Bending moment resistance of corner joints constructed with spline under diagonal tension and compression

We determined the effects of the penetration depth and spline material and composite material type as well as joining method on bending moment resistance under diagonal compression and tension in common wood panel structures. Composite materials were laminated medium density fiberboard (MDF) and particle board. Joining methods were buttand miter types. Spline materials were high density fiber board (HDF).The penetration depths of plywood, wood (Carpinus betolus) and splinewere 8, 11 and 14 mm. The results showed that in both diagonal compression and tension, MDF joints are stronger than particle board joints,and the bending moment resistance under compression is higher compared with that in tension. The highest bending moment resistance under tension was shown in MDF, butt joined using plywood spline with 8 mm penetration depth, whereas under compression bending moment resistance was seen in MDF, miter joined with the HDF spline of 14 mm penetration depth.     

人造板弯曲蠕变的变参对数模型

研究了中密度板、刨花板的弯曲蠕变,提出一种可以同时反映时间、载荷两因素的变参数对数模型,并应用Boltz-mann叠加原理对试样在变载荷下的弯曲蠕变进行了预测。结果表明。模型的理论值与实验值相吻合。     

Effects of density profile of MDF on stiffness and strength of nailed joints

Nail-head pull-through, lateral nail resistance, and single shear nailed joint tests were conducted on medium density fiberboard (MDF) with different density profiles, and the relations between the results of these tests and the density profiles of MDF were investigated. The maximum load of nail-head pull-through and the maximum load of nailed joints were little affected by the density profile. However, the ultimate strength of lateral nail resistance, the stiffness, and the yield strength of nailed joints were affected by the density profile of MDF and showed high values when the surface layer of the MDF had high density. It is known that bending performance is also influenced by density profile. Therefore, the stiffness and the yield strength of nailed joints were compared with the bending performance of MDF. The stiffness of nailed joints was positively correlated with the modulus of elasticity (MOE); in the case of CN65 nails, the initial stiffness of joints changed little in response to changes in MOE. The yield strength of nailed joints had a high positive correlation with the modulus of rupture (MOR). The stiffness and the yield strength of nailed joints showed linear relationships with MOE and MOR, respectively.     

Evaluation of particleboard deterioration under outdoor exposure using several different types of weathering intensity

The deterioration of particleboards for construction use was investigated by outdoor exposure tests at eight sites in Japan over 7 years. Two types of particleboard with different water resistances were tested and the deterioration of mechanical properties such as modulus of rupture, internal bond strength and lateral nail resistance was investigated. In order to eliminate regional differences in the board deterioration and also to standardize a deterioration factor for the board exposed to varying climate conditions, we introduced the weathering intensity (WI) defined by monthly precipitation multiplied by monthly average temperature. The significance of this factor was investigated by correlation analysis. Three conventional climate indexes relevant to the durability of wood were also investigated to analyze their significance to WI for particleboard deterioration. It was found that our definition of weathering intensity was the most accurate and the exposure period that reduces initial bending strength by half was calculated by the use of regression analysis for several different sites worldwide.     

The evaluation of long-term mechanical properties of wood-based panels by indoor exposure tests

Wood-based panels such as plywood, oriented strand board, particleboard, and medium-density fiberboard are used for roof, wall and floor sheathing materials in residential construction. However, the service life of these panels is still unknown due to the lack of long-term durability data. In this paper, test results from six different indoor exposure experiments were integrated to investigate the long-term durability of wood-based panels. The indoor exposure tests lasted for a maximum of 10 years, providing the panels with the changes in moisture content that ranged between 5 and 18%. The reduction in mechanical properties was determined to be in the range of 0–16% for the bending strength, 3–22% for the modulus of elasticity, 11–31% for the internal bond strength and 0–8% for the nail-head pull-through strength. No reduction was recognized for the lateral nail resistance. Furthermore, the concept of deterioration intensity (DI) based on the moisture content history was introduced to predict the long-term durability of the panels, and various calculation methods for DI were discussed so as to increase the correlativity of this property with the reduction in a mechanical property.     

