Volume 6 Issue 4

Effects of the impregnation materials borax, boric acid, and Tanalith-E on combustion properties of Oriental beech (Fagus orientalis Lipsky) were investigated. The immersion method was used for long-term impregnation (24 h). After the impregnation process, polyurethane as well as synthetic, acid hardening, and water-based varnishes were applied on the wood sample surfaces according to company’s suggests. The combustion test was performed according to the ASTM-E 69 standard. The mass reduction, release of gasses (CO, NO, O2), and the temperature differences of samples were determined for each 30 seconds during combustion. It was shown that the most mass reduction occurred when both polyurethane varnish and boric acid were applied.

The topochemical distribution of lignin and cellulose in individual cell wall layers of Populus nigra stem was determined by transmission electron microscopy (TEM) and confocal Raman microscopy. TEM images exhibited the fiber wall as being typically differentiated into three layers: middle lamella (ML), primary wall (P), and secondary wall (S1, S2, and S3). Higher magnification views showed the S2 layer to be differentiated into electron lucent and dense areas in the radial direction. In situ Raman images calculated by integrating over the intensity of characteristic spectral bands enabled visualization of the spatial variation in lignin and cellulose. Raman images acquired by integrating over the spectral band at 1605 cm-1 suggested that higher lignin content was visualized in the cell corner (CC), the compound middle lamella (CML), and the secondary wall of ray parenchyma. Cellulose distribution followed by taking the band regions around 2897 cm-1 into account showed the opposite pattern, with the highest content in fiber secondary wall. The SEM-EDXA provided semi-quantitative results, showing that the lignin content ratio in various cell wall layers was 1.4 (CC):1.1(CML):1(S2).

The bark of black spruce was thermo-mechanically refined and used to manufacture binderless bark-based fiberboard with various pressing temperatures, times, and panel structures in order to utilize an abundant bark resource for a better value-added application. The test results indicated that it is technically feasible to manufacture binderless fiberboard with refined black spruce bark through self-bonding under elevated temperatures over a reasonable period of pressing time. Binderless bark-based fiberboards with a homogeneous structure had very poor flexural properties due to the poor strength of bark itself; however, by using a sandwich structure with 30wt% wood fiber in the surface layers and 70wt% bark in the core layer it was possible to sufficiently improve panel flexural properties so that the manufactured binderless bark-based fiberboards was able to meet the mechanical property requirements of 115-grade fiberboard according to ANSI A208.2 (2009). Refining conditions had a great impact on the mechanical properties of binderless bark-based fiberboard.

Effects of drying temperature and artificial UV irradiation on the pH of veneer surfaces, water absorption, thickness swelling, as well as shear strength of plywood manufactured from untreated and treated veneer sheets were evaluated. Rotary cut veneer sheets from beech (Fagus orientalis Lipsky) log were selected. The veneer sheets were dried at either 100°C or 180°C after peeling. Then the surfaces were exposed to artificial UV irradiation in an UV chamber for 1, 2, and 3 days representing a natural sun irradiation of 2, 4, and 6 months, respectively. Tests by UV microspectrophotometry showed that after high temperature drying and UV irradiation treatment, lignin condensation occurs. Also with increasing drying temperature and UV irradiation duration phenolic extractives are mainly concentrated in parenchyma cells and vessel lumens. HPLC analysis of the treated tissue showed distinct signals of catechin and 2,6-dimethoxybenzoquinon, which are two chromophoric compounds in discolored red hearted beech wood. Increasing drying temperature up to 180°C improved water absorption, thickness swelling, and shear strength of plywood samples. Especially, when veneers were exposed to UV irradiation (6 months), increased water absorption and thickness swelling and decreased the shear strength of plywood samples were observed.

