The aim of experiment was to determine the optimal extraction process of hydrophobic extracts from black locust (Robinia pseudoacacia) and its influence on the black locust extract impregnated particles on corresponding properties of single-layer particleboards. Extraction was performed with distilled water, 50 % water solution of acetone (aq) and 50 % ethanol water solution (aq). The obtained extract was used for impregnation of spruce (Picea abies) particles, which were then used to make an 8 mm thick single-layer particleboard. Highest concentration of black locust extracts was gained from 50 % acetone (aq) and 50 % ethanol (aq). The smallest thickness swelling was determined in particleboard impregnated with acetone extract. The extraction was repeated using various sizes of black locust chips, namely size classes 1, 2 and 4, and 50 % acetone solution (aq). Research has suggested that particle boards impregnated with black locust extract, reduces swelling and emission of formaldehyde.
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