模糊综合评判在板材气味评价中的应用

【目的】室内空气质量对人体健康影响巨大,家具板材是否环保至关重要。【方法】通过对板材气味综合评价,指导消费者对家具板材进行科学选取。以三聚氰胺贴面刨花板与中纤板及其素板为研究对象,用微池萃取仪采集气体,通过GC-MC-O嗅闻气味化合物种类及强度并分析其浓度,将模糊综合评判法应用于以上板材的气味评价。【结果】三聚氰胺贴面刨花板的模糊综合指数为2.885 0,各等级下的隶属度分别为0.208 7、0.225 6、0.207 4、0.188 6、0.169 7。刨花板素板的模糊综合指数为3.058 0,各等级下的隶属度为0.162 0、0.210 5、0.226 1、0.210 3、0.191 1。三聚氰胺贴面刨花板与三聚氰胺贴面中纤板气味评价等级为二级,质量良好,刨花板素板与中纤板素板气味评价等级为三级,质量合格。【结论】两种素板的模糊综合指数均偏高,其中含有危害性物质的释放,对板材进行贴面处理能够降低板材的危害性。本实验选用的中纤板的模糊综合指数稍高于刨花板。模糊综合评判法用科学的定量手段刻画板材气味评价中定性问题,使定性与定量分析融合。模糊综合评判在板材气味评价中考虑了多个气味化合物对板材的综合影响和各种气味化合物的毒性,它引导人们从另一角度客观评价板材质量,是一种可借鉴的好方法。     

Veneer strand flanged I-beam with MDF or particleboard as web material IV: Effect of web material types and flange density on the basic properties

The balance of strength between the flange and web parts of veneer strand flanged I-beam was investigated by the following methods: (1) use of different web material types, such as plywood, oriented strand board (OSB), particleboard (PB), and medium density fiberboard (MDF), that have different strength properties; and (2) fabrication of I-beams with low-density flanges using low-density strands with PB web material. Replacing PB or MDF with plywood showed slight significant improvement in the modulus of rupture but not in the modulus of elasticity of the entire I-beam. However, PB and MDF showed competent performance in comparison with OSB, thus strengthening the promising future of the use of PB or MDF as web material to fabricate I-beams. Hot-pressing conditions used for I-beam production exerted slightly adverse effects on the bending properties of PB, but not on MDF, OSB, and plywood web materials. The flange density of 0.60 g/cm³ was considered to be the lower limit that provides I-beams with balanced mechanical properties and dimensional stability.     

Utilization of sweet sorghum bagasse and citric acid for manufacturing of particleboard II: influences of pressing temperature and time on particleboard properties

Development of environmentally friendly particleboard made from sweet sorghum bagasse and citric acid has recently attracted attention. In this study, we investigated the effects of pressing temperature and time on physical properties, such as dry bending (DB), internal bond strength (IB), and thickness swelling (TS) of particleboard. Wet bending (WB), screw-holding power (SH), biological durability, and formaldehyde emission of particleboard manufactured under effective pressing temperature and time were also evaluated. Particleboards bonded with phenol formaldehyde (PF) resin and polymeric 4,4′-methylenediphenyl isocyanate (pMDI) were manufactured as references. Effective pressing temperature and time were 200?°C and 10 min, respectively. It was clarified that DB, IB, and TS satisfied the type 18 requirements of the JIS A 5908 (2003), and were comparable to those of particleboard bonded with PF and pMDI. The WB and SH of particleboard did not satisfy type 18 of JIS. Particleboard manufactured under effective pressing conditions had good biological durability and low formaldehyde emission. Based on the results of infrared spectra measurement, the degree of ester linkages increased with increased pressing temperature and time.     

Adhesive systems used in the European particleboard,MDF and OSB industries*

In this work, the adhesive systems used today in the European industries of particleboard, medium density fibreboard (MDF) and oriented strand board (OSB) are discussed. The structure of particleboard, MDF and OSB markets in Europe in relation to the types of adhesives and product specifications are presented as well. It is noticeable that new markets for wood-based panels like particleboard and fibreboard, known as non-furniture markets, are growing in Europe at a fast rate. It was concluded that most of the technological changes concerning the adhesive systems applied and additives have been realised from the need for niche panel products, the obligation to reach even lower formaldehyde emissions, and the necessity to decrease production costs due to the stringent competition in the market of wood-based panels.     