Fly ash was collected as a byproduct from the processing of southern pine wood chips in a pilot-scale biomass gasifier. General properties of the fly ash were determined to assess its applicability as a soil amendment. Its alkaline pH (9.5) and high concentrations of Ca, K, and Mg suggest that it could be used as both a liming agent and a fertilizer. The concentrations of most heavy metals in all ash samples in this study were lower than the ecological soil screening levels used as a guideline. A sequential extraction analysis was used to evaluate the bioavailability of selected nutrient elements and pollutant heavy metals in the fly ash. Most nutrient elements were present in exchangeable/acid extractable and easily reducible fractions. The heavy metals were generally less bioavailable, thus ameliorating concerns for land application of fly ash, with or without prior combustion. Comparison of sequential extraction test results for all of the ashes indicated that the conditions experienced during gasification, such as high processing temperatures, impacted both the total heavy metal concentrations and their potential bioavailabilities.

Preliminary tests of a new hydrogen peroxide bleaching procedure for mechanical pulps were performed in a bleaching medium comprised of water and an alcohol, which is characterized by good miscibility with water, poor solvency for hemicelluloses, and good solvency for lignin. As compared with a conventional bleaching method, this modified process is aimed at reducing the removal of hemicelluloses while moderately increasing the dissolution of lignin. Results showed that an aspen CTMP pulp can be bleached to a target brightness with less bleaching chemicals and/or with a higher pulp yield. The laboratory studies demonstrate that this new bleaching process offers substantially enhanced efficiency and selectivity over the conventional peroxide bleaching. Overall, the brightness increased by about 5 ISO units for a given peroxide consumption and the yield increased by 2 to 3 percent at the same target brightness.

Trees in two provenance-progeny experimental sites of Pinus brutia Ten. were sampled to study variation in wood density and its components among and within six populations and to estimate heritability of wood density and ring components. Wood increment cores (12 mm thick) were collected from 29-year-old trees at breast height. A total of 1023 wood strips were scanned with the X-ray densitometry technique. There were significant differences among populations and among families (within populations) in all the characters studied. Murtbeli (M) population from the middle altitude (486 m asl) had the highest values in both ring-area-weighted density and late wood proportion (500 ± 2.7 kg/ m3 and 49 ± 0.3 %, respectively), whereas Hacibekar (H) population from the highest altitude (1032 m asl) exhibited the lowest values (468 ± 3.0 kg/ m3, 42 ± 0.3 %). Relatively high heritability values (hi2 between 0.45 and 0.74; hhs2 between 0.68 and 0.80) for investigated characters (except latewood density) suggest that these characteristics are under moderate to strong genetic control, and thus, by selecting populations (and families within populations) having high wood density, genetic improvement can be achieved in P. brutia. Correlations between wood density and other growth traits have indicated that simultaneous selection of desired genotypes for most of the wood density components is possible for the species. Latewood percentage and earlywood density present an optimal target for selection to improve wood density.

Experimental binderless particleboards were made from various sizes of Rhizophora spp. particles. The experimental samples were made by cold pressing the particles to a target density of 1 gm/cm3. The internal bond strength and dimensional stability of the disks were evaluated based on Japanese standards. The experimental results showed that the internal bond strength and dimensional stability of the samples were enhanced as the particle size decreased. The microstructure of samples was investigated by field emission scanning electron microscopy (FE-SEM coupled with energy dispersive X-ray analysis (EDXA). An X-ray diffraction (XRD) procedure was used to study the crystalline structure of binderless particleboard samples. .

A novel reaction route was proposed from 5-hydroxymethylfuran-2- carbaldehyde (HMFCA) to 2-hydroxy-5-methylene-2,5-dihydro-furan-2-carbaldehyde (HMDFC) on the basis of the mechanism previously offered by Horvat, to account for the formation mechanism of levulinic acid. The probabilities of the two mechanisms were compared by Gaussian 03 software. It was found that the conversion from HMFCA to HMDFC in the newly deduced mechanism has a lower net energy requirement than that in the original mechanism, and thus should be more preferable. The mechanism indicates that HMFCA is initially protonized by H+ addition at the position 5 of the furan ring, and then combines with OH-, thereby completing the hydration process after isomerization. Finally, an H2O molecule is released, forming the intended intermediate product of HMDFC.