The by-product lignin can play a key role in new sustainable materials

In her research project, Matilda Johansson, now holder of a doctorate in Polymer Technology, has investigated how lignin can be chemically modified and used in fibre-reinforced biocomposites. The goal was to create materials that can not only replace oil-based products but also reduce the weight of structures without compromising mechanical properties.

The project has revolved around four key issues: How can the compatibility of lignin with other substances be improved? How can the modification process be made more efficient and environmentally friendly? How can the mechanical and thermal properties of the material be improved? And how can a fibre be incorporated to further strengthen the material?

“There are many unexplored possibilities for lignin. By chemically modifying lignin, it is possible to create a material that has great potential to replace oil-based materials,” said Matilda Johansson.

Simple and effective method 

The method involves extracting lignin from forest and agricultural waste and chemically modifying it using acetic anhydride and microwaves. This allows the lignin to bind with other polymers, such as PLA (Polylactic Acid). Then, methods such as extrusion, 3D printing and compression moulding are used to create a composite reinforced with regenerated cellulose fibres.

Environmental benefits and resource efficiency

“The project contributes to minimising the use of traditional plastics, i.e. oil-based materials. The material consists of natural components and no harmful chemicals are used during production. More and more industries are switching to bio-based alternatives and this material could be an option to reduce climate impact. The fact that it also consists of a material that is considered to be a byproduct from another industry, i.e. of low value, makes the whole process more resource efficient,” explained Matilda Johansson.

The project is an important contribution to research on sustainable materials. This demonstrates the importance of developing environmentally friendly alternatives to today’s materials.

With sustainability in focus 

“Today’s high consumption means that there is an incredible amount of material, yet a very small proportion is recycled, resulting in accumulations of material that contribute to a lot of destruction in nature. If it is possible to choose a material that has had less impact on nature when it is produced as well as less impact on nature when it is used, that’s a win-win,” said Matilda Johansson.

The project supports the UN’s Sustainable Development Goals, primarily Goal 9, Industry, Innovation and Infrastructure, and Goal 12, Responsible Consumption and Production.

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Matilda Johansson defended her doctoral thesis on 25 April at the University of Borås.

Principal supervisor: Professor Mikael Skrifvars

Assistant supervisor: Professor Nawar Kadi

External examiner: Dr. Bruno Medronho, University of Algarve, Portugal

Read the thesis: Valorising lignin: A pathway to sustainable and high-performance biocomposites

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