysis can be employed to shed light onto crucial processes in ectomycorrhizal formation.
Key words: trees, roots, fungi, symbiosis, ectomycorrhiza, cell wall, Raman micro-spectroscopy
- Oil-in-water Pickering emulsions stabilized by nanocellulosic materials
Author(s): Marie Gestranius 1), Per Stenius 2), Eero Kontturi 3), Johan Sjöblom 2), TeklaTammelin 1)
Corresponding author: Marie Gestranius
Affiliation: 1) VTT Technical Research Centre of Finland Ltd, 2) Norwegian University of Science and Technology, 3) Aalto University, School of Chemical Technology
Emulsions stabilized by biobased materials have gained increasing interest during the last decade due to the demand for efficient and environmentally sustainable emulsifiers, in order to replace conventional synthetic surfactants. Nanocellulosic materials with their naturally amphiphilic character and the ability to form networks have shown great potential in particulate stabilized Pickering emulsions1,2. In this work O/W emulsions stabilized with wood derived cellulose nanofibrils (CNF) and TEMPO oxidized CNF were compared to emulsions stabilized by cellulose nanocrystals (CNC). The chosen nanocellulosic materials differ significantly from each other with respect to particle size and charge; which affect their ability to form networks and interact at the oil-water interphase. The creaming behavior, stability towards dilution, heat and shear as well as droplet sizes were evaluated for emulsions formed with varying oil and nanocellulosic material concentrations. While all emulsions proved highly stable their properties, such as creaming layer volume, clustering of droplets and droplet sizes varied greatly depending on which nanocellulosic material was used. Moreover, TEMPO oxidized cellulose formed two-phase emulsions containing a creaming layer and a phase containing smaller droplets, non-clustering droplets below the creaming layer. Nanocellulosic materials seem to primarily act as stabilizers against coalescence rather than flocculation. These highly refined forest products have shown the potential to act as green and sustainable emulsion stabilizers could be utilized in numerous products such as food, cosmetics, detergents and paints.
- Kalashnikova, I. et al., Langmuir, 2011, 27, 7471–9, doi:10.1021/la200971f
- Gestranius, M. et al., Colloids Surf. A., 2016, in press, http://dx.doi.org/10.1016/j.colsurfa.2016.04.025
Key words: cellulose nanofibril; TEMPO-oxidized cellulose nanofibril; cellulose nanocrystal; emulsion; oil-in-water
- Mild, quantitative and universal fractionation protocol of LCCs. From raw materials to reactivity in technical conditions
Author(s): Nicola Giummarella, Gunnar Henriksson and Martin Lawoko
Corresponding author: Nicola Giummarella
Affiliation: Wallenberg Wood Science Center – KTH
The mission of Wallenberg Wood Science Center is creating new materials from trees for an innovative industrial value creation of forest raw material. Wood, being a complex mixture of biopolymers, challenges the successful extraction and separation of its components in their native form, in high yield and by low energy demand process. To achieve an effective fractionation, it is therefore crucial to gain insight on how these polymers interact with each other in wood.
More specifically, my PhD project is focused on the covalent networks between lignin and hemicelluloses, so called lignin carbohydrate complexes (LCCs) which are believed to play an important role in recalcitrance of biomass fractionation.
We have developed the first universal protocol for the quantitative fractionation of LCCs operating at near-neutral pH and low temperatures, in order to preserve their inherent structures.
Analysis such as 2D HSQC NMR has been applied to decipher the structure of LCCs, complemented by thioacidolysis-GC MS techniques as well as SEC studies. Indisputable proofs of alkyl benzyl ether and phenyl glycosidic bonds between hemicelluloses and lignin were found in the fractions from spruce and birch. Besides, important structural differences in lignin structure, relevant to fundamental knowledge in lignin polymerization and wood-based bio refineries, were unveiled.
Finally, with the aim of understanding the reactivity of LCCs, the described analytical toolbox has been applied in different technical condition such as Kraft and sulfite pulps together with hot water and steam explosion process. Understanding the reactivity of LCCs will hopefully lend important knowledge to wood-based bio-refineries and, in a broader context, make our society less fossil oil dependent by an efficient replacement with wood based polymers products.
Key words: Lignin carbohydrate complexes (LCCs).
- Development of novel photo-induced chemical reaction for nanocellulose film modification
Author(s): Jiaqi Guo, Wenwen Fang, Ilari Filpponen, Pavel Levkin, Orlando J. Rojas
Corresponding author: Pavel Levkin, Orlando Rojas
Affiliation: Karlsruhe Institute of Technology, Aalto University
E-mail: firstname.lastname@example.org, email@example.com
Transparent and flexible nanofibrillated cellulose (NFC) films with good mechanical properties are excellent substrates for analytical, sensor, diagnostic and display applications. However, they are very sensitive to moisture which set limits for their applications. In this work, we developed a novel and facile process to tailor the wettable property of NFC film. Firstly, Transparent reactive porous silicone filaments were indroduced to NFC film surface by polycondensation of trichlorovinylsilane, and then the NFC film bearing reactive vinyl groups can be subsequently functionalized with the photo-induced thiol-ene click reaction. The optimal condition for the growth of silicone nanofilaments on NFC film was investigated with toluene consisting of 125 ppm of water, 625 ppm of trichlorovinylsilane (TCVS) for 24 hours. We created superhydrophobic/hydrophilic NFC film by introducing different thiol compounds with click chemistry. The developed reactive NFC film can be find application for creating pattern for biology and work as screen protector.
