Assessment of temperature and relative humidity conditioning performances of interior decoration materials in the Taipei area (II)

The purpose of this study was to explore the conditioning effects of wood panels (used as interior decorating materials). We examined hourly the temperature and relative humidity (RH) in a living environment based on the average values during winters from 1974 to 1990 in the Taipei area. Thirty-six interior finish materials attached to one inside surface of a 35cm³ simulation aluminum container were used in this study. An A/V value (surface area of interior decoration materials attached to container/inside volume of container) of 2.86m^–1 or various other A/V values and panel thicknesses had no significant effect on the room temperature changing ratio. The hygroscopic conditioning performances of these decorative materials were classified into four types in accordance withb values: type I (b>0.0200) included four solid woods (unfinished), two wood-based materials, three composite materials, and one inorganic material. Type II (0.0170<b<0.0199) included one solid wood, eight wood-based materials, and two inorganic materials. Type III (0.0070<b<0.0169) included 11 wood-based materials and four inorganic materials. The RH changing ratio decreased curvilinearly with increasing interior decorating panel thickness and A/V values in a sealed container, whereasb values increased with increasing interior decorating panel thickness and A/V values in a sealed container.Part of this report was presented at ICEUPT'99, Chi-Tou, Taiwan, ROC, May 21–23, 1999     

Thermal insulation properties of wood-based sandwich panel for use as structural insulated walls and floors

Thermal insulation and warmth-keeping properties of thick plywood-faced sandwich panels with low-density fiberboard (plywood-faced sandwich, PSW), which were developed as wood-based structural insulation materials for walls and floors, are comprehensively clarified. The properties focused on were thermal conductivity (λ), thermal resistance (R), and thermal diffusivity (D). The results for PSW panels were compared with those for commercial wood-based boards, solid wood, and commercial insulators. The λ values were measured for PSW panels and their core and face elements. As a result, the composite theory of λ was found to be appropriate for PSW composites, because the calculated/experimental λ ratios were approximately 90%. The λ values for PSW panels with densities of 340 kg/m³ (PSW350) and 410kg/m³ (PSW400) were 0.070 and 0.077W/mK, respectively. The R values for PSW350 and PSW400 were 1.4 and 1.2m²K/W, and the D values were 0.00050 and 0.00046m²/h, respectively. Consequently, the PSW provided thermal insulation properties superior to those of the boards and in terms of warmth-keeping properties were greatly advantageous over the insulators. These advantages were due to the moderate densities of PSW panels. The PSW panel with sufficient thickness showed remarkably improved thermal resistance compared with those of the boards.     

Elastic moduli and stiffness optimization in four-point bending of wood-based sandwich panel for use as structural insulated walls and floors

Several wood-based sandwich panels with low-density fiberboard core were developed for structural insulated walls and floors, with different face material, panel thickness, and core density. The elastic moduli with and without shear effect (E _L, E ₀) and shear modulus (G_b) were evaluated in four-point bending. Generally, the stiffer face, thicker panel, and higher core density were advantageous in flexural and shear rigidity for structural use, but the weight control was critical for insulation. Therefore, optimum designs of some virtual sandwich structures were analyzed for bending stiffness in relation to weight for fixed core densities, considering the manufactured-panel designs. As a result, the plywood-faced sandwich panel with a panel thickness of 95 mm (PSW-T100), with insulation performance that had been previously confirmed, was most advantageous at a panel density of 430 kg/m³, showing the highest flexural rigidity (E _L I = 13 × 10⁻⁶ GNm²) among these panels, where E _L, E ₀, and G _b were 3.5, 5.5, and 0.038 GN/m², respectively. The panel was found to be closest to the optimum design, which meant that its core and face thickness were optimum for stiffness with minimum density. The panel also provided enough internal bond strength and an excellent dimensional stability. The panel was the most feasible for structural insulation use with the weight-saving structure.     

Effects of fire-retardant treatment and wood grain on three-dimensional changes of sandwich panels made from bubinga decorative veneer

ABSTRACT

The effects of a fire-retardant treatment (FRT) and wood grain on three-dimensional changes of aircraft sandwich panels were evaluated. Unvarnished and varnished panels having the outer decorative layer made with bubinga (Guibourtia spp.) were studied. Half of the samples from each type of panel received an FRT (phosphate-based) on all three layers of the decorative plywood. The other half had the two inner layers treated and the outer layer untreated. Three different figures formed by the rotary cutting and grain orientation were identified and separately studied on veneer surfaces. Samples pre-conditioned to 20°C and 40% relative humidity (RH) underwent an adsorption (25°C, 90% RH) and then a desorption (25°C, 40% RH) treatments. Changes in moisture content (MC), swelling, shrinkage, roughness, and waviness were measured after each moisture exposure condition. The results showed that the FRT increased significantly MC, swelling, and shrinkage of unvarnished and varnished panels. This treatment as well as the type of wood figure affected roughness and waviness variations of unvarnished panels. However, the effects of these two factors were not noticeable once panels were varnished.     