Fatigue in wood-based panels. Part 1: The strength variability and fatigue performance of OSB, chipboard and MDF

Wood-based panels used as floor decking can be exposed to fatigue as well as creep loading. The strength and fatigue performances of three wood-based panel products OSB, chipboard and MDF have been determined in four-point bending. The mean bending strengths were found to decrease in the following order MDF>OSB>chipboard. The bending strength variation within the OSB was considerably greater than that for chipboard and MDF. Normalised with respect to the static strengths, the fatigue performance of the chipboard was superior to that of the OSB, although the two materials have very similar performances at low stress levels. Normalised with respect to the static strengths, the fatigue performance of the MDF was inferior to both materials and at lower stress levels the fatigue performance deteriorated to a greater extent. However, in terms of absolute applied stress, the fatigue performance of the MDF was superior to that of the OSB, which was superior to that of the chipboard. However, as the stress was reduced the difference between the three materials reduced. At low stresses the performances of the three materials were quite similar. Received 5 August 1999     

我国人造板出口现状及目标市场形势分析

2011年我国人造板出5 245 911 541美元,品种包括胶合板、细木工板、刨花板、中密度纤维板等。笔者依据2007～2011年我国人造板出口贸易情况,分析了我国人造板出口所面临的机遇与挑战,提出了国拓展人造板国际市场的思路。     

秸秆刨花板性能分析

对普通木质刨花板、麦秸刨花板及稻草刨花板进行了密度、含水率、吸水厚度膨胀率、静曲强度和弹性模量、内结合强度、表面结合强度及握钉力的测试,结果表明,麦秸刨花板在强度方面不及木质刨花板,稻草刨花板在抗弯性能上也无法满足要求,两种秸秆板的握钉力都较差。产生上述差距的关键原因是板坯的密度,另外,与原料形态、加工工艺、机械设备等也有关系。     

Comparison of internal bond strength and compression shear strength of wood-based materials

The purpose of this study was to design a compression shear device for easy and fast measurement of the bonded shear strength of wood-based materials to replace the conventional method used to evaluate internal bond strength (IB). To assess the performance of this device, five differently sized specimens, included group I (dimension 5 × 1 cm), group II (5 × 2 cm), group III (5 × 3 cm), group IV (5 × 4 cm), and group V (5 × 5 cm) cut from commercial particleboard and medium-density fiberboard (MDF) (1.8 cm thick) were tested in compression shear. Only group V (5 × 5 cm) was prepared for the IB test. Results indicated that the compression shear strengths (CS) of particleboard and MDF, loaded in the horizontal or the diagonal direction, were greater than the IB, although a significant correlation existed between the two. This finding suggests that the IB of particleboard and MDF could be accurately estimated from the data collected by the CS test.Part of this report was presented at the Third Pacific Rim Bio-based Composites Symposium, Kyoto, December 2–5, 1996     

3种偶联剂对PVC木塑装板力学性能的影响

通过测试PVC基木塑装饰板的物理力学性能,研究3种偶联剂及偶联剂添加量对PVC木塑装饰板的抗弯强度、表面结合强度、板面握螺钉力和吸水厚度膨胀率的影响。结果表明：采用铝酸酯偶联剂PVC木塑装饰板的抗弯强度、表面结合强度、板面握螺钉力最大,72h吸水厚度膨胀率最小为0.47%;同时当铝酸酯添加量2%增加至6%时,PVC木塑装饰板的抗弯强度、表面结合强度、板面握螺钉力分别增加了7.9%、11.9%、10.8%72h吸水厚度膨胀率呈现先减后增趋势。     

Effect of element type on the internal bond quality of wood-based panels determined by three methods

Three mechanical tests with different loading modes were conducted to evaluate the effect of element type on the internal bond quality of wood-based panels. In addition to the internal bond test, which is commonly used for mat-formed panels, interlaminar and edgewise shear tests were used to test oriented strandboard (OSB), particleboard, medium-density fiberboard (MDF) of two thicknesses, and plywood. The following results were obtained. Epoxy resin proved to be suitable for determining the interlaminar shear modulus instead of hot-melt glue. There was a linear relation between panel density and interlaminar shear modulus and a linear correlation between the interlaminar shear strength and internal bond (IB) strength for the mat-formed panels tested. OSB had the highest edgewise shear modulus, and MDFs had the highest edgewise shear strength in this study. The modulus/strength ratio also depended on both panel type and loading mode. The relation between the shear moduli determined from the edgewise and interlaminar tests indicated the characteristics of the shear properties of panels made of different elements.Part of this paper was presented at the Fourth International Wood Science Symposium, Serpong, Indonesia, September 2002     