Key words: Nanocellulose, Photo-induced thiol-ene reaction, Superhydrophobicity, Slippery lubricant-infused surface, Pattern preparation
- Coagulation of cellulose-ionic liquid solutions for textile fiber production
Author(s): Artur Hedlund, Tobias Köhnke, Hans Theliander
Corresponding author: Artur Hedlund
Affiliation: Swerea IVF & Chalmers University of technology
The Swedish forests constitute an obvious source of raw material for renewable polymeric materials. Close to half its dry mass is cellulose, a non-melting polymer with diverse properties such as the abilities to absorb and transport moisture, retain mechanical cohesion even when wet and be shaped into high tenacity fibers. The drawback of cellulose is its requirement to be dissolved and coagulated in order to be reshaped into any other than its native forms. The coagulation process is very complex and not easily investigated or understood. The complexity of coagulation lies mainly in the separation process of one phase into two phases, whose domains are micro- to nanoscale. The large internal surface areas between these two phases constitute possibilities for high value added niche products, in fields like absorbents and filtration, but in other applications, like textile fibers, they constitute major challenges, as they affect the mechanical properties. In my PhD-project, coagulation of certain ionic liquid-cellulose solutions in water and alcohols has been studied to understand the fundamental aspects of how process parameters translate into material properties, with particular focus on large scale textile fiber production. Aspects that have been studied so far are: the critical concentrations of non-solvent for coagulation, rates of mass-transport and coagulation, the rheological/mechanical properties and the structures of the regenerated materials. Many of these aspects have not been thoroughly studied before and several new methods have been developed in this project to do so. Man-made cellulose fiber is expected to be an important future market for Swedish pulp producers but also increasingly important as a renewable and cheap input to our global retailers of budget home-textiles and garments when cotton becomes increasingly scarce. In addition there are numerous potential applications for regenerated cellulose in hygiene and medicine. This research furthers such developments, by generating a phenomenological understanding of the different sub-processes involved as cellulose solutions transform from liquid to solid.
Key words: Ionic Liquids, Cellulose, Coagulation, Precipitation, Microstructure, Biopolymers, Renewable Materials, Textile Fibers, Diffusion, Rheology, Wet Spinning
- Nanopapers made of lignin-containing cellulose nanofibers isolated from wood pulp
Author(s): Martha Herrera Rodríguez, Ramiro Rojas and Lars Berglund
Corresponding author: Martha Herrera Rodríguez
Affiliation: Royal Institute of Technology (KTH)
The exceptional mechanical properties of cellulose nanofibers (CNF) make them a great option as strength additive for many applications such as films, composites, membranes, and packaging materials. However, they present poor dispersability in non-polar media and aggregation due to their surface hydrophilicity. This property also affects their compatibility with many polymers, such as, polypropylene, polyethylene, or polystyrene and is considered a major drawback for the use of CNF as reinforcement in composites. For improving this property, many different approaches have been used, including the addition or preservation of lignin, which in its native form is more hydrophobic than cellulose.
We have prepared nanopapers from lignin-containing cellulose nanofibers (LCNF) isolated from wood pulp, and dried it using temperature (94 °C) or under pressure at ambient conditions. It was seen that lignin showed liquid flow at temperatures under 100 °C, which promoted a smooth surface and a densified nanopaper. The tensile properties of the nanopapers ranged from 10-11 GPa of modulus, 140-180 MPa of tensile strength and 2-4% of tensile strain. Also, the oxygen barrier properties increased with the densification of the nanopapers.
The use of LCNF is a novel alternative to traditional nanocelluloses and can potentially open the door to new uses and applications compared to CNF. LCNF is an exciting, new field of nanomaterials from biomass, which renovates the interest for preparation methods for nanocelluloses and opens possibilities for exploring new methods of analysis and applications.
Key words: Lignin, cellulose, nanofibers, nanopapers.
- Liquid assisted compounding of cellulose nanocomposites
Author(s): Natalia Herrera-Vargas 1), Aji P. Mathew 2) and Kristiina Oksman 1)
Corresponding author: Natalia Herrera Vargas
Affiliation: 1) Division of Materials Science, Luleå University of Technology, SE-971 87 Luleå, Sweden, 2) Division of Materials and Environmental Chemistry, Stockholm University, SE-10691 Stockholm, Sweden
The interest in develop environmental-friendly materials as well as the need to replace non-renewable materials with bio-based materials have attract the attention of research and industry into the cellulose nanocomposites. Cellulose, which can be obtained from bio-resources or residues, has been used as additive to improve the properties of polymers or biopolymers as poly lactic acid (PLA) when a full bio-based nanocomposite is the target. PLA exhibits high strength, high modulus and film transparency. However, PLA is brittle and has low thermal stability, low impact resistance, low water vapor and gas barrier properties, limiting its potential applications. In order to overcome some of these problems, additives such as plasticizers and nanocellulose have been incorporated into PLA. This study is about the preparation of plasticized polylactic acid/cellulose nanocomposites by melt compounding using liquid feeding of cellulose nanofibers. We have demonstrated that the incorporation of nanocellulose in liquid form during the extrusion process is a good approach to prepare cellulose nanocomposites since the problems associated with the used of dried cellulose are avoided. Plasticized PLA/cellulose nanocomposites with improved elongation at break and toughness than the polymer have been successfully prepared in kilogram scale, resulting in bio-based nanocomposites with potential to be used in packaging applications.
Key words: cellulose nanocomposites, extrusion, compounding, polylactic acid
- Environmental friendly continuous fibers based on cellulose nanofiber
Author(s): Saleh Hooshmand 1), Yvonne Aitomäki 1), Aji P. Mathew 2), Kristiina Oksman 1)
Corresponding author: Saleh Hooshmand
Affiliation: 1) Division of Materials Science, Luleå University of Technology, Luleå, Sweden, 2) Division of materials and environmental chemistry, Stockholm University, Stockholm, Sweden
Fibers play an important role in industrial applications such as in fiber-reinforced composites. Recently, a new type of cellulosic fiber has been produced based solely on native cellulose nanofibers (CNF). We have demonstrated that low cost and environmental friendly fibers can be prepared by dry spinning aqueous suspensions of CNF extracted from a bio-residue, without the use of solvents during the spinning process. The effect of spinning rate and CNF concentration on the mechanical properties of the fibers was investigated. The results showed that higher mechanical properties were achieved by increased spinning rate and decreased concentration of the CNF suspension. This improvement is believed to be due to a more compact structure and an increased orientation of the CNF along to the fiber axis. However, the lowest concentration of that could be spun was still relatively high (≈6.5 wt%) and it is thought that this limits the orientation of the CNF. In the next step, to decrease the CNF concentration to ≈4.3 wt% and subsequently further improve the CNF orientation, a small amount of hydroxyethyl cellulose (HEC) was added to the suspension prior the spinning and the spun fibers were then cold-drawn. The results showed that the addition of the HEC-binder and cold drawing increased the modulus and strength by 76% and 73% to 15 GPa and 260 MPa, respectively. The key advantages of these fibers are their simplicity and eco-friendly process. The results confirmed that dry spinning of CNF has potential for upscaling and for use in structural fiber-reinforced composites, since the properties are comparable with commercial regenerated cellulose fibers e.g. Viscose.