Feasibility of supercritical carbon dioxide as a carrier solvent for preservative treatment of wood-based composites

 Supercritical carbon dioxide (SC-CO₂) was tested for its potential as a carrier solvent for preservative treatment of solid wood and wood-based composites. A preliminary trial showed that the treatability of solid wood varied with its original permeability and that the SC-CO₂ treatment was not promising for refractory timber species such a Larix leptolepis Gordon. In contrast, 3-iodo-2-propynyl butylcarbamate (IPBC)/SC-CO₂ treatment resulted in enhanced decay resistance without any detrimental physical or cosmetic damage in all structural-use wood-based composites tested: medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board (OSB). Further trials under various treatment conditions [25°C/7.85 MPa (80 kgf/cm²), 35°C/7.85 MPa, 45°C/7.85 MPa, 35°C/11.77 MPa (120 kgf/cm²), and 45°C/11.77 MPa] indicated that although small changes in the weight and thickness of the treated materials were noted the strength properties were not adversely affected, except for a few cases of softwood plywood and oriented strand board. The results of this study clearly indicated that the treatment condition allowed SC-CO₂ to transport IPBC into wood-based composites, and the optimum treatment condition seemed to vary with the type of wood-based composite. Received: October 24, 2001 / Accepted: February 15, 2002 Part of this work was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001; and the 32nd Annual Meeting of the International Research Group on Wood Preservation, Nara, May 2001 Correspondence to:M. Muin     

Twelve elastic constants of Betula platyphylla Suk

Wood elastic constants are needed to describe the elastic behaviors of wood and be taken as an important design parameter for wood-based composite materials and structural materials. This paper clarified the relationships between compliance coefficients and engineering elastic constants combined with orthotropic properties of wood, and twelve elastic constants of Betula platyphylla Suk. were measured by electrical strain gauges. Spreading the adhesive quantity cannot be excessive or too little when the strain flakes were glued. If excessive, the glue layer was too thick which would influence the strain flakes’ performance, and if too little, glues plastered were not firm, which could not accurately transmit the strain. Wood as an orthotropic material, its modulus of elasticity and poisson’s ratios are related by two formulas: μ ij/Ei=μji/Ej and μ ij<(Ei/Ej)1/2. The results showed that the elastic constants of Betula platyphylla Suk. measured by electrical strain gauges were accurate and reliable. The results of shear elastic modulus G _TL and G _LR show a high linear regression correlation coefficient (>0.95) between the reciprocal of elastic modulus MOE ⁻¹ and the square of the ratio of depth to length (h/l)², which indicate that shear modulus values measured were reliable by three point bending experiment.     

木质室内装饰材料的环境湿度调节功能Ⅲ

本研究测定了在水蒸汽流入流出过程中壁纸、椴木三合板、柞木地板块、两面光ＭＤＦ这４种室内装饰材料的环境湿度调节参数ｘ和ｙ与气积比Ａ／Ｖ、试材初含水率及环境温度之间的关系曲线。在此基础上,得到了在水蒸汽流出条件下室内装饰环境的湿度设计诺谟图,为科学、全面地进行居住空间的湿度设计奠定了理论基础。     

The lamination influence on properties of agro-based particleboard

Abstract

Response surface methodology (RSM) based on a three-level, three-variable central composite rotatable design was applied to evaluate the effects of the parameters such as ratio of rice straw (Oryza sativa)/poplar (Populus deltoids) wood particle bonded with urea-formaldehyde resin in panels, species of wood veneer coating these panels and amount of adhesive in glue line on the modulus of rupture (MOR), internal bonding (IB), and thickness swelling (TS) of panels. Mathematical model equations were derived by computer simulation programming to optimize the properties of the particleboard. These equations that are second-order response functions representing MOR, IB, and TS were expressed as functions of three operating parameters of panel properties. Predicted values were found to be in a good agreement with experimental values (R ² values of 0.96, 0.98 and 0.98 for MOR, IB, and TS, respectively). This study has shown that the RSM could efficiently be applied for modeling panel properties. It was found that the variables affected the properties of panels. Straw usage up to 30% in the mixture did not cause a significant decrease in MOR, IB, and TS. Using beech veneer and 190 g/m² glue line had the highest MOR and lowest TS.     

