Martins Andzs

Utilization of lignin powder for manufacturing self-binding HDF

Abstract 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.

Biomass conversion into blow-in heat insulation materials by steam explosion

Abstract The study of converting grey alder (Alnus incana) chips and silver birch (Betula pendula) flakes – residues from plywood manufacture – into blow-in insulation material by steam explosion (SE) is reported. The SE was conducted at temperatures between 200 and 235°C, for 0–5 min at pressures between 16 and 32 MPa. The severity parameters (logR0) of the SE was calculated, from which logR0≈3.6 was the most appropriate for production of blow-in materials. Thermal conductivity of the obtained insulating material was found to be in the range of 0.053–0.057 W m−1·K−1.

STEAM EXPLOSION AS A PRE-TREATMENT METHOD FOR BIO-REFINED HYBRID ASPEN LIGNOCELLULOSE

Steam explosion (SE) is a well renowned pre-treatment method used for bio-refined material synthesis due to its simplicity in machinery and efficiency in resource and energy use in creation of high-value products. Used for separation of lignocellulose originated from wood and other sources, current research in wood-based lignocellulose has mainly focused in separation of wood fractions from commonly grown tree species. Scientific studies are needed for better understanding of common tree species to generate new possible products, e.g., bio-based composite materials. Commercially grown hybrid aspen ( Populus tremuloides x Populus tremula ) was pre-treated by SE to obtain a nano-level structured cellulose and lignin for bio-based composite materials. The results present a yield of extracted cellulose and lignin depending on SE conditions (severity factor) and subsequent water/alkaline extraction. Extractions have been executed with and without heat treatment. The research reveals a positive correlation between the yield of extracted lignin and SE severity factor, and a negative correlation for SE cellulose. The study concludes that SE hybrid aspen is proving to be a promising source for extraction of cellulose and lignin for bio-based composite materials.

Zero Emissions and Bio-refineries for Natural Fibres, Biomaterials and Energy: Genesis of Concepts. Review

Depletion of world recourses, increasing pollution, and climate change make us to shift from linear economy to system economy—an economy of technologies integrated to reach a system of non-polluting zero emissions production. Transition to renewable resources requires replacing the present crude oil refinery by biomass refinery. Along with conventional biomass refinery technologies bioengineering and nano-technologies become significant players in systems designed as clusters of integrated bio-refinery technologies. The authors consider a number of case studies of biomass conversion into value-added chemicals and sources of energy, the steam explosion auto-hydrolysis (SEA) in particular. Research of wood and non-wood (hemp, etc.) fibres demonstrates feasibility, for example, of value added textiles, self-binding bio-composite boards, heat insulating micro- and nano-materials. Serious breakthroughs require revision of the structures of fundamental natural macromolecules, particularly the complexity, scaling and fractality of lignin.