Key words: cellulose nanofibers, hydroxyethyl cellulose, dry-spinning, filament fibers, orientation, mechanical properties
- Requirements and hinders for robotic automation in wood product industries
Author(s): Steffen Landscheidt and Mirka Kans
Corresponding author: Steffen Landscheidt
Affiliation: Linnaeus University
Wood product industries, not only in Sweden, but worldwide lack behind in the development and utilization of flexible and robotic automation in their production processes. In comparison to many other industries, wood product companies stagnate in their technological development of their automated equipment. It is important to understand and identify the requirements, prerequisites and hinders for successful implementation of industrial robots in wood product industries, mainly for industrial timber house building and for furniture and interior design companies.
Wood product companies are not only a cornerstone of the Swedish industry, but they symbolize also a big step into the future since they use and work with a renewable resource that Sweden has quite plenty of: Wood! While other business sectors have progressed into the future and developed new technologies and methods, wood product industries still lack behind by their technology readiness. It is therefore crucial to establish methods, techniques but also technologies for those kinds of companies to stay competitive on a more and more global market.
The purpose of this research is to create an understanding of the importance of automation and to develop a set of tools specifically tailor-made for the needs and demands of wood product industries.
It is investigated if standard automation cells as part of new technological solutions can be developed or if new business models are a better way to advance. By identifying unique, but also common factors for successful automation implementation in comparison to other business sectors, wood product industries can learn and avoid mistakes It is crucial to “break fresh” ground in this area and to break it right from the beginning.
Key words: Flexible manufacturing, robotic automation, wood product industries
- Deep eutectic solvents in nanocellulose production
Author(s): Panpan Li 1), Juho Sirviö 1), Antti Haapala 2) and Henrikki Liimatainen 1)
Corresponding author: Panpan Li
Affiliation: 1) University of Oulu, Fiber and Particle Research Group, Finland, 2) University of Eastern Finland, Faculty of Science and Forestry, Finland
The aim of this study is to investigate how deep eutectic solvent (DES) systems affect the physical and chemical properties of wood-based lignocellulosic fibers and their nanocellulose production. The current experimental results indicate that DESs used as pre-treatment methods lead to enhanced reactivity of cellulose fibers by oxidation and high efficiency in nanocellulose production. In addition, DESs were applied successfully as media to carry out functionalized cellulose reaction.
Both dissolving pulp and bleached birch pulp achieved high yield and increased fiber width after DES treatment. Previous experiment proves non-treated birch pulp has serve difficulty in mechanical nanofibrillation as the clogging of chamber occurred often. However, cellulose nanofibrils with the width ranging from 13.0 to 19.3 nm was successfully fabricated from DES-pretreated fibers, which indicated high efficiency of using DESs in nanocellulose production. Meanwhile, translucent films based on prepared nanocelluloses also showed good mechanical properties and thermal stability. For chemical reaction, periodate-chlorite oxidation was performed to test the dissolving pulp reactivity after DES (Choline chloride – urea) treatment. Compared with original sample, higher amount of acidic groups was obtained on sample surfaces when the sample was pre-treated by DES in the conditions of 120 °C – 4 hours. Furthermore, DES (Lithium chloride – urea) acted as a media for a synthesis of acetyl cellulose, acetylating agents like N-acetylimidazole and acetic anhydride had good performance when the reaction was control at 70 °C for 2 hours.
Prospectively, DESs show high potential as environmentally friendly solvents for further industrial scale manufacture of nanocellulose and functionalized nanocellulose.
Key words: Cellulose nanofibril, deep eutectic solvent, pre-treatment, surface modification, green chemistry.
- Continuous production of wet-spun filaments from cellulose nanofibril hydrogels
Author(s): Meri Lundahl, Ville Klar, Mariko Ago, Gisela Cunha, Orlando Rojas
Corresponding author: Meri Lundahl
Affiliation: Aalto University
Cellulose nanofibrils (CNF) are seen as a high-potential component for future materials combining high performance with renewable origin. However, CNF processing into controlled structures remains challenging. Wet-spinning has been proposed as a method to align cellulose nanofibrils (CNF) and thus achieve materials that fully capitalize on the strength of individual CNF. However, none of the wet-spinning methods introduced so far has attained a continuous, scalable process. Here, we present a method for producing large quantities of cellulose I filament via wet-spinning of CNF. CNF was wet-spun as a core-shell type of composite filament with CNF hydrogel as the core dope and cellulose acetate or guar gum solution as the shell dope. The filament could be spun and collected continuously as well as drawn during the spinning.
The effect of the shell on spinnability was explained by differences in both shear and extensional rheology of the dopes. Drawing was found to improve the mechanical properties of the cellulose acetate -coated filament. Furthermore, the cellulose acetate shell improved the filament stability in water. After the spinning, the cellulose acetate coating could be removed by dissolution in acetone, leading to filaments consisting 100% of CNF. The filament mechanical properties were further improved by changing the shell material to guar gum with better affinity towards cellulose.
In the future, more alternative shell materials can be explored in order to add new features on the filament surface. Also, the shell can be chemically modified to adjust it for different applications. For example, CNF filaments could potentially more effectively reinforce composite materials if covered by a shell that was compatible with the applied matrix.
