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The preparation of self-binding lignocellulosic fibreboards has been investigated. Different high-density fibreboards (HDF) were hot-pressed based on a mixture of grey alder (Alnus incana L. Moench) wood chips processed by steam explosion auto-hydrolysis (SE) and 15% or 25% lignin content from three different industrial sources: softwood kraft lignin (SWKL), soda wheat straw lignin (SoWhStL) and hydrolysis wheat straw lignin (HWhStL). Density, thickness swelling (TS) after immersion in water for 24 h, modulus of rupture (MOR), modulus of elasticity (MOE) and strength of internal bond (IB) of the board samples were determined. The amount (15% or 25%) and moisture content (MC) (18±1% or 5±2%) of the added lignin affected all the tested properties of the HDF except for density. However, the kind of the added lignin affects the obtained fibreboard more significantly compared to the control sample made without an admixture of lignin. In some cases, the tested values were diminished to half. The tested properties of the HDF samples produced with SoWhStL or HWhStL are compatible with standard requirements for medium-density fibreboard (MDF) for general use under dry conditions (EN 622-5, MDF), however, it depends on the lignin amount and MC.

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Some industrial crops residuals like wheat straw, buckwheat husks and reeds were used in the study as raw lignocellulosic materials to evaluate their potential as thermal insulation material. Steam explosion (SE) pre-treatment was used to disrupt and convert the raw material smooth shape to foamy fibrous shape. Two level Factorial design was used to evaluate the impact of raw material fraction size (10-20-30 mm), moisture content (10-30-50%), SE temperature (200-215-230 °C) and duration (00-30-60 s) on bulk density and thermal conductivity of the obtained loose-fill materials. The results show that all selected raw materials could be characterized as thermal insulation materials as the determined thermal conductivity was in the range of 0.042–0.058 W (m K)-1 including neat samples. In spite of effective fibrillation of raw materials SE pre-treatment did not improve their thermal conductivity. The determined bulk density of loose-fill crops varied in range of 23–184 kg m-3 depending on all variables; the SE pre-treatment showed the most significant effect on its reduction. Based on the study results the most suitable crops residues for bio-based thermal insulation purposes are suggested wheat straw and reeds demonstrating the lowest values of bulk density and thermal conductivity.