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.     

烟秆/木材刨花板的初步研究烟秆

初步探讨了实验室条件下烟秆/木材刨花板的生产工艺,研究了热压时间、施胶量、密度、木刨花加入量等因素对板材的静曲强度、内结合强度、吸水厚度膨胀率的影响.实验结果表明,烟秆/木材刨花板的静曲强度和吸水厚度膨胀率较纯烟秆刨花板有所提高,内结合强度相差不大.     

Effects of heat treatment on some properties of MDF (medium-density fiberboard)

This work investigated some mechanical, physical and free formaldehyde emission properties of heat-treated MDF. For this purpose, MDF panels were subjected to varying heat treatment temperatures (155°C, 165°C and 175°C), durations (2.5?h., 3.5?h. and 4.5?h.) and waiting times after hot pressing (30?min., 120?min. and 600?min). Thickness swelling (TS), water absorption (WA), free formaldehyde emission (FFE), bending strength (BS), modulus of elasticity (MOE), tensile strength perpendicular to fibers (TSPF) for treated and untreated samples were tested and evaluated statistically. Consequently, after the heat treatment values of tensile strength, bending strength and modulus of elasticity were almost negatively affected relatively, but the thickness swelling and water absorption and quantities of free formaldehyde were improved positively of MDF samples.     

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.     

Dimensional stability of MDF panels produced from fibres treated with maleated polypropylene wax

Medium-density fibreboard (MDF) was produced from fibres treated with maleated polypropylene wax. The objectives of this study were to improve the dimensional stability of MDF panels by this treatment; to observe the maleated polypropylene wax distribution within the MDF panels using conventional fluorescence microscopy; and to determine the effects of the treatment on the mechanical properties and vertical density profile of the panels. MDF panels were produced from two resin types (urea-formaldehyde and melamine-urea-formaldehyde) and three maleated polypropylene wax contents (0, 3 and 5%). Photomicrographs show that maleated polypropylene wax forms agglomerates within the MDF panels which is an evidence of its poor distribution in our experimental conditions. Our results show an important reduction on thickness swelling and water absorption after water soaking for panels produced from treated fibres. Linear expansion and contraction in adsorption and desorption conditions between 80 and 50% relative humidity increased following fibre treatment. However, thickness swelling and shrinkage in similar conditions showed an important reduction following fibre treatment. The fibre treatment did not have negative effects on the mechanical properties or the vertical density profile of MDF panels. The modulus of rupture and modulus of elasticity in bending were increased by the treatment independently of maleated polypropylene wax content. The internal bond strength increased following the addition of 5% maleated polypropylene wax content.     

表面型电磁屏蔽木基复合材料的制备及性能

选用镀镍布和粗化铜箔,制备具有电磁屏蔽功能的复合人造板。根据接合面的特点,分别选用聚醋酸乙烯乳液和环氧树脂,将镀镍布和粗化铜箔胶贴于人造板表面。性能检测结果表明,所制得的复合人造板的力学性能比人造板基材增强,镀镍布复合板的电磁屏蔽效能约60dB,铜箔复合板大于70dB,可满足屏蔽室建造用材的要求。     

磷酸三聚氰胺复配硼酸锌阻燃中密度纤维板的燃烧性能

选用磷酸三聚氰胺与硼酸锌复配,制备阻燃中密度纤维板(MDF),并采用锥形量热仪测试其燃烧性能,分析复配阻燃剂对板材燃烧性能的影响.结果表明:复配阻燃剂可有效提高MDF试材的阻燃抑烟性能,降低其热释放速率、总热释放量、产烟速率、总产烟量、CO及CO2生成速率,以磷酸三聚氰胺和硼酸锌等质量复配时,MDF试材的阻燃效果最优.     

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.     

The effect of hyperbranched polymer lubricant as a compatibilizer on the structure and properties of lignin/polypropylene composites

Abstract

In this work, the lignin/polypropylene (PP) composites were prepared by lignin and PP using hyperbranched polymer lubricant (HBPL) as a compatibilizer, which was synthesized by oleic acid and amino-terminated hyperbranch (HBP-NH₂) polymer in toluene solvent. The impact and flexural strength of the resulting composites were investigated. Experimental results indicated that the impact strength and flexural strength of lignin/PP composites modified with HBPL are 52.3% and 63.6% higher than that of untreated systems, respectively. HBPL treatment could also significantly improve the melt flow rate (MFR) of the lignin/PP composites. Meanwhile, the storage modulus (E′) of adding the HBPL was slightly higher than that of the uncompatibilized system. In addition, scanning electron microscope images showed that the dispersion of the lignin added with HBPL in the polymer matrix was improved. It can be inferred that the lignin and PP matrix interfacial bonding was strengthened.     

