The chemical compositions and structural characterizations of bamboo samples with three pretreatments using sand bath to heat were comparatively studied with Fourier infrared spectrum (FTIR). The results showed that the holocellulose and cellulose yields increased significantly and the dilute alkali (NaOH) pretreatment performed better lignin removal rate than that of dilute acid (H2SO4) and glycerin pretreatments.Furthermore, when the same solutions were used, the compositional changes were more remarkable at 135 than at 117°C, and the similar degradation of hemicelluloses was observed for the different pretreatments. With sodium hydroxide at 135°C, compared to un-treated bamboo, cellulose increased by 14.21 % and hemicellulose decreased to 13.98 %, counting the removal of lignin to 20.29 %. In which, the bamboo expressed the betterdelignification with sand bath and higher temperature and combinations with other methods of glycerin pretreatment should be evaluated in the future work.
The current study about physical properties of wood of Quercus robur L., Q. petraea (Matt.) Liebl., and Q. pyrenaica Willd. in Galicia (northwest of Spain) was based on the determination of proportion of sapwood, heartwood, infradensity, and porosity to understand and estimate the variation of these characteristics and/or properties in the Galician oaks. For this, it was necessary to fell several trees within the study area. In total, 45 trees were chosen in 15 different stands of provinces of Lugo and Ourense, i.e., we have obtained 45 wood slices of Quercus at 60 cm tall on the trunk of the tree, and 194 wood samples with a parallelepiped shape and dimensions of 2×2×4 cm ± 1 mm. The infradensity characterization reveals that oak wood from Galicia has a greater infradensity than French oaks, and Quercus pyrenaica has a higher infradensity than Q. robur and Q. petraea. There is a strong variation of the same based on the geographic origin, but there is almost no variation inside a plot. The global objective was to realize a detailed description on the physical properties of wood of these species for its possible use in industry cooperage. For this, the objective of this initial work was to begin with the study of wood infradensity.
The effect of water prehydrolysis conditions, which was used as the first stage of wheat straw pretreatment, on the composition of filtrates was analysed. Many of the substances that are present in the prehydrolysis filtrates are broadly used and thus they contribute to improvements in the efficiency of bioethanol production. Prehydrolysis was carried out at temperatures of 140, 160 and 180°C and times of 30, 60 and 120 min. Xylose and its oligomers were the most represented in prehydrolysis filtrates, their yields increased up to 12.1 % with increasing weight of wheat straw removed up to 28.6 %. Besides xylose and glucose, acetic acid, formic acid and the phenolic compounds were also present in the prehydrolysis filtrates. At 160 and 180°C, levulinic acid and furfural and hydroxymethylfurfural, respectively, were also present. The solid fractions of wheat straw were subjected to steam explosion under the same conditions at 200°C for 2 min. Two-stage pretreated wheat straw was subsequently enzymatically hydrolysed. The conditions of water prehydrolysis combined with steam explosion pretreatment had a significant effect on the results of enzymatic hydrolysis of wheat straw. The conversion of cellulose increased with increasing prehydrolysis temperature and time from 64.8 to 91.7 %. Similar results were observed for the conversion of xylan from 73.7 to 92.4 %. With increasing of prehydrolysis temperature and time, the amount of inhibitors in hydrolysates decreased. The recommended conditions for water prehydrolysis at two-stage pretreatment of wheat straw correspond to temperature of 160°C and time of 60 min.
The demand for partially harmless dyes produced from natural sources as an alternative to synthetic dyes has been increasing. Natural dyes environment and they are attractive materials contributing to the protection of natural balance and to the reduction of aesthetic concerns of people. Yet, for natural dyes to be long-lasting and cling to the surface, they need to be used with mordant substances. In the present study, the purpose is to determine the antifungal and antibacterial activities of natural dye obtained from pomegranate skin by means of ultrasonic. Plant extract obtained through ultrasonic method was applied to oriental beech (Fagus orientalis L.) and yellow pine (Pinus sylvestris L.) wooden materials by means of dipping and ultrasonic-assisted immersion. For the analysis of the results, data obtained from the natural dye were compared with those obtained from the synthetic dye. The findings of the analysis revealed that the most effective results in terms of antifungal activities were obtained from the solutions applied to yellow pine wood. For beech samples, the natural dye yielded better results when compared to the synthetic dye. Moreover, pomegranate skin solutions were found to prevent the spread of antibacterial activities. As a result, it was concluded that pomegranate skin extract can be used as wood preservative and coloring materials by mixing with holding provider.
