Evaluation of mechanical and physical properties of industrial particleboard bonded with a corn flour–urea formaldehyde adhesive

The aim of this study was to determine the effect of corn flour content of urea formaldehyde (UF) resin on the panel properties of particleboard. Corn flour was added to UF resin to decrease the free formaldehyde content of particleboard panels. Some physical (thickness swelling and rheological characterization), mechanical (modulus of elasticity, modulus of rupture, internal bond strength and withdrawal of screws) properties and formaldehyde emission of particleboards were evaluated. The results showed that the introduction of small proportions of corn flour (7%, by weight) in UF resins contributes to the improvement of mechanical and physical properties of the boards and reduced their formaldehyde emissions. Hazardous petrochemical UF could be partially substituted in industrial applications by addition of corn flour. To our knowledge, this is the first study on this kind of wood adhesives.     

Using almond (Prunus amygdalus L.) shell as a bio-waste resource in wood based composite

In this research, the suitability of almond shell as a bio-waste resource in wood based composite manufacturing was investigated. Particleboards containing different almond shell particle rations were made using urea–formaldehyde (UF) resin. Some chemical properties of almond shell (holocellulose, α cellulose, lignin and ash contents, alcohol–benzene solubility, 1% NaOH solubility, hot and cold water solubility), mechanical (modulus of rupture, modulus of elasticity and internal bond strength) and physical properties (thickness swelling and water absorption) of the particleboards were determined. The addition of almond shell particles greatly improved the water resistance of the panels. However, flexural properties and internal bond strength decreased with increasing almond shell particle content. The amount of almond shell particles at most should be 30% in the mixture to meet the standard required for mechanical properties. Conclusively, almond shell, an annual agricultural residue, could be utilized with mixture of wood particles in the particleboard manufacturing.     

The influence of moisture content of raw material on the physical and mechanical properties,surface roughness,wettability, and formaldehyde emission of particleboard composite

The objectives of this research were to investigate surface characteristics, physical (thickness swelling) and mechanical (modulus of rupture, modulus of elasticity and internal bond strength) properties, and formaldehyde emission of particleboard composite, as affected by moisture content of wood. Three-layered particleboard panels manufactured from wood particles at five different moisture contents (20%, 40%, 60%, 80% and 95%). Roughness measurements, average roughness (R_a), mean peak-to-valley height (R_z), and maximum roughness (R_y), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. Contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Statistical analysis showed significant differences in the surface roughness, contact angle, formaldehyde emission, physical and mechanical properties of the panels following moisture content. Based on the findings obtained from this study, an increase or decrease in the moisture content of wood beyond a certain limit, before chipping operations, negatively affected the wettability and smoothness of particles, and formaldehyde emission, physical and mechanical properties of particleboards.     

Effects of anatomical and chemical properties of wood on the quality of particleboard

The objective of this study was to investigate the effects of anatomical and chemical structures of wood on the quality properties of particleboard containing different mixture of wood species. Urea–formaldehyde adhesive was used as a binder for manufacturing of test panels. Anatomical and chemical properties of wood species, and physical and mechanical properties particleboards were evaluated. The anatomical and chemical structures were found to be effective on the all of the properties of particleboards. Panels made from the particles including more amount of pine wood had highest mechanical strength properties and lowest thickness swelling values. Cellulose, hemicellulose and lignin contents, acidity and solubility values (in hot–cold water, dilute alkali and alcohol benzene) of wood significantly affected all of the properties of particleboards. The physical and mechanical properties of particleboards showed statistically differences related to the length, thickness and number of the cells and fibers.     

Improving core bond strength and dimensional stability of particleboard using polymer powder in core layer

Low density polyethylene powder (LDPE) was used as polymer binder in the core layer of three layer particleboard. In the first phase, six levels of the LDPE powder (5–30 wt.%) based on the composition by weight, were mixed with the core particles with 8 wt.% urea–formaldehyde (UF) resin. In the second phase, the LDPE powder content was kept constant at 10 wt.% in all treatments and the UF resin content applied to the core layer was decreased gradually from 8 to 4 wt.%. Thickness swelling and water absorption of the particleboards significantly decreased with increasing the LDPE content in the core layer. Similarly, incorporation of the LDPE powder into the core layer of the particleboard greatly improved internal bond strength. The flexural properties of the particleboards, the modulus of rupture (MOR) and modulus of elasticity (MOE), were positively affected by increasing LDPE content up to 10 wt.% but the further increment of the LDPE decreased the MOR and MOE. The UF resin content can be reduced in the core layer of the particleboard as a function of increasing the LDPE powder.     

