Volume 11 Issue 4

Prepared test specimens were surface treated and coated with synthetic and water-based outdoor varnishes after being chemically impregnated. The test specimens were left outdoors to determine the effects of impregnation and treatment on the wood during each of the four seasons. Caucasian spruce (Picea orientalis L.) test specimens were prepared and combustion analyses were performed. As a result of the combustion test, weight loss results, as compared with the control, were 89% lower in the spring specimens, 90% lower with impregnation, and 90% lower with the synthetic varnish coating. Furthermore, the O2 amount during combustion was found to be the highest in combustion with a flame source in the winter specimens (21%). The CO2 amount was the highest in combustion without a flame source for full-year specimens (20%). The CO amount was the highest in combustion without a flame source of full-year specimens (31,787 ppm), and the NO amount was the highest during glowing of full-year specimens (55 ppm). Final results showed impregnation with Tanalith-E and water-based varnish coating to be the most effective fire protective treatments.

A simulated one-step process has been developed for the production of foam core particleboards using rigid polyurethane as the core layer. The results showed that the different techniques used for surface layer separation (unresinated particles and sprayed water) and foam injections (open system and closed system) had no influences on panels’ characteristics. Mechanical properties (e.g., bending strength and internal bond strength) were mostly influenced by the surface layer thickness, while the water absorption and edge screw withdrawal were influenced by the foam cell structure. The use of sprayed water for surface layer separation doubled the formaldehyde emission (FE) of the panels. The addition of urea (based on 10% of the dry resin) to the sprayed water had a positive effect of reducing the final FE. Furthermore, increasing the surface layer thickness had a positive, linear relationship with FE.

Humins are a major byproduct formed from acid-catalyzed biomass hydrolysis and are usually considered as a low-value material. In this work, humins were completely degraded by a two-step technology, involving alkaline-catalytic hydrothermal treatment followed by wet oxidation. Using this technology, humins were converted to value-added acetic acid for first time. The highest acetic acid yield of 25.6% on a carbon basis or 37.2% on a mass basis was obtained with a purity of 46.2% based on the organic carbon in the aqueous product. This high-efficiency recovery of acetic acid is a new method for the effective utilization of humins, which is an important finding for biorefineries.

Bamboo was converted into bio-oil via direct liquefaction with ethanol-phenol as solvent in a 250 mL Parr High-Pressure reactor. The influences of reaction parameters such as reaction time, liquefaction temperature, catalyst content, ratio of solvent/bamboo, and phenol concentration on the liquefaction yield were investigated. The highest liquefaction yield was 98.5 wt.% under the optimal conditions. The elemental analysis of the produced bio-oil revealed that the oil product had a higher heating value (HHV) of 29.5 MJ/kg, which was much higher than that of the raw material (16.4 MJ/kg). Gas chromatography mass spectrometry (GC-MS) and Fourier transform infrared spectrometry (FT-IR) measurements showed that the main volatile compounds in the crude bio-oil were phenolics and esters.

Lumber pieces usually contain defects such as knots, which strongly affect the strength and stiffness. To develop a model for rapid, accurate grading of lumbers based on knots, Douglas fir, spruce-pine-fir (SPF), Chinese hemlock, and Dragon spruce were used. The experiments explored the effects of modelling methods and spectral preprocess methods for knot detection, and investigated the feasibility of using a model built within one species to discriminate the samples from other species, using a novel variable selection method-random frog (RF)- to select effective wavelengths. The results showed that least squares-support vector machines coupled with first derivative preprocessed spectra achieved best performance for both single and mixed models. Models built within Dragon spruce could be used to classify knot samples from SPF and Chinese hemlock but not Douglas fir, and vice versa. Eight effective wavelengths (1314 nm, 1358 nm, 1409 nm, 1340 nm, 1260 nm, 1586 nm, 1288 nm, and 1402 nm) were selected by RF to build effective wavelengths based models. The sensitivity, specificity, and accuracy in the validation set were 98.49%, 93.42%, and 96.30%, respectively. Good results could be obtained when using data at just eight wavelengths, as an alternative to evaluating the whole spectrum.

To develop a smart, colour-changing wood material, photochromic microcapsules were incorporated into coatings while painting veneered plywood. The properties of microcapsules and coatings were investigated. The colour-changing behaviour of the photochromic wood material in response to sunlight exposure was evaluated. The microcapsules exhibited sensitive colour-changing function and had good thermal stability. The prepared photochromic wood material spontaneously altered its appearance from the veneer colour to a blue colour following intensity changes of the sunlight exposure on the sample. The incorporation of microcapsules had no obvious effect on coating adhesion, but it obviously reduced coating wearability. With the microcapsule content increasing from 2.5% to 10% (of the coating weight), the colour difference (ΔE) of photochromic wood stimulated by sunlight linearly increased from 7.45 to 21.58. The performance of the prepared photochromic wood material can be adjusted by controlling the addition amount of microcapsules.

This study investigated the effect of the positioning of the log before sawing on the volume yield of sawn timber from tropical hardwood species. Three positioning parameters were studied, the offset, skew, and rotation, combined with two sawing patterns of cant-sawing and through-and-through sawing. A database consisting of two tropical hardwood species with very different outer shapes, jambirre (Millettia stuhllmannii Taub.) and umbila (Pterocarpus angolensis DC.), was used to simulate the sawing process. The result of the simulation revealed that, according to the combined effect of offset, skew, and rotation positioning, the positioning of the log before sawing is extremely important to achieve a high volume yield of sawn timber. The positioning parameter that has the highest effect on the volume yield is the rotation, and the variation in the volume yield associated with a deviation in the positioning can reduce the volume yield of sawn timber by between 7.7% and 12.5%.

This article deals with the assessment of the influence of technical, processing, and material factors on selected mechanical properties and the granulometric composition of juvenile poplar wood chips. Individual analyses were made for two poplar species: naturally grown Populus tremula L. and the cultivated poplar clone Populus x euramericana “Serotina” for both juvenile and more mature wood. The main goal of this study was to evaluate the influence of the selected technical and processing parameters and of wood type (juvenile and more mature) on the chips’ granulometric composition during plane milling, its granulometric composition, and the sizes of the greatest and the smallest particles. Granulometric analysis (size test) was carried out to determine the share of the grain sizes for the individual wood fractions. While evaluating the granulometry, the influence of the milling process conditions as well as that of the wood’s physical and mechanical properties was taken into account.