Department of Bioproducts and Biosystems

Wood Material Science

The wood material science group, led by Professor Lauri Rautkari, focuses on a variety of subjects ranging from developing thermal modification processes and improving the properties of wooden construction materials to microbiology and chemistry of wood and wood components. The task for this group is to develop new sustainable, environmentally friendly and diverse wood products with enhanced properties.

Our research areas:

  1. Wood-water interactions

  2. Chemical imaging of biomaterials

  3. Wood modification

  4. Wood products and properties

Microscopic image of wood piths
SEM-image of wood piths (Daniela Altgen)

Wood-water interactions

Wood contains polar functional groups that attract water molecules from the surroundings. Absorbed water influences the performance of wood significantly (strength and stiffness, swelling, risk for deterioration by decay fungi). A better understanding of wood-water interactions will thus help in improving the performance of wood in the built environment.  

Our group investigates the principles of how wood interacts with water molecules under different climatic conditions. We have developed several methods to study wood-water interactions in automated sorption balances. Besides traditional sorption isotherm measurements, we also specialize in quantifying accessible sorption sites in automated sorption balances using the deuterium exchange approach. We are also analyzing the link between moisture content changes and structural changes of the wood cell walls at the micro- and nanoscale using state-of-the art characterization tools such as confocal Raman microspectroscopy, or x-ray scattering techniques.  

Related publications (examples)

Quantitative prediction of moisture content distribution in acetylated wood using near-infrared hyperspectral imaging

Awais M., Altgen M., Mäkelä M., Belt T., Rautkari L. 2022 Journal of Materials Science 57:3416–3429

Water-accessibility of interfibrillar spaces in spruce wood cell walls

Penttilä P., Zitting A., Lourençon T., Altgen M., Schweins R., Rautkari L. 2021 Cellulose 28: 11231–11245

Humidity-dependence of the hydroxyl accessibility in Norway spruce wood.

Altgen M., Rautkari L. 2021 Cellulose 28:45-58

Effect of drying on the hydroxyl accessibility and sorption properties of pressurized hot water extracted wood

Kyyrö S., Altgen M., Belt T., Rautkari L. 2021 Wood Science and Technology, 55: 1203–1220

Moisture-related changes in the nanostructure of woods studied with X-ray and neutron scattering

Penttilä P. A., Altgen M., Carl N., van der Linden P., Morfin I., Österberg M., Schweins R., Rautkari L. 2020 Cellulose 27:71-87

Dynamic vapour sorption protocols for the quantification of accessible hydroxyl groups in wood.

Uimonen T., Hautamäki S., Altgen M., Kymäläinen M., Rautkari L. Holzforschung 74(4):412-419
Close-up of RAMAN imaging device, wood sample image at the background

Chemical imaging of biomaterials

As a natural product, wood and other cellulosic biomaterials often suffer from chemical heterogeneity in spatial dimensions. Such heterogeneity may occur naturally, for example the variation in heartwood extractives, or can be the result of wood treatments and processing. A particular challenge of wood is its hierarchical, cellular structure, which requires us to analyze chemical heterogeneity at the macroscopic scale (several millimeters or more) and at the microscopic or cellular level (several micrometers or less).  

In our group, we are analyzing chemical heterogeneity at different spatial dimensions by combining different chemical imaging tools, including confocal laser scanning microscopy, confocal Raman mapping and hyperspectral near infrared imaging. We are also focusing on applying chemometrics based on multivariate data analysis, which utilize the entire spectral range measured to find chemical differences in samples. We have used these chemical imaging methods in several research topics, ranging from the distribution of heartwood extractives in Scots pine wood to the process-related variation in modification degree in acetylated or impregnation-treated woods.  

Small different color wood samples placed on sample holders

Wood modification

Our native wood species typically do not have a sufficient durability in exterior applications and there are growing environmental concerns for the use of biocides for wood protection. An alternative approach is the modification of our native wood species with thermal, chemical, or other methods. The modified wood remains non-toxic during its service life and beyond and shows improved dimensional stability and decay resistance.  

Our group investigates different wood modification treatments, ranging from thermal modification methods and hygrothermal densification to chemical and impregnation-based modification methods or surface treatments using wood charring and biofilm coatings. We investigate the fundamental modes of action in modified woods and develop new strategies to modify our native wood species efficiently. Our laboratories offer a range of analytical tools to study anatomical and chemical changes of the cell wall as well as the resulting wood properties.  

Birch veneer stripes in a plastic cup

Wood products and processes

Wood from sustainably managed forests is an excellent building material thanks to its high strength-to-weight ratio and its ability to store carbon over long periods. There is diversity of wooden products with different properties and applications, which range from solid wood products (i.e. cross-laminated timber and glued laminated timber) to veneer-based products (i.e. plywood and laminated veneer lumber) to particle- and fiber-based products (i.e. particle and fiber boards). Our group investigates the properties and behavior of raw wood materials, such as the distribution of heartwood extractives and its impact on biological durability, anti-bacterial effects of wood surfaces or the humidity-dependence of mechanical properties. We are also cooperating with industrial partners to optimize the manufacturing conditions, or to develop new processing concepts for a more efficient use of wood in the built environment. We have a strong expertise in the evaluating the wood bondability with different adhesive systems or the design of wood products for novel applications.  