Effects of dye concentration, dyeing temperature and time, volume ratio, and dyeing assistant and fixing agent, fixing time on the dye-uptake and K/S were investigated with orthogonal experiments. The major factors on dye-uptake and K/S were identified using visual and variance analysis. Dye-uptake and K/S were synthetically evaluated and optimally selected with fuzzy comprehensive evaluation. Results showed that dye concentration and temperature were significantly affected by all the seven factors during dyeing process on dye-uptake and K/S. The optimal parameters for the dye effect of maple veneer were: temperature 65.0ºC, dye concentration 3.0 %, dyeing assistant 40.0 g.L-1, dyeing time 3.0 hours, fixing agent 20.0 g.L-1, fixing time 10.0 minutes, volume ratio 1:20. Additionally, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) results indicated that reactive dyes were combined with maple fiber and diffused into the wood lumen and wood ray. X-ray diffraction (XRD) results indicated the intensive of crystallinity in the dyed wood was declined due to the dichlorotriazine reactive dye. Furthermore, thermogravimetric analysis (TGA) demonstrated that the residue of dyed veneer was higher than undyed, and the temperature at maximum degradation rate of dyed and undyed veneer was different.
The issue of behavior and deformation of joints of wooden structures is an integral part of the design of timber structures in its entirety. In this article the attention is therefore devoted to joints of timber structures. For testing there were selected joints with glued-in steel rods. These joints are currently, due to the frequent requirement for invisibility of joints in structures, at the forefront of interest. The content of this paper is therefore testing of these joints and determination of their carrying capacity and describing the type of deformation under load. These tests were carried out on a pressure machine EU100 in the laboratory of the Faculty of Civil Engineering VSB-TU Ostrava. The results of the laboratory tests have been statistically evaluated and accompanied by the graphical records of deformation response to loading. Comparison of test carrying capacity results with values determined from calculation according to the current applicable European standard for design of timber structures and numerical modeling are also presented.
This research investigates the prediction of modulus of elasticity (MOE) properties, which is the most important properties in many applications, of the oriented strand board (OSB) produced under different conditions (pressing time, pressing pressure, pressing temperature and adhesive ratios) by multiple regression, artificial neural network (ANN) and adaptive Neurofuzzy inference system (ANFIS). Software computing techniques are now being used instead of statistical methods. It was found that the constructed ANFIS exhibited a higher performance than multiple regression and ANN for predicting MOE.Software computing techniques are very useful for precision industrial applications and, also determining which method gives the highest accurate result.
This thesis deals with experimental verification of hot-air preservation efficiency on wooden members of structures against larvae of wood-destroying insects, particularly against larvae of longhorn beetle Hylotrupes bajulus L. The verification of hot-air efficiency on mortality of larvae was performed within the process of hot-air preservation of a room of a building in Čeladná, Czech Republic. Parameters of hot-air preservation met the specifications of standards according to which the process is controlled. The efficiency was monitored by means of the Acoustic Pack acoustic system which recorded acoustic emissions of larvae emitted during wood ingestion. To verify the acoustic system and hot-air preservation, the samples were subject to destruction analysis after the preservation. Using a Keyence VHX-S550E digital microscope, the analysis of changes in the structure of larvae before and after the process of preservation was performed. The results showed that designed parameters of hot-air preservation lead to the mortality of larvae.
This study presents the influence of retention reagents and multi-component retention systems on properties of pulp suspension which is used during toilet paper production. The following relationships were evaluated: influence of retention systems on rate of pulp suspension water drainage, values of specific cationic and anionic demand, Zeta potential of fibers, WRV values of fibers and water turbidity. The best results were achieved from applying three-component retention system which consisted of micro-milled bentonite Hydrocol OT, modified cationic polyethylenimin Polymín SK and cationic polyacrylamide Percol 830. The above mentioned three-component retention system resulted in increased rate of pulp suspension drainage by 43 %, improvement of water turbidity by 50 % and decrease of specific cationic demand by 33 %. The proposed retention system resulted in improved values of WRV pulp suspensions, which led to decrease of values by about 10 %. Influence of three-component retention system resulted only in minimal decrease of Zeta potential values for fibers.
Spoil heaps are negative urban landscape features resulting from intense human activities to acquire mineral resources. One very positive method for reclaiming spoil heaps is afforestation. This paper analyzes the quality of Black locust wood acquired from the reclaimed area of Varvažov, North Bohemian Basin, Czech Republic. The following characteristics were used as indicators of the quality of wood obtained from the given area: chip dimensions; ash content; bulk density; bark content; contents of C, H, N, and O; and contents of S, P, Ca, Mg, K, Fe, Zn, and Mn. Black locust biomass is suitable for energy purpose, although it contains an increased proportion of inorganic elements. The other properties, such content of C, H, N, and O, ash content as well as heating value, are in compliance with the standardized values. The Black locust chips can be categorized as Coarse-grained energetic wood chips with minimal dust particle content according to particle-size distribution analysis.
