Forest4LV results: from bio-based feedstocks to higher value-added materials
The scope of research carried out within the National Research Programme Forest4LV extends beyond forest ecosystem protection to include the processing and conversion of forest resources into higher value-added products. This second article in the series focuses on three studies that examine forest biomass as a multifunctional feedstock in wood chemistry, biorefining, and the development of new materials.
The studies highlight different stages of forest resource utilisation, ranging from the chemical transformation of birch bark and lignocellulosic fractions to the development of bio-based polyurethane foams and environmentally friendly plywood. What unites these works is the search for scientifically grounded technological solutions that enable more efficient use of local forest resources, reduce reliance on fossil-based raw materials, and expand the industrial applications of wood.
In the study presented by Ph.D. Aiga Ivdre, birch bark suberin depolymerisation fractions (SA1, SA2, SA3) were evaluated and their effects on polyol properties, as well as on the mechanical strength, thermal stability, and flammability of the resulting rigid polyurethane (PU) foams, were assessed. Polyols were synthesized using suberinic acids, tall oil fatty acids or epoxidized tall oil fatty acids, and trimethylolpropane Several alternatives have been tested to replace the widely used but carcinogenic flame retardant tris(1-chloro-2-propyl) phosphate (TCPP).
A visual summary of the results of the study "Development of Rigid Polyurethane Foams from Suberinic Acids and Tall Oil–Based Products".
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Authors: Ph.D. Aiga Ivdre, Ph.D. Daniela Godiņa, Mg.chem. Arnis Āboliņš, Mg.chem. Laima Vēvere, Ph.D. Miķelis Kirpļuks, Mg.sc.ing. Rūdolfs Bērziņš, Dr.chem. Māris Lauberts, Dr.sc.ing.Jānis Rižikovs.
Key findings:
- The SA1 fraction (obtained at pH=1) showed the highest yield, whereas SA3 (treated with FeCl3) polyols had the lowest viscosity, facilitating their use in foam production.
- The obtained PU foams exhibited an apparent density of 40–45 kg/m³ and thermal conductivity of ~20 mW/(m·K), indicating suitable thermal insulation performance.
- Flammability characteristics did not differ significantly between fractions; however, the SA2 system showed lower thermal stability.
- The addition of SAR filler (up to 12%) increased the share of renewable raw materials while maintaining the mechanical and thermal properties of the foam.
- Triethyl phosphate proved suitable as a substitute for TCPP, ensuring improved processability of the reaction mixture.
The results provide a substantiated assessment of the effect of suberinic acids obtained under different conditions on the properties of bio-based PU foams.
In the study presented by Dr.sc.ing. Māris Puķe, the phosphoric-acid-based pretreatment of birch veneer chips was evaluated with the aim of selectively converting hemicelluloses into furfural-containing products while retaining the cellulose fraction in the lignocellulosic residue.
Experiments were conducted on a pilot-scale unit (TRL 6), systematically varying temperature, reaction time, catalyst loading, and steam flow rate.
A visual summary of the results of the study "Biorefining Technologies for Integrated Utilisation of Forest Resources to Produce Higher-Value Products".
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Authors: Mg.sc.ing. Māris Puķe, Dr.sc.ing. Prans Brazdausks, Ph.D. Daniela Godiņa
Key observations:
- Acetic acid yields reached 97.57–100% of the theoretical maximum.
- Furfural yields were 8.75–10.41% (dry basis), corresponding to 56.81–67.59% of the theoretical yield.
- Cellulose losses ranged from 5.69% to 0.64%, indicating selective hemicellulose degradation with minimal C6 carbohydrate loss.
- A 5-HMF yield of 36.84% from the lignocellulosic residue was obtained.
- Tested process conditions: 155–175 °C, reaction time 30–70 min, catalyst loading 2.5–5.5%, steam flow 80–120 mL/min, phosphoric acid concentration 55% (see process scheme in the poster).
These results quantitatively characterise the efficiency of phosphoric-acid pretreatment for furfural production and cellulose preservation, and identify the process parameters that ensure high selectivity in lignocellulosic biorefining schemes.
While the study presented by Dr.sc.ing. Māris Puķe marks an important stage in the forest resource conversion chain by demonstrating how selective processing of lignocellulose can yield high-value chemical intermediates with potential for further use, the study presented by Dr.sc.ing. Ramūnas Tupčiauskas examined the production of particleboard using pine long shavings and recycled furniture particles in combination with a suberinic acids (SA) bio-adhesive. The influence of raw material type and panel density on mechanical properties, moisture resistance, and adhesion performance was evaluated.
A visual summary of the results of the study "Bio-based Wood Composite for Furniture and Construction Applications".
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Authors: Dr.sc.ing.Ramūnas Tupčiauskas, Mg.sc.ing. Andris Bērziņš, Mg.sc.ing. Rūdolfs Bērziņš, Ph.D. Mārtiņš Andžs
Key observations:
- The SA bio-adhesive ensured effective bonding for both particle types; sufficient adhesion and moisture resistance were confirmed (see swelling data in the poster).
- Mechanical properties correlated strongly with density: panels with a density of 650 kg/m³ showed lower performance regardless of particle type.
- Panels made from recycled particles exhibited higher bending strength and screw-withdrawal resistance (see table in the poster).
- Several physico-mechanical parameters partially complied with the requirements of LVS EN 312, P2.
- A furniture carcass prototype was produced to assess applicability at TRL 5.
The results provide a data-based assessment of the applicability of SA bio-adhesives in particleboard production and identify key directions for further optimisation of mechanical performance.