Key words: Nanocellulose, cellulose I, wet-spinning, core-shell, filament
- Biological Data Visualisation
Author(s): Chanaka Mannapperuma, David Sundell, Nicolos Delhomme, Torgeir Hvidsten, Nathaniel Street
Corresponding author: Chanaka Mannapperuma
Affiliation: Umeå Plant Science Centre
One of the main challenges faced by many biologist is how to benefit from the current data deluge without being overwhelmed by it. As a result, visualisation, the process of transforming data into visual forms, is increasingly important in science as data rapidly expands in both volume and complexity.
Our goal is to improve usability and user interaction of biological tools using human-computer interaction theories and practices. In practical terms this entails identifying specific usability requirements, selecting relevant representations for data as well as actions in the user interface, and offering suitable ways of customising the interaction based on the needs and intuition of individuals end-users. To overcome these challenges requires identification of suitable data representations as well as of activities and tasks used to process the data and an understanding of the variation among individuals in how they approach and perceive tools and data representations.
Over the past years we have been developing a platform (http://plantgenie.org), which is a collection of interoperable web resources for searching, visualising and analysing genomics and transcriptomics data with a specific focus on forest tree species of socioeconomic and scientific interest to Sweden. Currently the platform includes dedicated web portals enabling in-depth exploration of aspen and poplar, Norway spruce, Eucalyptus and Arabidopsis.
Key words: Visualisation, Bioinformatics, NGS Pipelines
- Establishment of Populus species on Swedish forest land
Author(s): Rebecka Mc Carthy, Lars Rytter and Karin Hjelm
Corresponding author: Rebecka Mc Carthy
Affiliation: The Forestry Research Institute of Sweden (Skogforsk)
Populus species and their hybrids are among the most productive tree species in Sweden. Interest in growing them has increased recently due to political goals to enhance the share of renewable energy and to increase the proportion of hardwood species in forests. Several problems resulting in low survival and growth have occurred after planting Populus species on forest land. Therefore, it is of great interest to investigate effects of different soil preparation methods and plant types and to find site specific combinations that secure establishment.
At three sites in southern Sweden, effects on establishment of four soil preparation treatments (control with no soil preparation, patch scarification, mounding and soil inversion) in combination with four plant types (short poplar cuttings, long poplar cuttings, containerized poplar plants and containerized hybrid aspen plants) were studied. For the poplars, different clones of both hybrids and species were used.
Establishment of poplars in terms of survival and growth was influenced by site, soil preparation method, plant type and their interactions. Mounding was the most suitable soil preparation method on all sites, and hybrid aspen showed an overall stable survival and growth. Interactions between site and plant types indicated that poplars were more dependent on site conditions and on suitable sites poplars showed the highest growth. Patch scarification was the least suitable site preparation method and short poplar cuttings appeared to be less suitable for establishing poplars on the type of forest land used in this study.
In addition, the different poplar clones showed varying results in survival dependent on site. Therefore, species, hybrids and clones need to be tested for specific site requirements before implementing these results in practice.
Key words: clone, cutting, growth, plant material, regeneration, short rotation forestry, site properties, soil preparation
- Value-added products from Sphagnum mosses
Author(s): Riina Muilu-Mäkelä, Jenni Tienaho, Anu-Teija Kuovi, Niko Silvan, Robert Franzen, Matti Karp and Tytti Sarjala
Corresponding author: Riina Muilu-Mäkelä
Affiliation: Natural Resources Institute Finland
Mosses, especially the Sphagnum species (sp.), constitute a large part of photosynthesizing biomass in Northern Hemisphere. For instance, one third of total area in Finland is covered by peatlands where Sphagnum sp. is the main component. Many studies indicate that the Sphagnum sp. has potential for value-added products because of its antibacterial or water absorption properties. As a renewable material, use of Sphagnum supports sustainable biological systems.
Traditionally Sphagnum sp. has been used in natural medicine, food preservation or in conservation. Sphagnum species are resistant to microbial decay and their decomposition is very slow. Sphagnum sp. is known to contain commercially important components such as sphagnan, sugars, triterpenoids or phenolics. For instance, Sphagnum sp. contains triterpenoid ursolic acid which is a component of cosmetics. Acidity of sphagnan, a cell wall component of Sphagnum, is part of the antibacterial properties of the mosses. Moreover, Sphagnum sp. is known to harbor antifungal bacteria. The antagonistic potential of Sphagnum sp. and associated bacteria are important reservoir for the biological control of plant pathogens or for the isolation of bioactive compounds. However, molecular level applications are still rarely reported.
We are aiming to develop high-throughput screening methods to evaluate bioactive properties of different sphagnum species. Antibacterial capacity of different extracts (i.e. water, methanol and acetone) have been studied by bacterial biosensor strains (i.e. S. aureus 8325-4/pAT19-luxABCDE-hlaPr-frp and E. coli K-12/pCGLS-1). We use different methods to test (FRAP,ORAC and SCAV) antioxidative efficiency of different extracts and pure compounds. Furthermore, antagonistic potential of Sphagnum sp. and its colonizing microbes against plant and human pathogens will be studied. This study support the renewal of forestry by creating new potential high- value-added products derived from low productive peatland areas. New biotechnological applications will be constructed in collaboration with small and medium sized enterprises.
Key words: Sphagnum sp., high- value-added products, biocontrol, antioxidative efficiency, antibacterial capacity
- Corrosion in biomass fired boilers: diffusion of Cl through oxide scales
Author(s): Mercedes Andrea Olivas Ogaz
Corresponding author: Mercedes Andrea Olivas Ogaz
Affiliation: Chalmers University of Technology
Global warming awareness is increasing day by day. High emissions of CO2 in the atmosphere are primarily causing global warming e.g. use of fossil fuels. However nowadays, in order to reduce CO2 emissions, more alternative energy sources are in use. In Sweden, combustion of biomass is of great importance contributing to the decrease of CO2 emissions. Sweden is increasing the use of natural processes to produce energy, this is not only to reduce CO2 emissions but also used as an economic strategy called bioeconomy, taking advantage of Sweden’s wealth of natural resources. However, there are drawbacks in alternative fuel technologies. Efficiency of biomass combustion compared to fossil fuels is lower which means that in order to produce the same amount of energy produced by fossil fuel, it is necessary to burn greater amount of biomass. Another disadvantage is that biomass and waste are not completely homogenous and contain considerable amounts of alkali and chlorine containing species. The combustion of these fuels produces a corrosive environment for the biomass fired boiler where the process is taking place. This corrosive environment leads to the decrease of life time of some metallic parts of the boiler.
