Utställning: From Trees to Technology – Exploring Forest-Based Materials

Trees play a crucial role in a time of urgent need for a green transition. Forest-based materials have the potential not only to replace fossil products but also to drive innovation across most technological fields.​

At the Wallenberg Wood Science Center (WWSC), researchers explore the amazing building blocks of trees to develop new materials with groundbreaking properties. Transparent wood, the world’s strongest bio-based materials, and membranes for energy storage are just a few examples of how we can create new types of sustainable materials from the forest.​

In this exhibition, you will learn more about the forest as raw material and see examples of research from WWSC at KTH.​

​Explore the journey from trees to technology – and discover how the forest and technology can shape the future!

The exhibition is a collaboration between KTH Library and WWSC.

A world-leading research center on sustainable materials from wood

Wallenberg Wood Science Center is a research center with a focus on new materials from trees, and is since the start in 2009 Sweden’s largest initiative in the field.

WWSC is a joint research center between KTH Royal Institute of Technology, Chalmers University of Technology and Linköping University. The base is a donation from Knut and Alice Wallenberg Foundation (KAW), and the Swedish industry is supporting WWSC via the platform Treesearch.

Sweden is a country rich in forests with 70 % being forest land. The forest industry is of great importance to Sweden, accounting for 9-12 % of Swedish industry's total employment, exports, turnover and value added.

The activities in WWSC are based on that the forest can offer future sustainable biobased alternatives to today’s fossil-based materials, in applications such as packaging and the automotive industry, as well as providing new types of materials. The research goals are set in a long-term perspective, and the research activities span from wood components to novel wood-based applications.

WWSC currently engages ~70 faculty members/researchers, ~50 PhD students in the graduate school WWSC Academy, and ~20 postdocs.

A material composed of 99.99% water – more water than in seawater(!) – is possible with the smallest fiber of the tree, nanocellulose.​

Through the minimal amount of nanocellulose, a network, a hydrogel, is formed that holds the water in place in its given shape.​

Researchers are exploring how to create channels in the trapped water, for example, to conduct biomedical analyses and functionalise these channels. For instance, electrically conductive channels have been created within the extremely water-rich hydrogel.

These are small capsules made from the cellulose of wood, which is first dissolved and then precipitated (known as regenerated cellulose). The capsules are filled with air or another gas during manufacturing, making them very light. And they can be compressed and still return to their original shape!​

The cellulose capsules are used to study the properties and interactions of cellulose but could also be used to make materials lighter, for example, by being mixed into concrete, and to create elastic bio-based materials.

Wood is a natural composite material primarily composed of three main components: cellulose, hemicellulose, and lignin. Together, these building blocks give the tree its unique strength and flexibility.​

In addition to these three main components, wood also contains smaller amounts of extractives, which provide it with specific properties such as scent. ​

Researchers utilise these components and their properties as building blocks for sustainable materials.

Cellulose

Cellulose is the primary building block of wood, making up about 40-50% of its weight, depending on the tree species. Cellulose consists of long chains of glucose molecules that form microfibrils, which in turn constitute the components of the fiber cell wall.​

Ligning

Lignin accounts for about 20-30% of the wood's weight. It is an essential component that acts as a binder between the cellulose fibers, providing wood with its rigidity and resistance to degradation.​

Hemicellulose

Hemicellulose comprises roughly 20-30% of the wood's mass and comprises shorter, branched polymers. Hemicellulose acts as a binding substance between cellulose and lignin.​

There are different processes to extract the pulp (fibers) from wood. Depending on which process is used, the final properties of the products varies.​

The most common pulp is chemical pulp, where the lignin is removed by cooking with chemicals that are then recovered and recycled. In mechanical pulp, on the other hand, the fibres are liberated through mechanical treatment, and all the components of the wood remain. Chemical pulp produces stronger fibers, while the yield is higher for mechanical pulp.​

The pulp can then be further processed, for example, bleached to remove lignin, before being used.

1. Wood chips, softwood (starting material for the pulping)​

2. Wood chips, hardwood (starting material for the pulping)

3. Chemical pulp (kraft pulp, ​e.g., paper, packaging, hygiene paper, other applications of paper e.g., electrical)

a. Chemical softwood pulp​

b. Chemical hardwood pulp​

c. Bleached Kraft hardwood pulp​

4. Fluff pulp (chemical softwood pulp, hygiene products such as diapers)

5. Dissolving pulp (chemical softwood pulp) – chemically pure pulp for textiles (viscose, lyocell, rayon) and cellulose derivatives (e.g., stabilizers in food and cosmetic products)​

6. Mechanical softwood pulp (newsprint paper, hygiene paper, packaging

Biotechnology in the development of sustainable forest-based materials and processes

One route for developing new materials and sustainable processes is biological engineering using microorganisms and enzymes. Here you find three examples of how biotechnology is used in the research!

Residual fibres left over from pulp and paperboard manufacturing accumulate in large volumes, and are hard to recycle due to a high content of water and metals. We are using lab-based cultivation to uncover the microbes that live on these fibres. In future, these microbes and their enzymes will be scaled up for industrial use in waste minimisation and the creation of new fibre-based products.

Cultured cells derived from spruce trees show none of the familiar tree-like morphologies, but they have an intact fibre wall with one key difference – the lignin they produce is secreted into growth media instead of becoming part of the fibre wall. Our work with these cells helped reveal the true structure of lignin, undamaged by industrial processing, and argued for a more lignin-focussed approach to wood refining.

Different views of the crystal structure of a hemicellulose-modifying enzyme found in the wood-rot fungus Humicola insolens. In nature, this fungus secretes such enzymes to gain nutrition from decaying wood material. In industry, enzymes like this one can be used to break apart the fibre wall or to modify the resulting fibres, helping to fine-tune the properties of hemicellulose-based materials.