The heat treated (HT) ThermoD and oil heat treated (OHT) samples were prepared for the test. ThermoD samples were prepared by treating wood with superheated steam and saturated steam. Oil heat treated samples were heat treated in oil under 180ºC and cooled directly in clean oil at the room temperature. During cooling the samples absorbed some oil. Untreated samples of pine, spruce and aspen were prepared as the reference samples.
The material was tested for 5 cycles. Each cycle contained: soaking in water for 24 hours, direct freezing for 6 days and direct warming for 30 minutes. The tested species were pine, spruce and aspen. Water absorption depended on type of species and treatment. Pine had higher water absorption but after oil heat treatment had the lowest water absorption due to high oil contain. Spruce and aspen had approximately the same water absorption. Heat treatment reduced water absorption as it was expected. Samples degraded in colour more or less and some started to crack. Almost all untreated and ThermoD treated pine samples cracked. Spruce had the highest visible change of the colour after the test. Aspen showed the best results because the colour did not change significantly and the material did not crack. Oil heat treated samples of pine lost some oil after the test.
Keywords: Wood waste recycling, MDF, Biological process
Authors
Sidorova E.
SP Wood Technology, Stockholm, Sweden
Morén T.
Division of Wood Physics, Luleå University of Technology, Skellefteå, Sweden
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