In order to solve this problem, it is important to understand the corrosion mechanism involved. In the boiler, there are a lot of metallic parts where the materials commonly used are low alloyed and stainless steels. At high temperatures, steels tend to oxidize and form different oxide layers which are protective or non-protective depending on their chemical composition. Once steels form the oxide layers chlorine, coming from the flue gas in the boiler, somehow penetrates through the oxide scale. With the understanding of the chlorine-induced corrosion mechanism a big step on biomass fired boiler operation may be done with an intelligent selection of materials that last longer and increase the energy production efficiency.
Key words: Biomass fired boiler, energy production, corrosion, chlorine-induced corrosion, steels, oxide scale
- Water purification with antibacterial cellulose
Author: Anna Ottenhall
Corresponding author: Anna Ottenhall
Affiliation: KTH Royal Institute of Technology
The most important mission straight after an environmental disaster is to provide the inhabitants with safe drinking water. The water treatment systems are often damaged and there is common that the microbial content drastically increase in the surface water e.g. during flooding. The access to safe drinking water is vital since contaminated water often causes diarrheal diseases that have high mortality rates when not treated.
The goal with my project is to investigate if it is possible to create an easy, lightweight and cheap method to sterilize drinking water using antibacterial fibers. The bacteria in the contaminated water are removed with contact-active antibacterial cellulose. The cellulose is functionalized with positively charged polyelectrolytes through physical multilayer adsorption. The modified cellulose fibers gain a positive net charge on the surface and will attract and bind to the negatively charged bacteria from the water. The antibacterial cellulose can remove more than 99.9 % of the bacteria when it is freely dispersed in the water and an even better bacterial removal effect can be obtained if the fibers are processed into water filters.
Most portable alternatives for water treatment today are based on the release of toxic compounds to kill bacteria in the water, which can be harmful both for the environment and the humans drinking the disinfected water. The polyelectrolyte modification on the antibacterial cellulose is on the contrary contact-active i.e. the bacteria are killed upon physical contact with the surface and the polyelectrolytes will not leach into the water. Water filters based on this technology could therefore be a sustainable alternative both for the environment and for the humans drinking the water.
Key words: Water treatment, contact-active material, polyelectrolyte multilayer, cellulose filter
- Efficient enzymatic hydrolysis of plant biomass: a new class of enzymes lytic polysaccharide monooxygenases at play
Author(s): Ausra Peciulyte, Lisbeth Olsson and Katja S. Johansen
Corresponding author: Ausra Peciulyte
Affiliation: Chalmers University of Technology, Gothenburg, Sweden
As a result of the increasing burden on the environment and the scarcity of natural resources, we need to find new ways of supplying a growing population with products for daily life. In a bio-based economy we want to produce bioplastics, biochemicals and biofuels from plant biomass. One of the reasons why plant biomass is interesting is that it could serve as an energy source for microorganisms, which could be used to produce many different products of interest. However, the source of energy in plant biomass is not readily available. We need to use certain enzymes, known collectively as cellulases, which are produced by other microorganisms, such as bacteria and filamentous fungi, to degrade plant biomass into glucose, which can serve as an energy source.
The recent discovery of enzymes termed lytic polysaccharide monooxygenases has led to a significant improvement in the efficiency of enzymatic hydrolysis and thus in the process of the production of biofuels. These enzymes are capable of breaking glycosidic bonds using oxidative mechanism which has not been known until recently. Their mode of action significantly boosts the activity of cellulose hydrolases and glucosidases that act in synergy to decompose cellulose to glucose.
There is a direct connection between fundamental understanding of enzyme mechanism and the development of industrial production of sugar from plant biomass. With the discovery and inclusion of lytic polysaccharide monooxygenases in industrial enzyme cocktail a new unexplored area of importance for biofuel production has arisen. In this project I am specifically focused on addressing how the application of these redox-active enzymes can reach its full potential.
Key words: biofuels, enzymatic hydrolysis, lytic polysaccharide monooxygenases, plant biomass, redox activity
- 3D optical remote sensing of forest
Author: Henrik J. Persson
Corresponding author: Henrik J. Persson
Affiliation: Section of Forest Remote Sensing, Swedish University of Agricultural Sciences
Remote sensing is currently revolutionizing our knowledge about the forests. Satellite- and aerial images have long been used to obtain 2D information about, e.g., tree species and to classify forest/non-forest land. The last couple of years, a third dimension (3D) has been added through techniques such as airborne laser scanning (ALS), photogrammetry and radar systems. ALS and photogrammetry both use acquisitions from aerial platforms, which make them more expensive and impractical to acquire, and the radar resolution is lower, yet sufficient for some applications and not for others. However, technical developments have recently made very high-resolution imagery (30 – 50 cm pixels) available from satellite mounted sensors, which enable frequent, affordable acquisitions of the forest, in three dimensions. This has made it possible to apply the photogrammetric principle (stereogrammetry) on satellite images, without the airborne disadvantages.
In my research, I have performed stereogrammetry with optical high-resolution satellite images, in order to create 3D point clouds, which describe the forest canopy with a resolution better than 1 m – from space! To evaluate the performance and compare it to other techniques, such as ALS, typical forest variables such as basal area-weighted mean tree height, basal area, stem volume and above-ground biomass have been evaluated on field plots with 10 m radius, at two Swedish test sites, located in northern (Krycklan) and southern (Remningstorp) Sweden. Two satellite sensors have been evaluated and when also spectral information (colors) were utilized, the estimation performance exceeded what was achieved with ALS or manual field measurements.
To conclude, stereogrammetry of high-resolution satellite images is a promising technique for forest monitoring purposes and is available also for small forest owners.
Key words: Forest, stereogrammetry, Pléiades, WorldView-2, biomass, height.