The potential for using walnut (Juglans regia L.) shell as a raw material for wood-based particleboard manufacturing

In this study, the suitability of walnut shell as a renewable agricultural residue for panel manufacturing was investigated. Particleboards containing different walnut shell particle ratios (0%, 10%, 20%, 30%, 40% and 100%) were made using urea–formaldehyde (UF) resin. Some chemical properties of walnut shell (holocellulose, α cellulose, lignin and ash contents, alcohol–benzene solubility, 1% NaOH solubility, hot and cold water solubility), mechanical (modulus of rupture, modulus of elasticity and internal bond strength) and physical properties (thickness swelling and water absorption) of the particleboard were determined. The addition of walnut shell particles greatly improved the water resistance of the panels. However, flexural properties and internal bond strength decreased with increasing walnut shell particle content. The results indicated that panels can be manufactured utilizing walnut shell particles up to 20% without falling below the minimum EN Standard requirements of mechanical properties for general purpose use. Conclusively, walnut shell, an annual residue, could be utilized with mixture of wood particles in the manufacture of particleboard used for outdoor environments due to lower thickness swelling and water absorption.     

The potential for using walnut (Juglans regia L.) shell as a raw material for wood-based particleboard manufacturing

In this study, the suitability of walnut shell as a renewable agricultural residue for panel manufacturing was investigated. Particleboards containing different walnut shell particle ratios (0%, 10%, 20%, 30%, 40% and 100%) were made using urea–formaldehyde (UF) resin. Some chemical properties of walnut shell (holocellulose, α cellulose, lignin and ash contents, alcohol–benzene solubility, 1% NaOH solubility, hot and cold water solubility), mechanical (modulus of rupture, modulus of elasticity and internal bond strength) and physical properties (thickness swelling and water absorption) of the particleboard were determined. The addition of walnut shell particles greatly improved the water resistance of the panels. However, flexural properties and internal bond strength decreased with increasing walnut shell particle content. The results indicated that panels can be manufactured utilizing walnut shell particles up to 20% without falling below the minimum EN Standard requirements of mechanical properties for general purpose use. Conclusively, walnut shell, an annual residue, could be utilized with mixture of wood particles in the manufacture of particleboard used for outdoor environments due to lower thickness swelling and water absorption.     

Formulation and process modeling of particleboard production using hardwood saw mill wastes using experimental design

Hardwood saw mill residues have traditionally not been favoured by the particleboard industry owing to their high density and extractive contents. The work presented here deals with investigating the use of hardwood saw mill residues, which are currently treated as solid wastes, in producing industry-grade particleboard.

The formulation and process modeling of particleboard production using hardwood sawmill wastes has been studied by employing experimental design and response surface method. The optimum settings found on resultant boards, were further investigated considering physical and mechanical properties of the board as well as economical considerations. It was found that industry grade hardwood particleboards can be produced in the laboratory with practical processing parameters (surface moisture, core moisture, resin load for the surface, resin load for the core, hardener content for the core, pressing time and press temperature). Formulation and validation of stochastic models for modulus of rupture (MOR) and modulus of elasticity (MOE) are presented in this paper.     

A new method of making particleboard with a formaldehyde-free soy-based adhesive

A soy-based formaldehyde-free adhesive consisting of soy flour (SF) and a curing agent (CA) has been successfully used for the production of plywood. However, this adhesive cannot be easily sprayed onto wood particles for making particleboard because of its high viscosity. The following new method of using this adhesive was developed and investigated. SF was first mixed with water to form dilute soy slurry that could be easily coated onto wood particles. The soy-coated wood particles were dried to certain moisture content and then further coated with an aqueous curing agent. Effects of particleboard density, adhesive usages for both core and face particles, the solids content of the soy slurry, hot-press time, hot-press temperature, the storage time of the wet soy-coated wood particles, and the SF/CA weight ratio on the internal bond strength (IB), the modulus of rupture (MOR), and the modulus of elasticity (MOE) of particleboard were investigated.     