Regional employment trends of wood-based industries in Germany’s forest cluster: a comparative shift-share analysis of post-reunification development

After reunification in 1990, Germany’s forest cluster developed anew and employment in the wood-based industries differentiated very quickly. With more than 900,000 employees, it is now considered one of the most important industrial sectors in the country. This paper analysed general trends in the development of employment of wood-based industries in the German forest cluster between 1999 and 2006. Shift-share analysis was considered to be the most appropriate way to determine regional differences in the subsection DD/20 ‘Manufacture of wood and wood products’ of the code “Classification of Economic Activities in the European Community, Revision 1.1” (NACE): the sawmill industry, the wood-based panel industry, the wood construction industry, the wood-based packaging industry, and the miscellaneous wood products industry. This method decomposed the change of employment into three different components that are due to that change: national trends, (industrial) sectoral trends, and regional conditions. Employment in the selected wood-based industries showed a significantly larger decrease than overall trends in both the producing industries and the whole economy of Germany: a continual loss of employees could be observed over the time period, affecting almost all of the selected wood-based industries. However, federal states in western and eastern Germany experienced divergent trends between 1999 and 2006, as different absolute and relative regional share components indicated in the shift-share analysis. This method allows of identifying regional disparities and characterising regions with positive (mainly eastern federal states) and negative (mainly western federal states) rates of employment growth. The research suggests that positive employment trends in eastern Germany’s wood-based industries can mainly be attributed to regional factors such as comparatively higher subsidies for new investments, lower labour costs, lower land values or infrastructural peculiarities.

Assessment of hygroscopic conditioning performance of interior decorative materials IV: Sorption characteristics of wood under high relative humidity condition

The equilibrium moisture content (EMC) of six wood species under desorption conditions of 20°C and 100% 0% relative humidity (RH), and the rate of adsorption at various depths of three wood species blocks under 98% RH at 22.5°C were studied. There were no significant differences among the EMC values for these six wood species over the RH range 40% 0%, but there were highly significant differences over the RH range 100% 50% at constant 20°C. The amount of moisture absorbed in the wood decreased curvilinearly with the increase of depth in the specimens as sorption time increased, and their relation could be represented by a semilogarithmic equation. Time-dependent adsorption behavior at various depths of the wood specimens could be represented by an exponential equation as a function of the product of the difference between moisture contents at equilibrium and initial conditions and the term (1 – e^–t/). The value of of various wood species was found to increase linearly with the increased depth of the specimen and showed the following trend: hard maple (Acer sp.) > China fir (Cunninghamia lanceolata) > Japanese cedar (Cryptomeria japonica D. Don).Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997.     

Colorimetry of wood specimens from French Guiana

The color of 97 species of wood specimens from French Guiana was measured on their radial and tangential surfaces with a colorimeter. We obtained the tristimulus values of X, Y, and Z of the 10° standard observer under the illuminant of D ₆₅, and the values of the CIELAB color system, L ^*, a^*, b^*, C^*, and h. When the lightness index (L ^*) was <54, b ^*, C ^*, and h showed positive correlations against L ^*. When L ^* was >54, a ^* and C ^* showed negative correlations against L ^*. These results imply that wood color should be discussed by separating wood specimens into the high and low-lightness groups. A good positive correlation was found between the L ^* and h throughout the whole range of L ^*. It is thought that the value of h can be an important index, as can L ^*, for comparing of wood color because h shows a simple relation with L ^*.     

Kiln drying behavior of lumber from ten fast-growth plantation species in Costa Rica

Abstract

Plantation wood from tropical climate has been introduced rapidly in the national market; however, there is lack of knowledge about the process. The main objective of this study was to investigate the kiln drying behavior of 10 plantation-grown wood species from natural forest in Costa Rica using the recommended drying schedule. Initial moisture content (MCi), final moisture content (MCf), drying rate, drying time, and drying defects were evaluated. The drying schedule applied produced the following results: (1) high MCi (over 110%) in four species and lower values in two species. (2) The largest drying time was found in species with high MCi, and the shortest drying time in species with lower MCi. (3) Significant variations of target MCf were found in some species, despite equalization and conditioning. (4) Exponential relationship MC=a*?^?t*b was used to establish a moisture content (MC) decrease model, which is not a good indicator of drying time for fives species. (5) High incidence of drying defects was found in Alnus acuminata and Vochysia guatemalensis. According to the above results, it is necessary to test other drying schedule oriented to improve lumber quality and to decrease variability of MC in wood from plantation trees.     