- Absolute determination of softwood kraft lignin molar mass using MALDI-TOF and PFG NMR
Author(s): Jerk Rönnols, Karolina Larsson, Anna Jacobs, Fredrik Aldaeus
Corresponding author: Jerk Rönnols
Affiliation: Innventia AB
Lignin isolated from black liquor, a waste product from pulp mills, is an under exploited resource which has high potential in production of carbon fibers, fuels, and high value chemicals. The general molecular properties and in particular the molar mass of lignin are of central importance for industrial applications, since it governs important thermal and mechanical characteristics. The currently prevailing methods for molar mass measurements suffer from different drawbacks, such as need for tedious derivatisation and lacking general models for interpretation.
In this study, a method for absolute determination of kraft lignin weight-average molar mass, based on diffusion constants gained from PFG-NMR calibrated with lignin fractions from size exclusion chromatography, characterized by MALDI-TOF-MS, is presented. This method is comparatively fast, and enables measurement of only the lignin part of the sample.
The method is demonstrated on a group of softwood kraft lignins, for which the results show great resemblance between conventional SEC-measurements and the new method.
The vision of this work is a streamlined production, where rapid NMR-based analysis of the molar mass and chemical structure of lignin enables routes to suitable end products.
Key words: Biorefinery, Black liquor, Diffusion, Lignin, MALDI-TOF, NMR
- Hairy cellulose nanocrystalloids: applied, green nanomaterials
Author(s): Amir Sheikhi and Theo van de Ven
Corresponding author: Theo van de Ven
Affiliation: Department of Chemistry, Centre for Self-Assembled Chemical Structures, Pulp and Paper Research Centre, McGill University
E-mail: firstname.lastname@example.org, email@example.com
Among nanocellulose derivatives, nanocrystalline cellulose (NCC), produced from the strong acid hydrolysis of cellulose fibres, has been known for half a century; however, its application is limited because of poor colloidal stability, even at a moderate ionic strength (e.g., 50 mM of KCl). When cellulose fibres are oxidized using periodate/chlorite, a new class of nanocrystalline cellulose called electrosterically stabilized nanocrystalline cellulose (ENCC) is resulted, which bears protruding dicarboxylated cellulose (DCC) chains sandwiching the crystalline body. In this talk, first, we use electrokinetic-sonic-amplitude (ESA) and acoustic attenuation spectroscopy to assess ENCC zeta-potential and size over wide ranges of pH and ionic strength and compare them to conventional NCC colloidal properties. The results attest to a soft, porous layer of DCC polymers that expands and collapses by changing ionic strength, electrosterically stabilizing ENCC dispersions at ionic strengths up to at least 200 mM of KCl. Then, we show that ENCC can play a significant role as a nanoadsorbent for environmental remediation by scavenging heavy metal ions such as copper. This places ENCC among promising renewable candidates for wastewater treatment. Furthermore, ENCC and DCC are used to mimic the so-called biomineralization of calcium carbonate and customize the formation of least-thermodynamically stable inorganic polymorphs. Also, the potential of these novel hairy nanomaterials for scale inhibition is discussed, and scale-resistant water treatment membranes were developed. We show how the environmental footprint of current antiscalants may be eliminated by using our novel cellulose-based antiscalants. Finally, molecularly-engineered nanocellulose-based hydrogels with finely tuned viscoelastic properties are introduced. The ultimate goal of this project is to promote the forest-based nanotechnology by exploring the potential of hairy NCC in a broad range of disciplines.
Key words: Hairy cellulose nanocrystals, nanocellulose, green nanotechnology, advance materials, colloids
- The impact of wood characteristics on the performance of painted spruce
Author(s): Tinh Sjökvist, Åsa Blom
Corresponding author: Tinh Sjökvist
Affiliation: Linnaeus University, Department of Forestry and Wood Technology
Most research about coatings performance on wood has been focused on the paint system and the coating layer. Few studies, however, can be found regarding the underlying substrate and its specific characteristics. This work concerns how different characteristics of spruce like heartwood, sapwood, high density and low density of spruce affect the performance of a painted panel.
The wood structure varies between different species, but also within the same specie due to for example the climate and forest management. For softwoods, abundance of water and sun often leads to a structure with lower density, larger lumens and thinner cell walls. A less dense structure enhances the liquid permeability in wood. Painted low density spruce has faster uptake of water and higher moisture content compared to high density ones. Heartwood is transformed from sapwood when the tree matures. Differences related to the transformation are firstly the death of living cells but also secondly for example the aspiration of bordered pits, increased level of extractives and depletion of starch. A difference of heartwood and sapwood on the paint performance has been observed, with a higher biological discoloration on painted panels made of sapwood.
The vision is to develop the next generation of painted wood. New knowledge about the impact of the material on a painted product can be used for higher valued end products. For example, durability guaranteed pre-painted panels. One area to increase the use of painted panels can be in multi-storey wooden houses. Production of a special assortment of wood material for painted panels is an opportunity for sawmills to sell their material with a higher value. Also, it could bring the paint industry together with the forest industry to develop the best possible painted wood product.
Key words: Spruce, wood density, heartwood, sapwood, paint, discoloration, moisture content
- Electronic Plants
Author(s): Eleni Stavrinidou, Roger Gabrielsson, Eliot Gomez, Ove Nilsson, Daniel Simon, Magnus Berggren
Corresponding author: Eleni Stavrinidou
Affiliation: Linköping University
Traditionally in forest industry and agriculture protection, improvement and optimization of plants is based on distribution of chemicals in the form of fertilizers and pesticides. More sophisticated methods are based on genetic engineering but these methods are heavily restricted. We propose a revolutionary approach to interface with plants by merging plants with electronics and most recently we have presented for the first time plants with augmented electronic functionality. Using the vascular system and organs of a plant we manufactured organic electronic devices and circuits in vivo, having the internal structure and physiology of the plant as integral part of the device. More specifically we report conducting wires in the xylem vascular tissue of Rosa Floribunda (common Rose) based on conducting polymers. In addition we present xylem circuitry; organic electrochemical transistors, digital circuits and charge storage devices fabricated in the xylem. The device fabrication is based on self organization or in vivo polymerization of the organic electronic materials in the vascular tissue of the plant. In the leaves we show electrochromic pixels, while we demonstrate the possibility of delivering conjugated oligomers from the veins to the apoplast of the leaf, opening pathways for new device concepts. We believe that E- plant technology will bring new scientific tools to plant biologists for fundamental understanding of plant processes and can find application in agriculture, forest industry and energy.