Evaluation of accelerated carbonation curing in cement-bonded balsa particleboard

This study aimed to assess the potential usage of balsa wood to produce cement-bonded particleboards as well as to study the effects of accelerated carbonation on the cement-bonded balsa particleboard. Particleboards were subjected to two different curing conditions, (1) conventional curing: control—curing for 48 h in a climatic chamber, followed by 25 days in a saturated environment (98?±?2%) in sealed plastic bags at 23 °C, (2) accelerated carbonation—curing for 48 h in a climatic chamber, and then in environment with CO₂ (24 h concentration of 15%), followed by 24 days in a saturated environment (98?±?2%) in sealed plastic bags at 23 °C. After 28 days of curing, the particleboards degree of carbonation was evaluated by TG-DTG and XRD analysis. Thermal, physical and mechanical characterizations were conducted following the recommendations of ASTM-E1530 and DIN: 310, 322, 323 standards, respectively. Accelerated carbonation decreased the portlandite content and increased of calcium carbonate content of the studied particleboards. Thermal properties showed that the particleboards could be used as an insulation material in accordance to European Standard (BS EN 13986). Physical and mechanical properties of the studied materials showed that they are potential building particleboard, because this material satisfied the requirements of ISO 8335 standard.     

Evaluation the effects of edge banding type and thickness on the strength of corner joints in case-type furniture

Edge banding is used to cover the exposed sides of wood materials such as plywood, particleboard or medium-density fiberboard, giving the appearance of a solid (or more valuable) material. This study was carried out to determine the effects of the edge banding material, namely polyvinyl chloride (PVC), melamine and wood veneer, thickness of edge banding material (0.4, 1, and 2 mm), and wood composite panel type on the diagonal compression and tension strength properties of particleboard surfaced with synthetic resin sheet (LamPb) and MDF surfaced with synthetic resin sheet (LamMDF).     

无机杨木刨花板制备及性能

以杨木刨花和无机胶黏剂为主要原料,通过冷压成型工艺制备了无机杨木刨花板,研究了不同施胶量和密度对无机杨木刨花板物理力学性能的影响,通过XRD和SEM分析了不同施胶量及密度对无机杨木刨花板性能的影响机制,同时通过锥型量热仪分析了无机杨木刨花板的阻燃抑烟性能。结果表明:一方面,随着施胶量增大,无机杨木刨花板静曲强度(MOR)和弹性模量(MOE)先增大后减小,同时,内结合强度(IB)逐渐增大,24 h吸水厚度膨胀率(TS)逐渐减小。施胶量为57%时MOR和MOE分别达到最大值21.5 MPa和4360 MPa,施胶量为65%时IB达到最大值2.61MPa,24 h TS达到最小值3.36%。随着施胶量增大,燃烧的峰值热释放速率(HRR)降低,HRR到达峰值的时间推迟,总热释放量(THR)和总生烟量(TSP)减少。另一方面,随着密度增大,MOR、MOE均逐渐增大,IB先增大后减小,24 h TS先减小后增大,无机杨木刨花板密度为1.1 g/cm3时IB达到最大值3.54 MPa,24 h TS达到最小值3.99%。      

Novel lignocellulosic hybrid particleboard composites made from rice straws and coir fibers

Novel lignocellulosic hybrid particleboard composites with low cost and high performance using the mixture of rice straws and coir fibers were developed in this work. NaOH (sodium hydroxide) aqueous solution was used to remove the wax and silica layer of rice straw surface. The effects of rice straws/coir fibers (R/C) mass ratios on the physical (thickness swelling) and mechanical (modulus of rupture, modulus of elasticity and internal bond strength) properties of particleboard composites were investigated. The results show that NaOH treatment was an effective method for improving wettability of rice straw surface with smaller contact angles and larger diffusivity–permeability constant. The SEM (scanning electron microscope) observation also gave some evidences such as more rough surface and less number of silica cells after NaOH treatment for improving wettability of rice straw surface. The coir fibers content had a significant negative linear effect on the bending properties and thickness swelling, but a significant positive linear effect on the internal bonding strength due to the lower wax and holocellulose content of coir fiber. When no diisocyanate resin applied, the particleboard composites made with only phenol formaldehyde resin at the optimal R/C ratio satisfied the requirements for load-bearing boards used in dry conditions based on Chinese Standard, indicated that the mixture of rice straws and coir fibers to make high quality particleboard composites was a cost-effective and environment friendly approach.     