Theoretical computation and analysis of benefits of wood cutting power

This paper studies the problem of high energy waste in the course of the wood fiber processing in the wood-based panel industry. In the light of the energy economy principle, the cutting theory on the micron and long-slice wood fiber was put forward. In this paper, by means of analyzing the power waste in traditional processing, a series of analytical measures, such as, cytology, super precision work theory and fiber processing, and so on were utilized in the micron wood fiber formation process, and the cutting conception of the micron and long-slice wood fiber was put forward. Accordingly, the study of the micron and long-slice wood fiber was put into the microstructure study. This paper scientifically explains the reasons why the traditional wood fiber processing consumes more energy and the fiber quality low. In an example, the cutting power on the micron and long-slice wood fiber was calculated, which was compared with the traditional cutting power. The result showed that the energy waste by machining at micron is much lower than by heat grind and the high quality and long-slice wood fiber was gained. Thus, a revolutionary step was taken in the paper-making and wood-based panel industry of China. __________ Translated from Scientia Silvae Sinicae, 2006, 42(3): 44–46 [译自: 林业科学 2006, 42(3): 44–46]     

Heat-induced colour changes of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood

Heat treatment of Pinus pinaster and Eucalyptus globulus wood was carried out by hot air in an oven for 2–24 h at 170–200°C and by steam in an autoclave for 2–12 h at 190–210°C. The colour parameters L*, a* and b* were determined by the CIELAB method on radial, tangential and transverse sections of untreated and treated wood, and their variation with regard to the treatment (ΔL*, Δa* and Δb*) were calculated in percent. For untreated eucalypt wood, lightness (L*) varied between 54.1 and 63.8% with a* between 7.4 and 8.5, and b* between 15.7 and 19.9. For untreated pine wood, L* varied between 67.3 and 76.1%, a* between 6.9 and 7.6 and b* between 16.3 and 24.1. Oven heat-treated wood became darker (ΔL* about 50% for 4% mass loss), and this was more for eucalypt wood under the same treatment conditions. In general, the contribution of red (a*) and yellow (b*) colour decreased with heat treatment. The transverse section of the two species darkened less for both the treatments with small differences between radial and tangential sections. Lightness decrease was related to chemical changes; with good correlations with glucose (R ² = 0.96), hemicelluloses (R ² = 0.92) and lignin (R ² = 0.86). As regards colour, the heat treatments showed an interesting potential to improve the wood quality for solid timber products from pine and eucalypt.     

Difference in mass concentration of airborne dust during circular sawing of five wood-based materials

The object of this study was to compare the mass concentration of airborne dust during circular sawing of five wood-based materials: solid sugi (Cryptomeria japonica) lumber, tropical hardwood plywood, softwood plywood, particleboard, and medium-density fiberboard. Specimens were sawn at a constant feed per tooth (0.05 mm) using two saw speeds. The mass concentration of airborne dust of diameter 7.07 μm or less (respirable dust) was measured with a light-scattering dust monitor. The mass concentration showed a log-normal distribution, and the geometric means of mass concentration at saw speeds of 2000 and 3000 rpm were 2.33 and 2.89 mg/m³ for tropical hardwood plywood, 1.13 and 2.84 mg/m³ for particleboard, 0.91 and 2.28 mg/m³ for medium-density fiberboard, 1.09 and 1.38 mg/m³ for softwood plywood, and 0.32 and 0.66 mg/m³ for sugi lumber. The mass concentration for all five wood-based materials increased with the revolution speed of the circular saw.     

The amount of wooden material in a closed room and its effect on the reverberation time

Optimal sound-absorbing materials are vital for desirable room acoustics. The effect of wood used for interior wall decoration on the acoustical environment is explored in a controlled room by changing the amount of wall wooden materials. The effect on the interior reverberation time (RT) is reported in this work. The experiment was conducted in a relatively small concrete brick house (approximate dimensions 4.6 × 3.2 × 4.2 m). Results showed that room shape and the arrangement of wooden wall decoration materials were important factors affecting the RT at different receiving positions. As the amount of wall decorating wood materials increased, the interior RT in the house decreased linearly; however, the RT at low frequencies diverged. After the analysis of covariance, all frequency variables were adjusted to the same level and a general regressive formula was developed as RT = C − 0.005 DR. Where RT is the reverberation time (s), DR is the amount of interior wood materials used (%), and the C values were constants that ranged from 0.888 to 1.606 and varied according to the different octave bands. Furthermore, it was found that the increasing influential effect with the DR showed diminishing marginal utility. This means that the influence of DR on RT was not linear, and, therefore, the marginal utility should be considered in order to use wooden panels economically. Part of this report was presented at 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003     