Key words: Electronic plants, organic bioelectronics, conducting polymers
- Antibacterial properties of Scots Pine and Norway Spruce
Author: Tiina Vainio-Kaila
Corresponding author: Tiina Vainio-Kaila
Affiliation: Aalto University, School of Chemical Technology, Department of Forest Products Technology
Wood has always been an important building material in the Nordic countries. Last decades the competition with other materials has become a challenge. Regarding hygienic aspects and the volatile organic compounds (VOC) wood has somewhat disadvantageous reputation. To tackle these challenges, the antibacterial properties of wood have been studied by using both solid wood surfaces and model surfaces of cellulose, hemicellulose, lignin and extractives but also the volatile organic compounds (VOC) emitted from wood. In this interdisciplinary research wood technology is combined with chemistry and microbiology. The results have shown pine heartwood and sapwood and spruce surfaces to have clear antibacterial properties. Further studies have revealed extractives to potentially explain these properties but also lignin to have a minor effect. Even VOCs derived from wood had an antibacterial effect on some bacteria. The results varied depending on the bacterial strains and on the different treatments applied for wood.
The results of these studies bring new aspects to the hygienic properties of wood. Two antibiotic resistant strains (MRSA and VRE) were susceptible to pine extractives, so also some bacterial strains relevant in daycare. These results suggest that wood is a suitable material to be used in hospitals or daycare facilities. The discussion about VOCs is often concentrating on how to decrease the amount of VOCs from building or interior materials. This research presents a different view by showing that the VOCs can actually have a positive effect on the indoor air quality.
The results bring broad possibilities to the use of wood in composites as it is possible to add natural compounds originating from wood. This way the material could be suited for more hygienically challenging end uses.
Key words: Hygienic properties of wood, antibacteriality, wood surfaces
- The effect of cellulose molar mass on the properties of long chain cellulose esters
Author(s): Pia Willberg-Keyriläinen, Jari Vartiainen, Riku Talja, Sari Asikainen, Ali Harlin, Jarmo Ropponen
Corresponding author: Pia Willberg-Keyriläinen
Affiliation: VTT Technical Research Centre of Finland Ltd
Nowadays one of the growing trends is to replace oil-based products with cellulose-based materials. Currently long chain cellulose esters have not been produced commercially due to the high price, since their preparation typically requires a large quantity of chemicals. To reduce the chemical consumption, cellulose reactivity needs to be increased without losing its quality. One way to increase the reactivity of cellulose is to decrease its molar mass in controlled manner. In this study, we have synthesized cellulose esters with different side-chain length (C6-C18) in homogeneous system. The target was to keep the degree of substitution as low as possible while still ensuring the suitability of cellulose esters for solvent casting. Decreasing the molar mass of cellulose by ozone hydrolysis provides cellulose functionalization with less chemical consumption. Based on the results, the molar mass of the starting cellulose has a significant effect on the end product’s degree of substitution and properties. All our molar mass controlled cellulose esters form optically transparent, flexible and heat-sealable films with good water barrier properties and are processable without the addition of external plasticizer. Furthermore films have mechanical properties comparable to some generally used plastics. These good properties suggest that molar mass controlled cellulose esters are potential candidates for various application such as films and composites.
Key words: Long chain cellulose esters, molar mass controlled cellulose, thermal properties, barrier properties, mechanical properties
- Cellulose nanocrystals prepared by mild oxalic acid-catalyzed hydrolysis
Author(s): Wenyang Xu, Henrik Grénman, Jun Liu, Stefan Willför, Anna Sundberg, and Chunlin Xu
Corresponding author: Wenyang Xu
Affiliation: Johan Gadolin Process Chemistry Centre, Åbo Akademi University
The focus of this research study was on developing a sustainable and mild organic acid hydrolysis method to prepare cellulose nanocrystals (CNCs) replacing the use of strong mineral acids, which usually cause problems such as corrosion of equipment, the need of large amount of water, the difficulty of acid recovery, and over-degradation of cellulose.
A one-step method using dilute oxalic acid (0.06-1.11 mol/L) hydrolysis under mild conditions and temperatures of 70 to 100 °C was developed to produce CNCs. A small, catalytic amount of HCl could be added to boost the hydrolysis reaction and also to minimize the chemical cost, since the commercial price of oxalic acid is 2-4 times higher than that of HCl. The reaction kinetics of different preparation parameters were thoroughly investigated for understanding the hydrolysis mechanism in order to develop a well-controlled process of CNC preparation.
A high yield of up to 85 % was achieved by mild oxalic acid hydrolysis of bleached kraft birch pulp. The CNCs from the fore approach have a high thermal stability, i.e. a maximum thermal degradation temperature of 350 °C in comparison to 200 °C when sulfuric acid hydrolysis was used. Importantly, the oxalic acid solutions were readily recovered, and exhibited consistently high performance in several continuous runs of reaction. The hydrolysates contained mostly monomeric sugars, which could be further utilized for chemical or biofuel production. Application of this method to softwood and hardwood sawdust bleached pulps also worked well.
Key words: Cellulose nanocrystals, oxalic acid, reaction kinetics, bleached kraft pulp
- Switchable paper wet strength for applications in agriculture
Author(s): Dong Yang, Robert Pelton
Corresponding author: Robert Pelton
Affiliation: Department of Chemical Engineering, McMaster University
E-mail: firstname.lastname@example.org, email@example.com (Dong Yang)
We propose that agriculture is a huge, untapped market for wood fibre-based materials. We envision 2D (paper-like) or 3D (foam-like) materials providing crop nutrients, releasing pesticides, preventing erosion, or acting as microbiome-promoting plant growth media in greenhouses. Agriculture today is awash with unsustainable plastic films, rock wool and other materials that destined for landfills. By contrast, wood fibres are from renewable sources and after use can be recycled, composted into the soil or burned for fuel. Many of the potential applications require fibre-based materials with sustained strength in the presence of water. This is achievable with conventional wet-strength resins. However, compostability or recyclability characteristics are compromised because the products are too water resistant. The goal of our work is to develop novel wet strength agents for cellulose surfaces whose adhesive characteristics can be switched off at the end of the growing season.