Characterization of raw materials and manufactured binderless particleboard from oil palm biomass

The objective of this study was to examine the extractive, holocellulose, alpha cellulose, lignin, starch, and sugar contents of oil palm biomass and to evaluate its suitability in binderless particleboard production. In this study, bark, leaves, fronds, mid-parts and core-parts of the trunks were used to produce experimental binderless particleboard panels. Binderless particleboard panels were made with a target density of 0.80 g/cm³ at a temperature of 180 °C and a pressure of 12 MPa in a computer controlled hot press. The modulus of rupture, the internal bond strength, the thickness swelling and the water absorption of the panels were evaluated. Fourier transform infrared spectroscopy and field emission scanning electron microscopy were used to characterize the properties of the raw materials and the manufactured panels. The chemical composition of the oil palm biomass consisted of high holocellulose, lignin, starch and sugar contents that have been found to aid in the production of binderless particleboard. The core-part of the trunk contained the highest amount of starch and total sugar. Samples made from the core-parts and fronds had sufficient modulus of rupture and internal bond strength to meet the Japanese Industrial Standard. The internal bond strength of the mid-part panels also met the standard. However, binderless board prepared from bark and leaves showed poor modulus of rupture and internal bond strength. Samples from the core-parts had the lowest thickness swell and water absorption but did not meet the above standard. The Fourier transform infrared spectroscopy spectra did not show any substantial difference between the raw materials and the manufactured panels. Field emission scanning electron microscopy indicated that the compressed cells varied between raw material types and showed the presence of compressed cells with some starch granules that facilitated adhesion. Based on the findings of this study, oil palm has the potential to be used to manufacture binderless panel products, and further study is required to improve its dimensional stability.     

Design of a low-density wood-cement particleboard for interior wall finish

Gypsum boards form a very large part of the building walls and ceilings finishing market. However, they have poor screw-withdrawal resistance, low hardness and are highly sensitive to moisture. The objective of this study was to determine whether it is possible to make wood-cement particleboards of the same density as gypsum boards while avoiding these drawbacks.Wood-cement particleboards were made by pouring the wood-cement paste in a mould. This was made possible by adding a viscosity modifying mixture to the mixing water and a set accelerating mixture to improve wood/cement compatibility. The mechanical properties and surface quality of the wood-cement particleboards were improved by using, on the board surfaces, paper sheets that were the same as those used on gypsum boards.The average specific gravity of the wood-cement particleboards was the same as gypsum boards, at 0.7. The average bending modulus of rupture obtained for the wood-cement particleboards was 10 MPa in the finishing paper principal direction and 5 MPa in the other direction compared to 5.5 MPa and 1.6 MPa respectively for gypsum boards. The average screw-withdrawal resistance of wood-cement particleboards was 570 N, that is, 1.7 times higher than for gypsum boards.     

Effect of treated particles on the properties of particleboard made from oil palm trunk

The objective of this work was to evaluate the properties of particleboard made from oil palm (Elaeis guineensis) trunks treated with hot water and sodium hydroxide (NaOH). Experimental panels were manufactured from oil palm particles soaked in hot water for 30 min and soaked in NaOH with 2% concentration for the same time span. Urea formaldehyde adhesive was used for both types of particles as binder. Bending, internal bonding strength, thickness swelling and water absorption of the panels were tested. Scanning electron microscopy and fourier transform infrared spectroscopy were employed to analyze the properties of raw materials and manufactured panels. Based on the findings in this study, samples made with raw material treated with hot water resulted in 863.93 MPa modulus of elasticity and 7.09 MPa modulus of rupture which were higher than those of control panels and made from NaOH treated particles. Internal bond strength of the specimens also followed the similar trend. Both treatments improved the dimensional characteristics of the specimens.     

