Black poplar wood, diethylene glycol (DEG), and sulphuric acid as a catalyst were used as starting reactants for liquefaction. Optimal conditions for liquefaction were established: reaction temperature 150 °C, reaction time 95 min, ratio of wood:DEG = 1:5 and 3% of sulphuric acid addition. The liquid mixture obtained by the liquefaction was composed of the real product of the reaction (the so called Ćexcess solvent free liquefied woodĆ (ESFLW)) and of the remaining unreacted DEG. The unreacted DEG was successfully separated from the ESFLW and analysed with HPLC for levulinic acid content. Theoretical weight ratio between the wood and DEG required for the reaction was estimated.OH number investigation showed that the ESFLW in the liquid mixture contributes to maximally 60% of the free OH groups. The crosslinking of the ESFLW without any curing agents or additives was performed for the first time,and the drying stages investigated. FT-IR investigations demonstrated that the obtained crosslinked polymer film could be an ether and/or ester network.
COBISS.SI-ID: 1703049
Recovered wood is frequently contaminated with biocides and therefore its use is limited. Even more, wood, impregnated with classical chromated copper arsenate (CCA) preservatives is classified as a hazardous waste, therefore solutions for reuse or recovery of this material are sought. One of the options, discussed in this paper is liquefaction and further applications of liquefied wood containing biocide remainings. In order to elucidate this possibilty, spruce and beech wood was impregnated with liquefied CCB treated and untreaded spruce wood of various concentrations and exposed to wood decay fungi according to the EN 113 procedure. In paralel, the leaching experiments (ENV 1250-2) were performed as well. The results do not clearly show that liquefied wood is bio-inactive. In most cases the mass loss by fungal attack is decreased compared to the untreated controls. On the other hand, copper leaching from spruce wood, impregnated with the liquefied CCB treated wood was significantly reduced. Thus, there are indications that the liquefied wood could be utilized as a binding agent for inorganic biocides.
COBISS.SI-ID: 1957257
The liquefied biomass resulting from various liquefaction processes developed up to now is of a dark-brown or even black colour. This intense colouration could limit its use as an intermediate for the production of bio-based materials (plastics, adhesives or coatings) due to aesthetic reasons. In this study, bleaching of liquefied wood using various hydrogen peroxide and laccase model systems was investigated. The Fenton reagent, iron(II) activated hydrogen peroxide, showed low efficacy (degree of discolouration less than 25%) in the range of hydrogen peroxide concentration applied. On the contrary, the degrees of discolouration of up to 71% and 80% were obtained with copper(II)/pyridine and potassium carbonate activated hydrogen peroxide, respectively. Attempts to use a green enzymatic process, with laccase from Trametes versicolor (EC 1.10.3.2) and eventually a redox mediator (2,2-Azino-bis-(3-ethylbenthiaoline- -sulfonate) diammonium salt or 1-hydroxybenzotriazole), which extend the activity of laccase to non-phenolic substrates, were unsuccessful. FT-IR analyses, weight loss, hydroxyl number and viscosity measurements showed that it was possible to lighten liquefied wood to a certain extent (Delta E* up to 38) without drastic degradation of the material. Liquefied wood, initially a dark-brown material, could be converted into a transparent orange product whose colour could be further modified with dyes and pigments for the production of biomaterials.
COBISS.SI-ID: 2064777
Reducing boron leaching from impregnated wood has been one of the most challenging tasks for at least 50 years. In order to slow down the leaching of boron, aqueous solutions of boric acid were combined with liquefied spruce wood. The results clearly showed that leaching of boron from spruce wood impregnated with preservative solutions based on boric acid and liquefied wood was significantly reduced.
COBISS.SI-ID: 1881993
The bonding of beech (Fagus sylvatica L.) with liquefied wood (LW) causes deterioration of the wood surface, resulting in a high percentage of wood failure at a relatively low bond shear strength. Light microscopy, scanning electron microscopy, FT-IR micro-spectroscopy and elemental carbon, nitrogen and sulphur (CNS) analysis techniques were used to investigate the formation of such bonds. It was assumed that the degradation of lignin, hemicelluloses and parts of the cellulose occurred in the cells of the wood surface where the LW had been applied. At the elevated temperatures occurring during the bonding process, the deteriorated cells were carbonised to some extent. The weak boundary layer of the bond was determined to be a layer of delignified cells located between the zone of partly carbonised cells on the one side and the cells of the undamaged wood of the adherend on the other side. The bonds which formed during the bonding of wood with LW were found to be very untypical compared to bonds formed by synthetic wood adhesives. No adhesive film was formed, the adhesive-adherend interface was not clear and the cells of the adherend subsurface were damaged.
COBISS.SI-ID: 2058889