Volume 10 Issue 4

Wood-based materials are used to manufacture various types of panels, including particleboard, fiberboard, and plywood, and they can also be used to manufacture furniture as well as interior and exterior building materials. However, wood-based materials exhibit a number of problems, including the emission of indoor air pollutants from adhesives used during production and their inherent fire risk. To date, a number of studies have investigated the emission of indoor air pollutants, and in recent years, there has been an increasing amount of interest in the flame-retardant performance of wood-based materials. In this study, the use of carbon materials was studied to improve the flame-retardant performance of wood-based materials. A comparison was made with various methods that are currently in use. The thermal conductivity was measured by the TCi method developed by C-Therm Technologies Ltd to evaluate the energy characteristics of wood-based materials that are used as interior materials.

Rosewood furniture and handicrafts are appreciated by Chinese people on account of their rich aroma and pleasing feel. The unique characteristics of rosewood are attributed to the presence of certain organic compounds in its gum canal and parenchyma cells. However, modern wood drying is different from traditional technology with respect to protecting those valuable organic compounds in wood. In this study, to investigate the valuable organic compounds in Dalbergia bariensis, and the effect of drying treatments on their preservation rates, wood extracts, untreated and treated with conventional drying (CD), vacuum drying (VD), and vacuum freeze drying (VFD), were analyzed by gas chromatography- mass spectrometry (GC-MS). The results indicated that there were some compounds with obvious pharmaceutical functions in Dalbergia bariensis, which can be used to improve the furniture function in health care. Also, the preservation of these compounds was affected by drying treatment; VFD drying preserved the maximum amount of organic compounds in wood.

The cellulolytic and ethanologenic bacterial community is a promising candidate for the production of bioethanol from lignocellulose. In this study, by artificially changing the ratio of Clostridium thermocellum in the cellulolytic consortium H, ethanol production was increased by 72.7%. Metatranscriptomic analysis was used to elucidate the contribution of Clostridium thermocellum to ethanol production. A comprehensive analysis of genes mapped to the Clostridium thermocellum ATCC 27405 genome was performed; the identified gene expression differences related to cellulosic ethanol pathways were carefully studied. The results indicated that the majority of genes involved in lignocellulose degradation, sugar transport, cellodextrin breakdown, glycolysis, and ethanol synthesis were up-regulated in C. thermocellum when added to H (HCt). More than 18 cellulosome-related genes had 15-fold or greater increased expression. The results illustrate the role of C. thermocellum in the cellulolytic consortium H and HCt and provided useful information for identifying genes and preferred pathways. These results will aid in the metabolic and genetic engineering of bacterial strains for more efficient biofuel production.

The article deals with the influence of the tool wear of several circular saw blades, each with different numbers of teeth (24, 40, and 60), on the quality of a machined wood surface. The surface quality was evaluated based on the surface roughness, which was represented by the surface arithmetical mean deviation Ra. To achieve the conditions of manual sawing, the saw blade was shifted into the cut with a constant feed force of 15 N. The results showed that the 40-tooth saw blade obtained the most suitable results; it exhibited the longest sawn distance and reached moderately good values of tool wear. The average values of surface roughness ranged from 3.9 to 14.5 µm, and the saw blade wear increased proportionally with sawn distance. The tool wear of the saw blade had no unambiguous effect; increase in tool wear did not lead to a deterioration of surface quality.

The objective of this work was to extract and bleach cellulose from a low-value agricultural waste, namely, olive tree branches. The extraction procedure began by subjecting finely powdered olive tree branches to alkaline treatment, using different concentrations of sodium hydroxide solution to remove/dissolve the non-cellulosic cementing constituents, such as pectin, hemicelluloses, and natural waxes from the structure of this lignocellulosic network. The second step of the extraction procedure was the oxidation/bleaching treatment, and for this purpose, a powerful oxidizing agent composed of sodium chlorite/triethanolamine salt was used. All factors and conditions affecting the bleaching reaction, including triethanolamine salt concentration, bleaching temperature, and utilization of different triethanolamine salts, were extensively studied. The efficiency of the bleaching/oxidation treatment was evaluated by recording the FTIR spectra of the samples before and after extraction and analyzing the bleached samples to estimate the carboxyl content, loss in weight, and whiteness index.

