Liquid by-products from wood and forest industry find use in wood-plastic composites

A novel method for adding liquid by-products from the wood industry into wood-plastic composites (WPCs) prior to manufacturing was developed in a new study from the University of Eastern Finland. The study also discovered that proton-transfer-reaction mass-spectrometry (PTR-MS) is a suitable method for measuring the amounts of volatile organic compounds, VOCs, released from WPCs.

Wood-plastic composites – replacing plastics with wood

There is an increasing need to find new alternatives for crude oil based materials such as plastics. WPCs are natural fibre composites with properties of both plastic and wood. These composites are used, for example, in buildings and in the manufacture of automobiles. It is estimated that the production of WPCs will experience an annual growth of 14% between 2014 and 2019.

Wood and plastics are very different materials in terms of their chemical properties, which is why additives are used in WPCs to enhance the compatibility of these constituents. Additives are also used to improve composites’ water absorbing and weather resistance properties, among other things. However, some additives are rather expensive and their incorporation into WPCs is not straightforward. Thus, WPCs are in need of novel and effective additives that are based on renewable resources.

Putting waste to good use – liquids separated from wood as additives in WPCs

In the study, liquid by-products generated from biochar production and heat treatment of wood were added to WPCs, and the effects of the additions on the composite properties were analysed. The findings have relevance for two different industries as the wood industry by-products are more extensively used in the WPC industry.

The findings of the study show that liquids separated from wood can be added to WPC granulates using the method developed in the study. Composites treated with liquids performed better in injection moulding and the samples of each material type were very homogeneous. Furthermore, the addition of liquids extracted from wood significantly reduced the water absorption of the composites and in some cases improved their mechanical properties.

PTR-MS gives information about VOCs quickly

The study also examined the suitability of PTR-MS for analysing the amounts of VOCs released from WPCs. The advantages of the method include a short analysis time and the opportunity to monitor the release of VOCs in real time. The study suggests that PTR-MS is a suitable method for analysing the amount of VOCs released from WPCs.

Clear and consistent differences between different WPCs and amounts of VOCs released were found using PTR-MS. For example, significant amounts of VOCs were released right after manufacturing. The amounts of VOCs released grew after the addition of liquid by-products from biochar production and heat treatment of wood; however, the emission levels of harmful compounds did not increase to a level that would be hazardous.

The findings were presented by Taneli Väisänen, MSc (Tech), in his doctoral dissertation entitled Effects Of Thermally Extracted Wood Distillates On The Characteristics Of Wood-Plastic , which is available for download at http://epublications.uef.fi/pub/urn_isbn_978-952-61-2124-6/urn_isbn_978-952-61-2124-6.pdf

The findings were originally published in the European Journal of Wood and Wood Products, the Journal of Thermoplastic Composite Material, and the Journal of Wood Chemistry and Technology.

For further information, please contact: Taneli Väisänen, tel. +358445869472, taneli.vaisanen@uef.fi  

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About Us

The University of Eastern Finland, UEF, is one of the largest universities in Finland. The activities of the UEF underscore multidisciplinarity, and the university is especially strong in research related to forests and the environment, health and well-being, and new technologies and materials. The UEF offers teaching in more than 100 major subjects. In addition to the high standard of teaching, the university offers its students a modern study environment, which is under constant development. The university comprises four faculties: the Philosophical Faculty, the Faculty of Science and Forestry, the Faculty of Health Sciences, and the Faculty of Social Sciences and Business Studies. The university’s campuses are located in the heart of beautiful eastern Finland in Joensuu, Kuopio and Savonlinna. The UEF is home to approximately 15 000 students and nearly 2 800 members of staff.

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