Wood science teaching

We offer teaching related to wood material science, wood products and processes as well as life cycle analysis of wood products. We are continuously developing our teaching and recently focusing on high-quality online learning. Online learning enables us to provide teaching to a wider audience, including students from different fields in Aalto, students from other universities, as well as, life-wide-learners. 

Find out more about our courses here.

To support learning we keep on developing new learning materials and videos, such as presented below. Even more videos can be found from this Youtube-channel:

Aalto University - Wood Science

Demonstrating thermal modification of wood - photo: Olli Häkämies

The 4-year Academy of Finland funded project HotWood investigates what happens to the ultrastructure of wood, when it is modified in superheated water at high pressure. Find out more about this and other projects at metsä.fi!

CHEM_Prof Lauri Rautkari

Join us!

We are continuously looking for talented researchers (Aalto students, MSc thesis workers, doctoral students and postdocs).

For further information, contact Prof. Lauri Rautkari ([email protected])

Research group members:

Photo of research group members outdoors
Group photo by Kristina Tsvetkova (2022)

Related content:

New Academy Projects to be launched in September

New Academy Projects funded by the Academy of Finland involve expertise from all six Aalto schools

Organ type of image with white "veins" and small bacteria dots in red background, original image by Valeria Azovskaya

Nearly 20 million euros for research

The Academy of Finland funding brings nine new posts as Academy Research Fellow, 15 new Postdoctoral Researchers and 24 new Academy Projects to Aalto University.

Four engineering scientists in pink t-shirts in front of an an engine

Anything but an ordinary greenhouse

A wood-structured windowless greenhouse consumes only half as much energy as a traditional glass greenhouse. In addition to producing food, Pasi Herranen’s invention could generate electricity and excess heat in the future.

Kuvassa Pasi Herranen, Orvokki Ihalainen ja Panu Miettinen

Wood Wonders exhibition showcases climate-friendly building concepts

If all the buildings constructed in Finland each year were made of wood, the amount of wood needed for their construction would grow back in ten hours.

Wood Wonders exhibition at Helsinki airport. Photo: Anne Kinnunen

New minor: Aalto Wood

For students in any field interested in wood!

Cross-cut wood disk on a wooden table

Wood science teaching

Wood science is taught by the Department of Bioproducts and Bioprocesses.

Cross-cut wood trunk in the forest

Latest publications:

Hyperspectral Imaging Predicts the Moisture Content Distribution in Acetylated Wood

Muhammad Awais, Michael Altgen, Mikko Mäkelä, Tiina Belt, Lauri Rautkari 2022

Quantitative prediction of moisture content distribution in acetylated wood using near-infrared hyperspectral imaging

Muhammad Awais, Michael Altgen, Mikko Mäkelä, Tiina Belt, Lauri Rautkari 2022 Journal of Materials Science

Size-dependent filling effect of crystalline celluloses in structural engineering of composite oleogels

Mamata Bhattarai, Paavo Penttilä, Luisa Barba, Braulio Macias-Rodriguez, Sami Hietala, Kirsi S. Mikkonen, Fabio Valoppi 2022 LWT

Review of the use of solid wood as an external cladding material in the built environment

Callum Hill, Maija Kymäläinen, Lauri Rautkari 2022 Journal of Materials Science

Artificial Weathering of Contact-Charred Wood—The Effect of Modification Duration, Wood Species and Material Density

Maija Kymäläinen, Tinh Sjökvist, Jakub Dömény, Lauri Rautkari 2022 Materials

Effect of Moisture on Polymer Deconstruction in HCl Gas Hydrolysis of Wood

Tainise Lourençon, Michael Altgen, Timo Pääkkönen, Valentina Guccini, Paavo Penttilä, Eero Kontturi, Lauri Rautkari 2022 ACS Omega

Nanoscale Mechanism of Moisture-Induced Swelling in Wood Microfibril Bundles

Antti Paajanen, Aleksi Zitting, Lauri Rautkari, Jukka A. Ketoja, Paavo A. Penttilä 2022 Nano Letters

Base-catalysed depolymerization of lignins in supercritical water: Influence of lignin nature and valorisation of pulping and biorefinery by-products

Eduardo Pérez, Nerea Abad-Fernández, Tainise Lourençon, Mikhail Balakshin, Herbert Sixta, María José Cocero 2022 Biomass and Bioenergy

Review of Wood Modification and Wood Functionalization Technologies

Samuel L. Zelinka, Michael Altgen, Lukas Emmerich, Nathanael Guigo, Tobias Keplinger, Maija Kymäläinen, Emil E. Thybring, Lisbeth G. Thygesen 2022 Forests
More information on our research in the Research database.
Research database
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