Our initial attempts were based on microgel adhesives with labile disulfide linkages. Cellulose wet adhesion provided by disulfide microgels can be degraded in response to mild reducing agents. A mechanistic model was constructed to simulate and predict the “switchable” properties of redox-responsive microgel adhesives. Microgel size was shown to be not important, whereas crosslinking density of microgels had a great influence on cellulose-cellulose adhesion. The ratio of stable and labile linkages in microgels was varied to give intermediate responses to reduction. In addition, we have shown that a traditional wet strength resin poly(amideamine epichlorohydrin) (PAE) was compatible with redox-responsive microgels. Switchable microgels coated with PAE gave strong wet adhesion that could be reversed with a mild reducing agent.
Key words: Agricultural paper, Paper chemicals, Cellulose wet adhesives, Redox responsive microgels
- A bottom-up route to a chemically end-to-end assembly of nanocellulose fibers
Author(s): Han Yang, Theo van de Ven
Corresponding author: Theo van de Ven
Affiliation: McGill University
In this work, we take advantage of the rod-like structure of electrosterically stabilized nanocrystalline cellulose (ENCC, with a width of about 7 nm and a length of about 130 nm), which has dicarboxylated cellulose (DCC) chains protruding from both ends, providing electrosterical stability for ENCC particles, to chemically end-to-end assemble these particles into nanocellulose fibers. ENCC with shorter DCC chains can be obtained by a mild hydrolysis of ENCC with HCl, and subsequently the hydrolyzed ENCC (HENCC, with a width of about 6 nm and a length of about 120 nm) is suitable to be assembled into high aspect ratio nanofibers by chemically cross-linking HENCC from one end to another. Two sets of HENCC were prepared by carbodiimide-mediated formation of an alkyne and an azide derivative, respectively. Cross-linking these two sets of HENCC was performed by a click reaction. HENCCs were also end-to-end cross-linked by a bioconjugation reaction, with a diamine. From atomic force microscopy (AFM) images, about ten HENCC nanoparticles were cross-linked and formed high aspect ratio nanofibers with a width of about 6 nm and a length of more than 1 μm.
Key words: nanocrystalline cellulose, end-to-end assembly, cross-linking, click reaction
- Spherical nanocomposite particles prepared from mixed cellulose-chitosan solutions
Author(s): Jiayi Yang, Björn Lindman, Håkan Edlund, Magnus Norgren
Corresponding author: Jiayi Yang
Affiliation: Mid Sweden University
Novel cellulose-chitosan nanocomposite particles with spherical shape were successfully prepared via mixing of aqueous biopolymer solutions in three different ways. Macroparticles with diameters in the millimeter range were produced by dripping cellulose dissolved in cold LiOH/urea into acidic chitosan solutions, inducing instant co-regeneration of the biopolymers. Two types of microspheres, chemically crosslinked and non-crosslinked, were prepared by first mixing cellulose and chitosan solutions obtained from freeze thawing in LiOH/KOH/urea. Thereafter epichlorohydrin was applied as crosslinking agent for one of the samples, followed by water-in-oil (W/O) emulsification, heat induced sol-gel transition, solvent exchange, washing and freeze-drying. Characterization by X-ray photoelectron spectroscopy (XPS), total elemental analysis, and Fourier transform infrared spectroscopy (FT-IR) confirmed the prepared particles as being true cellulose-chitosan nanocomposites with different distribution of chitosan from the surface to the core of the particles depending on the preparation method. Field emission scanning electron microscopy (FE-SEM) and laser diffraction was performed to study the morphology and size distribution of the prepared particles. The morphology was found to vary due to different preparation routes, revealing a core shell structure for macroparticles prepared by dripping, and homogenous nanoporous structure for the microspheres. The non-crosslinked microparticles exhibited a somewhat denser structure than the crosslinked ones, which indicated that crosslinking induced a lower degree of freedom during packing of the chains before and under regeneration. From the obtained volume-weighted size distributions it was found that the crosslinked microspheres had the highest median diameter. The results demonstrate that not only the mixing ratio and distribution of the two biopolymers, but also the morphology and nanocomposite particle diameters are tunable by choosing between the different routes of preparation.
Key words: cellulose, chitosan, nanocomposite, microspheres, regeneration
- Cellulose fiber based fungal and water resistant insulation materials
Author(s): Chao Zheng, Dongfang Li, Anna Ottenhall and Monica Ek
Corresponding author: Monica Ek
Affiliation: Department of Fiber and Polymer Technology, KTH Royal Institute of Technology
E-mail: Chao Zheng: firstname.lastname@example.org, Monica Ek: email@example.com
Thermal insulation made from natural fibrous materials, such as cellulose fibers, have advantages over the others, from a sustainability point of view. In this study, cellulose fiber based insulation foams were prepared from bleached Chemithermomechanical pulp, which showed promising thermal insulation property and fungal resistance. Hydrophobic extractives were isolated from birch (Betula verrucosa) outer bark and used to improve the water resistance of the foams. The foams were impregnated in the solutions of extractives and then dried. Scanning electron microscopy was utilized to evaluate the surface morphology of the foams and the distribution of deposited particles of the extractives. The modified foams showed improved water resistance as they did not deform after immersion in water for 7 days, whereas the unmodified foam did. Moreover, compared to the unmodified foam, the modified foams absorbed 50% less moisture within 24 h. Besides, the modification had no negative effects on the thermal insulation property, fungal resistance, and compressive strength of the foams. This study demonstrated an easy approach to prepare functional insulation materials entirely based on renewable resources, which is in agreement with the biorefinery concept.
Key words: biorefinery, birch bark, cellulose, insulation, fungal resistance, water resistance