Plastic pollution, micro- and nanoplastics are increasingly entering our environment where they pose significant problems to the ecosystems. VTT excels in developing wood-based materials. These show great promise in addressing plastic pollution in the environment, as wood is naturally biodegradable.
However, this unique feature also limits the use of wood-based materials in applications that require resistance to natural conditions. These include end uses like agricultural mulch films, geotextiles, insulators, insulation and barrier films for construction, marine and agricultural nets and soil contact timber.
Typically, nature-resistant cellulosic materials are produced using toxic preservatives that permanently treat the materials or slowly leach out over time. VTT innovates safe and sustainable methods to customise the biodegradability of wood-based materials, making them suitable for more challenging environments.
“While our know-how to tailor materials’ biodegradability is still in the relatively early stages, we are eager to connect and collaborate with companies that need solutions to reduce the biodegradation rate of their cellulosic materials,” says Senior Scientist Ilona Leppänen from VTT.
The tailored biodegradability of cellulose enables the customization of degradation time to suit specific applications
VTT has put research efforts on demonstrating that it is possible to modify cellulose so that the biodegradation time can be controlled without toxicity challenges. Applying chemical treatments to cellulose is one method to increase the durability of wood-based materials against outdoor conditions, allowing for customised biodegradability. We have tested a variety of different lignocellulosic materials with varying degrees of modification.[1]
“It was demonstrated that degradability declines exponentially as modification increases. The degradability was reduced significantly as the degree of modification approaches one (with three being the maximum). Therefore, controlling the modification enables setting the material's biodegradation time according to the specific application needs.” Leppänen explains.
Different ways to control cellulose biodegradability
VTT has developed a new method to adjust cellulose degradability by chemically modifying paper. This proof of concept shows that targeting the fibre surfaces allows control over biodegradability and wet strength through precise surface acetylation. Higher modification increases resistance to degradation, but once the surface degrades, rapid biodegradation follows as the core remains unmodified. This technology ensures cellulose products resist immediate breakdown in soil and water. This method is applicable to various cellulosic objects, such as fibres, films, foams, aerogels, and paper.
A more conventional method to regulate the biodegradability of cellulose involves employing various crosslinking chemistries, commonly used in paper manufacturing to enhance wet strength. VTT has shown that by utilizing different crosslinkers, it is possible to control the degradation resistance of paper products.[2],[3] Such paper products can be applied in agriculture as mulching papers, which are a biodegradable option to non-degradable plastic mulches. With crosslinking, their resistance to biodegradation will increase and they can maintain their structure throughout the cultivation season but biodegrade afterwards unlike traditional plastics.
“Solid wood, composed largely of cellulose, can also be chemically treated to regulate its biodegradation rate. Through such modification, wood becomes resistant to biodegradation, making it suitable for use in contact with soil or in humid conditions that typically lead to rotting,” Leppänen says.
VTT is currently engaged in a Business Finland project called ‘PerfectWood’, which investigates the chemical modification of construction wood. Traditional wood preservatives, such as heavy metals and volatile organic compounds (VOCs), can leach out over time causing environmental hazards. However, the covalent modification method mitigates these emissions, whilst prolonging the life-time of the materials in the environment.
VTT has comprehensive capabilities in material development
VTT can scale up the production of materials, through piloting, and carrying out material testing under relevant conditions. We have strong expertise in evaluating biodegradability across various environmental conditions, including soil, compost (home and industrial), and aquatic conditions.[4] [5] Several standard and in-house test methods are available to assess the impact of tailoring on biodegradability of polymers, plastics, and packaging materials. In addition, biodegradation can be evaluated using a rapid enzymatic in-house method for fast screening of materials.
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[1] Leppänen, I., Vikman, M., Harlin, A. et al. Enzymatic Degradation and Pilot-Scale Composting of Cellulose-Based Films with Different Chemical Structures. J Polym Environ 28, 458–470 (2020). https://doi.org/10.1007/s10924-019-01621-w
[2] Korpela, A., Tanaka, A., and Asikainen, J. (2023). “Effect of chemical crosslinking on the biodegradation rate of kraft paper,” BioResources 18(3), 6336-6347.
[3] Korpela, A., Tanaka, A., and Asikainen, J. (2024). “Enhancing subsequent kraft fiber dewatering properties by using fiber polyamide-epichlorohydrin (PAE) treatment to prepare a dry pulp product,” BioResources 19(3), 5227-5238.
[4] Vikman, M., Mikkelson, A., and Rautkoski, H. The impact of lignin content on the biodegradation of virgin paper pulps in soil and marine environment, BioResources 19, 2, 2452-2465 (2024).
[5] Vikman, M., Vartiainen, J., Tsitko, I., Korhonen, K. Biodegradation and compostability of nanofibrillar cellulose-based products, J. Polym. Environ. 23, 206-215 (2015).