This study investigated the effects of heat treatment, following optional treatment with synthetic, water-based, and alkyd varnishes, on the pull-off strength of wooden materials sampled from oriental beech (Fagus orientalis L.), oak (Quercus petraea Liebl.), black poplar (Populus nigra L.), pine (Pinus sylvestris L.), and fir (Abies bornmulleriana M.). The test samples were subjected to heat treatment at temperatures of 165 °C and 175 °C for periods of 2 and 4 h with a total of 4 variations. With respect to the wood type, the samples of beech wood yielded the highest results for pull-off strength, while fir wood yielded the lowest. With respect to the varnish types, the highest pull-off strength was found in the samples of synthetic varnished beech (5,452 with a 37.2% improvement) at 175 °C heat treatment for 4 h, while the lowest results were obtained in the samples of fir (0.991 with a 48.5% decrease) at 175 °C heat treatment for 4 h. In conclusion, heat treatment significantly decreased the pull-off strength of the woods.

The coupling of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry with 13C nuclear magnetic resonance (NMR) is a suitable method for examining the composition of hydrolysable tannins and has been applied to the investigation of valonia oak (Quercus aegylops) acorn tannin extract. Such methods can determine the extract’s structural aspects and other characteristics. It was determined that valonia oak acorn tannin extract is composed of mainly pentagalloylglucose structures; their rearrangement structures, vescalagin/castalagin (with linkages to flavogallonic acid) and vescalin/castalin; ellagic acid and vescavaloneic/castavaloneic acid; and free gallic acid and glucose. Traces of catechin gallate were also observed in this tannin extract. The tannin from acorns of valonia oak was used to substitute up to 50% of the phenol used in the preparation of phenolic resins as adhesives for wood particleboard. These phenol-tannin-formaldehyde resins showed comparable performance to phenol-formaldehyde resins.

Material flow analysis (MFA) was applied to study the process of biogas production from switchgrass using a mid-temperature (35 ± 1 °C) batch anaerobic digestion process. The flow distributions of energy and material, including carbon (C) and nitrogen (N), were analyzed, as were the material and energy conversion efficiencies. The results showed that biogas and CH4 production were 268.80 and 135.31 NmL×gVS-1 added, respectively, and the average CH4 content in biogas was 50.34%. Based on the MFA of the anaerobic digestion process, 30.6%, 3.6%, and 65.8% of C was converted into biogas, biogas slurry, and biogas residue, respectively; and 11.7% and 88.3% of N was converted into biogas slurry and biogas residue, respectively. The conversion efficiencies of the material and energy from switchgrass to biogas were 36.1% and 30.1%. Because of the low conversion efficiencies of matter and energy during biogas production, it is necessary to strengthen the secondary use of the fermentation residue. This study provides a basis for the optimization of the anaerobic digestion process and efficient utilization of resources and energy of energy-grass.

The influence of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) on the properties of ground calcium carbonate (GCC) and clay coating colors, as well as its effect on curtain stability during the coating process was investigated. Based on the experimental results of the zeta potential, sediment porosity, rheological measurements, the floc formation mechanisms of the cobinders were proposed. The zeta potential decreased with an increase in the amount of added PVA, while it barely changed when CMC was added. This was attributed to the adsorption of PVA onto the pigment surface, while the adsorption of CMC was hindered by electrostatic repulsion. CMC cobinder increased the low-shear viscosity, but it resulted in relatively low viscosity under high-shear conditions, indicating the disruption of the formed flocs under high shear. The destabilization mechanism of the curtain coating differed depending on the type of cobinder. The PVA cobinder flocculates the coating color via a gelling mechanism, while the CMC cobinder flocculates the colors via a depletion flocculation mechanism.

This study examined the color stability of painted Norway spruce (Picea abies) samples subjected to natural and accelerated weathering, using Duncan’s tests and correlation analyses. The following effects were studied: (1) the different initial roughness of the wood; (2) use of transparent or lightly-pigmented top-coat layers; and (3) the presence of the final water-repellent layer. Natural weathering at a 45° slope in an industrial zone lasted 104 weeks, whereas accelerated weathering in Xenotest with 0.55 W/m2 UV irradiation at 340 nm and sprayed water lasted 12 weeks. The color stability of painted spruce, measured in a CIE-L*a*b* system, was not, in the majority of cases, significantly affected by the initial roughness of the wood, the type of top-coat (WoodCare UV or PerlColor) layer, or presence of the final water repellent (AquaStop) layer. The light pine or larch pigments in the top-coat layers had positive color stabilizing effects. In their presence, the darkening (-DL*) and total color differences (DE*) of the painted samples dropped ca. 2.5 times during exterior weathering and ca. 5 times during Xenotest weathering. Samples painted with transparent coatings turned a reddish shade (+a*) during the Xenotest, while those exposed to the exterior absorbed dirt and became more blue (-b*).