Characterization of wood-based molding bonded with citric acid

The wood-based moldings were fabricated by using only citric acid as an adhesive. The mechanical properties, water resistances, thermal properties and chemical structure were investigated. Wood powder obtained from Acacia mangium was mixed with citric acid under certain weight ratios (0–40 wt%), and each powder mixture was molded using two types of metal molds at 200°C and 4 MPa for 10 min. The modulus of rupture and the modulus of elasticity values of the wood-based molding containing 20 wt% citric acid were 35.8 MPa and 5.4 GPa, respectively. The maximum impact strength was 0.94 kJ/m² with the same citric acid content. The water resistance increased with increasing citric acid content, and the good resistance to boiling water was also recognized. However, some elution of substances derived from citric acid was observed at high levels of citric acid, causing a decrease in the thermal properties. The ester linkages were detected by Fourier transform infrared spectroscopy, indicating that the citric acid reacted with the wood. Our results demonstrated that citric acid brought about good adhesiveness for fabricating the wood-based molding.     

Influence of moisture content on the vibrational properties of hematoxylin-impregnated wood

The vibrational property of hematoxylinimpregnated wood was investigated from the aspect of moisture content dependence. The specific dynamic Young's modulus (E/) and loss tangent (tan) of hematoxylin-impregnated wood were determined in the relative humidity (RH) range of 0%–97%, and were compared with those of the untreated and some conventional chemically treated woods. The changes in theE/ and tan of wood with increasing RH were suppressed by acetylation and formaldehyde treatment because of a marked reduction in the hygroscopicity of the wood. Although the hematoxylin impregnation did not significantly affect the hygroscopicity of the wood, its influence onE/ and tan were similar to that of formaldehyde treatment at low RH and of acetylation at medium RH. It was supposed that at low to medium RH hematoxylin restrains the molecular motion of amorphous substances in the cell wall because of its bulkiness and rigidity. On the other hand, at high RH it seems to work as a plasticizer with adsorbed water molecules.     

Utilization of pine (Pinus pinea L.) cone in manufacture of wood based composite

Physical and mechanical properties of medium density fiberboards (MDF) made from various mixtures of wood fibers and stone pine (Pinus pinea L.) cones were evaluated using European standards. MDF panels were manufactured using standardized procedures that simulated industrial production at the laboratory. Six panel types were made from mixtures of wood fiber/cone flour, 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 percents, respectively. Addition of the cone flour into the MDF significantly reduced formaldehyde emission from the panel. In addition, the addition of 10% cone flour also improved water resistance of the MDF panels made using urea–formaldehyde (UF) resin. However, further addition of the cone flour into the panel negatively influenced their water resistance. Flexural properties and internal bond strength decreased with the increase of cone flour content in the panel. The UF resin is the main source of formaldehyde emission from the UF-bonded wood-based panels. Depending on addition of the cone flour in the panels, the formaldehyde emission values ranged from 2.6% to 55.3% lower than the panels made from 100% wood fiber. Based on the findings obtained from this study, pine cone can be used as a renewable biological formaldehyde catcher as an alternative to the traditional formaldehyde catchers for E1 Class MDF manufacture.     

Preservative properties of vapor-boron-treated wood and wood-based composites

The treatability of wood (sapwood ofCryptomeria japonica D. Don) and wood-based composites (particleboard, waferboard, medium-density fiberboard, plywood) with vapor-boron was good, and the treated materials proved to be resistant to decay fungi and subterranean termites in laboratory bioassays. No difference in effectiveness was noted between vapor-boron and liquid-boron treatment of wood. Toxic threshold values determined for solid wood were 0%–0.24%, 0.26%–0.51%, and 0.26%–0.51% BAE (boric acid equivalent), respectively, against the white-rot fungusTrametes versicolor (L.: Fr.) Pilat, the brown-rot fungusFomitopsis palustris (Berk. et Curt.), and the subterranean termiteCoptotermes formosanus Shiraki. A concentration of less than 1% BAE seemed sufficient to control biological attacks on composites, although the toxic limits could not be determined more accurately because of the tested range of boron retention. High boron retention was needed to meet the performance requirements for slow-burning materials when a fire-retardant agent was not incorporated into the glue line.