麦秸/木材均质复合无机碎料板的制备及其性能

以麦秸、木材和环保阻燃无机胶黏剂为主要原料,通过麦秸和木材碎料均匀混合的方式,采用热压工艺制备麦秸/木材均质复合无机碎料板,研究了麦秸与木材的配比、施胶量、热压时间和热压温度对板材性能的影响,并通过X射线衍射仪、扫描电镜分析了其对板材性能的影响机制。结果表明,随着麦秸与木材配比减小,板材静曲强度(MOR)、弹性模量(MOE)和内结合强度(IB)逐渐增大,2h吸水厚度膨胀率(TS)逐渐减小,优选配比为m(麦秸)∶m(木材)=4∶6。随着施胶量的增大,板材的MOR、MOE先增大后减小,IB逐渐增大,TS逐渐减小。施胶量为63%时,板材的MOR、MOE分别达到最大值15.5 MPa、3 110 MPa,此时,IB、TS分别为0.47 MPa、5.5%。随着热压温度的升高和热压时间的延长,板材的MOR、MOE、IB逐渐增大,TS逐渐减小。热压温度和热压时间分别为100℃、30min时,MOR、MOE、IB分别达到最大值(16.8 MPa、3 350 MPa、0.56 MPa),TS达到最小值(3.5%)。优化制板工艺为m(麦秸)∶m(木材)=4∶6,施胶量63%,热压时间30min,热压温度100℃。     

Water absorption behavior and mechanical properties of lignocellulosic filler–polyolefin bio-composites

To determine certain physical properties, viz. the thickness swelling and water absorption, and mechanical properties, viz. the tensile strength and Izod impact strength, of lignocellulosic filler reinforced polyolefin bio-composites, polyolefin was used as the matrix polymer and rice-husk flour as the reinforcing filler. Wood flour was also used as a reinforcing filler, and commercial particleboard, medium-density fiberboard and solid woods (red pine and birch) were also included in this study, in order to obtain comparative water absorption behavior measurements. Test samples were prepared, in order to determine the physical and mechanical properties of the bio-composites as a function of filler loading and according to filler type as well as with respect to the thermoplastic polymer itself. The thickness swelling and water absorption of the bio-composites slightly increased as the filler loading increased, but to a negligible extent as compared with the wood-based composites (particleboard and fiberboard) and the solid woods (red pine and birch). The mechanical properties of the composites decreased as the filler loading increased, but the composites had an acceptable strength level. It was concluded that these bio-composites are suitable to be used for the interior of bathrooms, wood decks, food packaging, etc.     

基于玉米醇溶蛋白胶粘剂的刨花板力学性能

为了开发利用玉米淀粉加工残余物(玉米醇溶蛋白)及制备环境友好刨花板,研究了二氯甲烷、玉米醇溶蛋白、制胶时搅拌温度等因素对基于玉米醇溶蛋白胶粘剂的木刨花板力学性能的影响。结果表明,当溶剂中二氯甲烷的体积百分含量在10%～50%范围内增加时,刨花板的静曲强度、弹性模量、抗拉强度及内结合强度等力学性能均呈现先增加后下降的趋势,当二氯甲烷含量为20%时,刨花板的各项力学性能达到最佳;当玉米醇溶蛋白的百分含量在20%～40%范围内增加时,刨花板的各项力学性能也均呈现先增加后下降的趋势,当玉米醇溶蛋白含量为30%时,刨花板的各项力学性能达到最佳;当制胶温度在25℃～65℃范围内增加时,刨花板的各项力学性能均呈现下降趋势,当温度为25℃时,刨花板的各项力学性能最佳。实验室测得玉米醇溶蛋白胶粘剂制备的刨花板力学性能值达到国家标准(GB4897-2003)。     

An experimental method for measurement of strain distribution between wood the flour particles and polymer matrix on micro-mechanical level

Wood plastic composites (WPCs) are comprised of wood flour and thermoplastic polymer. The matrix is typically high-density polyethylene, poly (vinyl chloride), or polypropylene. The effect of morphology and micromechanics of wood flour particles on the mechanical performance of the bulk composite is a relatively unexplored area. The knowledge about the in situ properties of wood particles and the interfacial properties between the wood particles and the polymer matrix in the bio-composites is very limited. The objective of this work is to characterize the full-field deformation and strain distribution in and around wood particles embedded in polymer matrix. The mechanical tests are performed in small-scale tensile loading stage on thin composite samples containing 1-3 wood particles orientated at various angles. The deformations and strains is measured using optical measurement system based on Digital Image Correlation (DIC) principle.