Maritime pine (Pinus pinaster) sawdust was used to produce liquefied wood by the polyhydric method with acid catalysis. The process was optimized to produce the highest amount of liquefied wood. Wood ...liquefied at 160ºC for 90 min was used in the adhesion tests. The bond strength of veneer glued with urea-formaldehyde and melamine-urea-formaldehyde resins and several mixtures of liquefied wood with urea- formaldehyde and melamine-urea-formaldehyde wasevaluated by automated bonding evaluation system.
With the increase in liquefied wood content the bond strength decreased. Nevertheless for 20% liquefied wood the reduction of internal bond strength is relatively small and still within the minimum standards required. When 70% of liquefied wood is employed there is a significant decrease in bond strength.
In conclusion it is possible to use a small amount of maritime pine sawdust liquefied wood as a partial substitute of urea-formaldehyde and melamine-urea-formaldehyde resins in the particleboard production, thus decreasing the formaldehyde content.
There are high amounts of post-consumed protected waste wood removed from service every year. The residual biocides, including copper, chromium and boron from CCB (Cu, Cr, B) in post-consumed wood ...that was protected with biocides may cause environmental problems during waste management, for example during land filling. Therefore, the aim of this study was to find out if Cu and Cr in the processed waste wood, previously treated with CCB, can be re-used as a wood preservative or in coatings made of liquefied wood. Liquefaction of CCB containing waste wood could be as well the first step in the elimination process of metals. So, the optimal conditions for liquefaction of CCB (Cu, Cr and B) containing black poplar (Populus nigra L.) wood were established and compared with liquefaction of uncontaminated black poplar wood. The reactants for liquefaction of black poplar wood sawdust were ethylene glycol (EG) and sulphuric acid. It was observed that in the last stages of the liquefaction process, the presence of Cu, Cr and B did not have any influence on liquefaction yield (LY), while their influence was observed in first stages of the solvolytic reaction. Investigations of fungicidal properties of uncontaminated and CCB containing liquefied wood showed higher antifungal efficacy of liquefied wood without Cu, Cr and B than of liquefied wood that contained CCB. In the tested concentration range, the presence of Cu even promoted the growth of selected wood decay fungi. One of the reasons for higher toxicity of liquefied black poplar sawdust without Cu, Cr and B, was its very low pH value.
The aim was to optimize the liquefaction conditions of
wood flour with polyethylene glycol (PEG#400) as the solvent in the presence of sulfuric acid as a catalyst under atmospheric pressure. Reaction ...time (30–180 min), temperature (130–170°C), and the solvent ratio (PEG/glycerol=0–25%) were varied to obtain the lowest residue content. The resulting polyol was characterized by their hydroxyl number (OHN), acid number (AN), viscosity, molecular weight (M
), thermogravimetric analysis, Fourier transform infrared (FT-IR) and two-dimensional correlation spectroscopy (2D-COS). The OHN was lowered, AN and M
were elevated as a function of increasing the reaction temperature and the time. Introducing glycerol in the PEG system markedly increased the OHN, AN and viscosity of the liquefied wood. The optimum condition was 80/20% ratio of PEG/glycerol at 150°C in 150 min leading to a 75% liquefaction yield. The 1730 cm
band was indicative for the esters in the liquefied product. The 2D-COS analysis showed that lignin is easily liquefied at high temperatures and a decreasing amount of PEG, and that the presence of glycerol significantly enhanced the 1730 cm
band.
Wooden activated carbon fibers (WACFs) were prepared from phenolated Chinese fir (
Cunninghamia lanceolata
) using CO
2
activation; microstructure characterization, the adsorption capacity, ...BET-specific surface area, and pore distribution of WACFs were investigated by SEM and X-ray analysis. Results showed that WACFs have a smooth surface and round or elliptical cross-section. The (002) crystal plane diffraction peak of the WACFs was obviously heightened, also showing an apparent (100) diffraction peak. With increased activation temperature, the value of
d
(002)
gradually decreased, whereas the values of the crystallite sizes
L
a
and
L
c
initially decreased and then increased. The
L
c
/
d
(002)
and
g
values corresponding to the degree of change in the graphitization structure increased. WACFs mainly have micropores as well as a few macro- and mesopores. The micropore diameter of WACFs has a narrow range (0.3–0.5 nm). With increased activation temperature, the single-point surface area, Brunauer-Emmett-Teller surface area, micropore area, single-point total pore volume, and micropore volume of WACFs increased, while the pore diameter decreased. At 900 °C, the iodine adsorption and yield rate of WACFs were 779.22 mg/g and 51.48 %, respectively.
The thermal behavior of liquefied wood polymer composites was characterized by means of thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. Low-density polyethylene (LDPE), ...high-density polyethylene (HDPE), and polypropylene (PP) as polymer matrices were used with liquefied wood (LW). HDPE showed a better thermal stability than PP. Melt index did not show a significant effect on the thermal stability. The thermal stability of LW decreased with the increase of LW content up to 40%. Higher heating rate provided the higher thermal stability, resulting from the decelerated decomposition rate. According to DSC analysis, the melting temperature of HDPE decreased with the increase of LW loading level. The melting temperature of virgin LDPE and HDPE decreased with the addition of 10% LW. The melting temperature of virgin PP also decreased with the addition of LW. Enthalpy of virgin polymers also decreased with the addition of LW. This study proves the thermal stability necessary for the consolidation process of composite materials.
The aim of the presented work was to replace phthalate based plasticizers with environmentally friendly materials to provide similar properties for poly(vinyl acetate) (PVAc) adhesives.
Polyesters ...synthesized from the liquefied wood (PE-LW) and depolymerized polyethylene terephthalate (PE-PET) were used as renewable raw materials and evaluated as plasticizers used in PVAc dispersion adhesives for flooring applications. As a reference plasticizer, 1,2,3-triacetoxypropane was used.
PVAc adhesives were evaluated with respect to solids content, viscosity, glass transition temperature (Tg), tensile shear strength and binding strength.
TGA analysis showed significant differences between the thermal stability of added polyesters and the commercial plasticizer. Samples prepared with PE-PET exhibit the best thermal stability even with an increase of 25% PE-PET. The addition of coalescing agents or plasticizers leads to a temporary softening of the PVAc polymer and a decrease in the glass transition temperature.
The type and content of plasticizer have great influence on wood–wood binding strength, tensile strength and elongation.
The requirements for the mechanical properties of adhesives were fulfilled by the compositions containing 8.8% (w/w) of PE-PET and 20% (w/w) of PE-LW.
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