In this study, the surface quality of birch wood (Betula) test pieces planned with experimental planning tools (ET1, ET2) and influence of tool wear of quality of surface were examined. These tools were made by surfacing using a submerged arc welding (SAW) technique and a mixture of alloying elements (cromium, tungsten, fero-manganese, silicon carbide) spread on the surface under industrial flux. Surface roughness was measured along and across wood fibre. According to the results of experiments it is obviously that average roughness parameters along fibre is lower than across. Planning tool wear results revealed that 3200 m of cutting length is not significant for tools ET1 and ET2 wear. The same can be said about tool nose width change: For ET1 from 2.8 to 2.9 μm, and for ET2 from 2 to 3.4 μm – effect of negligible changes of tool edge geometry on planned surface quality is low. Feed of planning tool played more significant role – twice higher feed per insert (ET1 – 1.00 mm, ET2 – 0.5 mm) showed lower surface quality after planning. To reach necessary wood surface quality, lower feed rate and suggested experimental planning tool ET2 with higher wear resistance than commercial tool is preferable for planning of birch wood.
The objective of this study was to evaluate the effects of screw diameter, pilot hole diameter, screw type and loading rate on the withdrawal resistance of some screws in reconstituted bamboo lumber (RBL) and comparison of screw withdrawal resistance in RBL with MDF and Particleboard. Results indicate that there were no significant differences among withdrawal resistance with screw diameter, screw type and loading rate. Significant differences were found between withdrawal resistance with pilot hole diameter. Screw withdrawal resistance decreased with increasing pilot hole diameter. Suggested size of pilot hole is 60-85 % of the nominal screw diameter. The withdrawal resistances in the face and edge of RBL are greater than the end direction. This reveled RBL is anisotropic. Face and edge withdrawal resistances of screws in RBL were higher as compared with those of MDF and particleboard. This indicates that withdrawal resistance of RBL meets the requirements of furniture structure design.
The results of testing of chips extraction system efficiency during CNC milling of particleboards were presented in this paper. Experimental machining was performed using the 3-axis CNC router Weeke Venture 108M and a standard diamond tipped, newly sharpened shank-type router bit. As a material the market size (2200×1250×18 mm) laminated particleboards with density of 649 kg.m-3 were used. The efficiency of chips extracion system of the CNC machine depends on the mode of milling. For pocketing nearly 100 % of chips were removed succesfullywhile for through-milling it was only 87 %. The extraction system worked with very high effieiency regarding chips smaller than 0.1 mm. The chips extraction efficiency decreases for larger and havier chips.
In the current European standards for the design of timber structures, the issue of timberto-timber joint type is addressed only to squared timber, which makes the pinpointing of the round timber bolted joints carrying capacity near-unfeasible due to the insufficient support in the current standards. There have been made series of tests of round timber joints in different inclinations tensile load to the grainand also the reference tests of squared timber joints to compare the behaviour of this type of joints. Mechanical behaviour of round and squared timber bolted joints were tested in the laboratory of the Faculty of Civil Engineering in Ostrava.This paper presents results of static tests in tension at an angle of 0, 90 and 60° to the grain of squared and round timber bolted joints. Carrying capacity was determined according to the applicable standards and theories of fracture mechanics. Round timber joints were also numerically simulated. The test results of numerical models were then compared with the results of laboratory tests and theoretical calculations.
In order to improve people’s living quality and ameliorate their living environment, making the full use of the environmental characteristics of wood materials in the building and interior decoration become more and more important. In this paper, the development and application of eye tracking technology is summarized, and the development trend of eye movement research in the field of wood environment is reviewed. Through an eye tracking experiment research on indoor wood decoration space to explore if different specialty, the sex, the wooden interior proportion factor have significant effect on people’s judgment on the picture preference or not. Make exploration of people for different wood interior decoration environment preference and visual cognitive style, providing new ideas and methods for room decoration design. On the other side, through the study of the eye movement to explore the wood interior decoration environment has an objective and effective and scientific significance.
Comparative research was conducted on shear strength parallel to grain of heartwood of Scots pine (Pinus sylvestris L.) from the 16-18th century from Central Poland and of modern wood. Tests were performed on 150 samples of aged wood from 13 construction elements of 4 historic buildings and on 100 samples from 10 modern constructional elements. Aged wood revealed a better technical quality. The difference of average shear strength parallel to grain values equaled 0.09 MPa and the translation of correlation line was about 0.35 MPa in favour of aged wood.