Development of high-performance UF-bonded reed and wheat straw medium-density fiberboard

Urea formaldehyde resin-bonded reed and wheat straw fiberboards were produced from the fibers made under different steam cooking conditions in refining processes at densities of 500 and 700kg/m³. The effect of steam cooking conditions on the board properties was examined. The steam pressure and cooking time for reed and wheat straws were 0.4MPa/10min and 0.4MPa/5min, respectively, and 0.6MPa/3min and 0.6MPa/10min for both straws. The effect of steam cooking treatment before the fiber refining process on the wettability and weight losses of the straws was also investigated. The results indicated that the mechanical properties and linear expansion of the straw medium-density fiberboard (MDF) were improved with increasing steam cooking pressure and time during the refining process, whereas the thickness swelling (TS) did not vary much. The wettability of the straws was improved by cooking treatment. The steam cooking conditions had little effect on the wettability of the straw surfaces. For reed and wheat straws, the weight losses increased with increasing steam pressure and cooking time. In addition, it was found that the properties of MDF were significantly higher than those of particleboard, especially the internal bond (IB), where the IB values of MDF were more than 10 times higher than those of particleboard. All the properties of the straw MDF, except the TS of wheat board, can meet the requirement of JIS fiberboard standard. The high performances of MDF could be due to the improved wettability and the removal of extractives during the refining process.     

The properties of flax fiber reinforced wood flour/high density polyethylene composites

Flax fiber(FF) was used to reinforce wood flour/high density polyethylene composites(WF/PE).WF/PE particles were uniformly mixed with FF via high-speed mixing and then extruded with a single screw extruder to prepare FF reinforced WF/PE composites(FF/WF/PE).Mechanical testing,dynamic mechanical analysis,scanning electron microscopy(SEM),creep measurement and Torque rheology were used to characterize the resulting composites.The results indicate that the mechanical performance of the composites could be remarkably improved by adding a limited amount of FF.The flexural strength and modulus increased by 14.6 and 51.4%,respectively(FF content of 9 wt%),while the unnotched impact strength could be increased by 26.5%(FF content of12 wt%).The creep resistance and toughness of thecomposite was markedly improved without changing the plastic content of the composite material.     

Reinforcement of fiberboard containing lingo-cellulose nanofiber made from wood fibers

Wood-based materials are fabricated with adhesives composed of various materials derived from fossil fuels. It is difficult to identify replacements for these chemical adhesives. This study explored nanofiber technologies as an alternative to these adhesives. In this study, we focused on reinforcement effects of lingo-cellulose nanofiber (LCNF) on fiberboards made from softwood and hardwood fiber. We discuss the density effects of reinforcement with LCNF because the density of medium-density fiberboard (MDF), which is widely used for construction, is standardized at about 0.60–0.80 g/cm³. Fiberboards were manufactured with three densities (0.60, 0.75, and 1.00 g/cm³). For softwood fiberboards, the bending properties for LCNF-mixed boards were higher than those for the control fiberboards at all densities. In this paper, control fiberboard means fiberboard with fiber only. For hardwood fiberboards, the bending properties for LCNF-mixed fiberboard for 1.00 g/cm³-density board were higher than those for the control fiberboard. For internal bond strength (IB), the IB for LCNF-mixed fiberboard was higher than that for the control fiberboard. The thickness swelling (TS) and weight change (WC) with water absorption for fiberboards containing LCNF were lower than those for control fiberboards. As a conclusion, physical and mechanical properties of the resulting fiberboards were significantly improved with the addition of LCNF, especially for softwood fiberboards, due to close binding between LCNF and wood fibers.     

Investigation of the effects of bark fiber as core material and its resin content on three-layer MDF performance by response surface methodology

The effects of using 100% black spruce (Picea mariana) bark fibers as core layer material accounting for up to 70% of the board and its resin content (between 6 and 10%) on the properties of three-layer medium-density fiberboard (MDF) were investigated using a full factorial experimental design with two independent variables and three levels. Five response variables, namely internal bond strength, modulus of rupture, modulus of elasticity, thickness swelling and water absorption were statistically analyzed using a response surface methodology and two-way analysis of variance. The effects of the proportion of core layer (bark fibers) and its resin content on panel properties were significant. All properties studied were positively affected by increasing core layer resin content. The effects of the proportion of core layer (bark fibers) on mechanical properties and water absorption were negative, but positive on thickness swelling. Simultaneous optimization of panel properties indicated that at a density of 850 kg/m³, a three-layer MDF with a core layer resin content of 6.5%, a face resin content of 12 and 60% of core layer proportion (spruce bark fibers) would satisfy the minimum requirements of ANSI standard for 130-grade MDF. Overall, black spruce bark, a major residue source in the Eastern Canada, should be considered as a supplemental furnish for the core layer materials of a three-layer MDF.     

竹醋液及竹醋液制剂对中密度纤维板防霉和贴面性能的影响

为拓宽竹醋液的用途以及提高中密度纤维板(MDF)的抗霉性,进行了竹醋液及竹醋液制剂抑菌性及对中密度纤维板防霉和贴面性能影响的研究,结果表明:①竹醋原液可以延长中密度纤维板霉变时间,且不影响中密度纤维板预油漆纸贴面强度;②PW1、PW2和PW3可以显著提高中密度纤维板防霉性能,但显著降低胶合强度;③PW4可以显著提高中密...     