烟秆制备刨花板的力学性能研究

烟秆为烟草采摘烟口t-后的废弃物,为了更好的利用这种原料,利用不同含水率（9％、6％、3％、0％）和烟秆不同部位（上部、中部和下部）的刨花制成刨花板,测定刨花板的内结合强度、弹性模量和静曲强度,分析含水率和烟秆部位对刨花板力学性能的影响。结果表明,随着含水率从0增加至9％,刨花板的内结合强度从0．35MPa增加至0．58MPa,其弹性模量和静曲强度呈先增后减趋势,当含水率在6％时,烟秆刨花板的弹性模量和静曲强度最大。不同部位的烟秆刨花对刨花板的内结合强度、弹性模量、静曲强度有显著影响,其中,利用中部烟秆刨花制备的刨花板的内结合强度、弹性模量、静曲强度最小。利用烟秆刨花制备的刨花板其力学性能能达到国家标准的要求,因此利用烟秆制备刨花板是可行的。     

2005中国中密度纤维板工业综合调查

适应不同市场层次消费需求,中国中纤板工业经过约10年的强劲洗礼,产品结构日益完善,“丑小鸭”式起步的中国中纤板产品独领中国高端人造板市场风骚。特殊与创新的生产工艺决定了中纤板产品生产的特殊性,为年轻的中纤板市场开发打下了物质基础。经过10年的不懈努力与奋斗,2005给我们行业带来的是一个明媚的春天。     

Screw withdrawal capacity used in the eccentric joints of cabinet furniture connectors in particleboard and MDF

Eccentric joints are commonly used to join particleboard and medium-density fiberboard (MDF) in cabinet furniture construction. Screws and screws with plastic sockets are offered by many manufacturers for these kinds of joints, yet little information is available concerning their withdrawal capacity in these materials. Research reported here indicates that face withdrawal strengths of the screws differ slightly from manufacturer to manufacturer in particleboard and MDF, whereas withdrawal strengths of screws with plastic sockets differ greatly from one manufacturer to another. Furthermore, the withdrawal capacity of the screws was found to correlate with the density of both particleboard and MDF.     

Effect of board density on bending properties and dimensional stabilities of MDF-reinforced corrugated particleboard

We investigated the bending properties of composite boards produced by reinforcing both sides of corrugated particleboard with medium-density fiberboard (MDF). Thickness swelling and linear expansion (LE) were measured to assess the dimensional stabilities of the composite board. Although the apparent density of the composite board was 0.48g/cm³, its strength was found to be equivalent to that of 18-type particleboard as described in JIS A 5908. The boards parallel/perpendicular anisotropy in strength was 0.9. The modulus of rupture (MOR) of the composite board increased with board density only up to a certain density, beyond which the MOR was constant. On the other hand, the thickness swelling of both corrugated particleboard and the composite board was smaller than that of flat-type particleboard, satisfying the JIS A 5908 standard of 12%. Linear expansion (soaking in water of ordinary temperature for 24h) of corrugated particleboard was 0.7%–0.9% in the parallel direction and 2.1%–3.1% in the perpendicular direction; hence, anisotropy in linear expansion existed in the corrugated particleboard. The linear expansion of the composite board was 0.6%–0.9% in the parallel direction and 1.8%–2.5% in the perpendicular direction. Although the LE of the composite board was lower than that of corrugated particleboard, it is necessary to improve the LE of composite board for practical use.     

Deterioration of wood-based boards subjected to outdoor exposure in Tsukuba

Various types of wood-based boards were analyzed for deterioration after being exposed to an outdoor environment for 5 years in Tsukuba, Japan. In phenol–formaldehyde resin bonded particleboard (PB(PF)) and aspen oriented strand board (OSB(aspen)), longer exposure caused a greater reduction in the modulus of rupture and internal bond strength, an increase in the coefficients of variation, and a decrease in 95 % lower tolerance limit at the 75 % confidence level (95TL). Nail-head pull-through and lateral nail resistance were also reduced by outdoor exposure, but their coefficients of variation and 95TL were not significantly affected. In contrast, methylene diphenyl diisocyanate bonded medium density fiberboard (MDF(MDI)) only showed a slight deterioration of these properties even after 5-year exposure, and the coefficients of variation and 95TL hardly changed. After 5-year exposure, the retention of shear load in one-plane at relative displacement of 1.0 mm was high in MDF(MDI) and OSB(aspen) at 93.5 and 78.5 %, respectively, but low in PB(PF) at 41.1 %. As with PB(PF), OSB(aspen) also showed a sharp decrease in the modulus of rupture and internal bond strength, but only slightly reduced shear load in one-plane.