相思、桉树刨花板两步法模压工艺的研究

以相思、桉树2树种的木材加工剩余物为原料,研究两步法刨花模压板的制造工艺以及各工艺参数与板材性能的关系.结果表明:以刨花预压制坯再进行热压模压的两步法刨花模压工艺,制备具有立体结构的刨花模压装饰板材的技术路线是可行的.相思和桉树2树种的对比试验研究结果表明:相思刨花模压制品性能优于桉树刨花模压制品.按选用工艺参数,相思原料的刨花模压制品性能完全达到相关国家标准.在工艺参数与板材性能相关性研究中,板材密度对模压板表观性能、内结合强度、静曲强度等板材性能具有显著性影响;热压模压温度和热压模压时间对板材吸水厚度膨胀率有较显著影响.施胶量增加,板材的各种物理力学性能都会提高,尤其对吸水厚度膨胀率影响最为显著.     

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.     

Cement-bonded particleboard with a mixture of wheat straw and poplar wood

We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard (CBPB) containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM (Response Surface Methodology). The mathematical model equations (second-order response functions) were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values (R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively). RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength > 12.5 MPa and internal bond strength > 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 (2003) for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.     

Effects of silane coupling agent level and extraction treatment on the properties of UF-bonded reed and wheat straw particleboards

Urea formaldehyde resin bonded reed and wheat particleboards with a density of 0.7g/cm³ were manufactured from two types of particle: fine and coarse particles. The effects of the silane coupling agent (SCA) level and ethanol-benzene (EB) treatment on the board properties were examined. For SCA, epoxide silane (SiEP) and amino silane (SiNH) were used for reed and wheat particles, respectively. The results are summarized as follows. (1) For both reed and wheat boards, the internal bond (IB) strength and thickness swelling (TS) were significantly improved at up to 5% SCA content, but the effectiveness of treatment kept constant at above 5%. (2) The level of SCA had little effect on the bending strength, especially for the boards composed of coarse particles. (3) EB treatment upgraded both the IB and TS of wheat board significantly. (4) SiEP incorporation improved the IB and TS of reed board significantly, whereas EB treatment was more effective for wheat board. (5) The dimensional stability of both reed and wheat boards under varying humidity could be improved by increasing the level of SCA and by EB treatment. EB treatment was more effective than SCA addition.     

Effect of thermo-mechanical refining on properties of MDF made from black spruce bark

The effects of thermo-mechanical refining conditions on the properties of medium density fiberboard (MDF) made from black spruce (Picea mariana) bark were evaluated. The bark chips were refined in the MDF pilot plant of Forintek Canada Corporation under nine different refining conditions in which preheating retention time was adjusted from 3 to 5 to 7 min and steam pressure was set at either 0.6, 0.9 or 1.2 MPa. The resulting bark fibers were blended with 12% UF resin (based on oven-dry fiber weight) using a mechanical blender. The resinated fibers were manually formed into fiber mats and hot-pressed into MDF panels using consistent parameters. Two panels for each refining condition were produced, resulting in a total of 18 panels. Analysis of variance (ANOVA) was used to analyze the significance of factors. Regression coefficients and 3D contour plots were used to quantify the relationship between panel properties and the two test factors. The results from this study indicated that the preheating retention time was a significant factor for both modulus of rupture (MOR) and modulus of elasticity (MOE), the steam pressure was a significant factor for internal bond strength (IB), MOR and MOE, whereas both factors were insignificant for thickness swelling, water absorption and linear expansion. The properties of MDF panels were quadratic functions of retention time and steam pressure. Compared to the ANSI standard for 120-grade MDF, most panels with a nominal density of 950 kg/m³ had very high IB (>1 MPa) and acceptable MOR, MOE and dimension stabilities. These results suggest that black spruce bark residues can be considered as a potentially suitable raw material for manufacturing MDF products.     

Effects of surface laminate type and recycled fiber content on properties of three-layer medium density fiberboard

ABSTRACT

High global production of medium-density fiberboard (MDF) in recent years could generate an equal quantity of waste MDF at the end of its service life, requiring recycling of waste MDF instead of landfilling or incineration. This study investigated effects of the addition of recycled fiber (RF) obtained from surface laminated MDFs with three different materials to the properties of three-layer recycled MDF (rMDF). Three types of surface laminates such as low-pressure laminate, polyethylene terephthalate, and polyester coating were hammer milled, and then went through a patent-pending fiber recovery system to obtain the resultant RFs that were added to the core layer of rMDF. These RFs at three contents (10, 20, and 30%) were blended with 12% of urea-formaldehyde (UF) resin prior to hot-pressing. Statistical analysis showed that the best internal bonding strength, modulus of rupture, and modulus of elasticity of rMDF panels were obtained for LPL-rMDF with a 20% RF content. Thickness swelling, water absorption, and formaldehyde emission of rMDF were reduced by increasing the RF content. These findings suggest that a minimum RF content of 20% can be replaced with virgin fibers for the rMDF manufacture, indicating the feasibility of recycling waste laminated MDF into three-layer rMDF.