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.     

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.     

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.     

Effects of hardener type,urea usage and conditioning period on the quality properties of particleboard

The effects of hardener type (ammonium chloride, ammonium sulphate and aluminium sulphate), urea usage (with urea and without urea), and conditioning period (one day and one month) of the particleboard on the physical (thickness swelling), mechanical (modulus of rupture, modulus of elasticity and internal bond strength), surface properties, and formaldehyde emission of particleboard and acidity of the wood particles were investigated. The hardener type was found to be effective all of the properties of particleboard. The pH of the wood particle with the urea was slightly higher than that of particles without urea.The lowest pH value for the resinated wood particles was obtained from ammonium chloride, followed by ammonium sulphate and aluminium sulphate, respectively. The best quality properties were obtained from the particleboards manufactured with ammonium chloride, followed by particleboard made with the ammonium sulphate and aluminium sulphate, respectively. The urea usage significantly decreased the formaldehyde emission of the particleboards while it slightly decreased the mechanical properties and increased thickness swelling. Increasing conditioning period of the particleboards from one day to one month improved the quality properties.     

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.     

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.     

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.     

Influence of press temperature on the properties of binderless particleboard made from oil palm trunk

The objective of this investigation was to evaluate the properties of binderless particleboard manufactured from oil palm trunk as a function of press temperature. Particleboard samples were manufactured with a target density of 0.80 g/cm³ using press temperatures of 160 °C, 180 °C and 200 °C. The modulus of rupture, internal bond strength, water absorption and thickness swelling of the boards were determined based on Japanese Industrial Standards (JIS). Thermal gravimetric analysis, Fourier transform infrared spectroscopy and field-emission scanning electron microscopy coupled with energy dispersive X-ray analysis were employed to characterize the properties of the raw materials and the manufactured panels. The moduli of rupture of the samples were observed to increase with increasing press temperature, but they did not meet the standard values. However, the internal bond strength of the samples attained satisfactory values according to the JIS standard for all three temperature levels. Water absorption and thickness swelling of the boards decreased with increasing pressing temperature. Based on the findings in this study, increasing the pressing temperature may be considered a potential way of improving the properties of binderless particleboard.     

Properties of steam treated binderless particleboard made from oil palm trunks

The objective of this study was to evaluate both physical and mechanical properties of particleboard panels manufactured from steamed material of oil palm trunks without using any adhesives. Experimental panels from fine particles and vascular strands of oil palm were manufactured. Modulus of rupture (MOR), internal bond strength (IB), thickness swelling (TS) and water absorption (WA) of the samples were tested based on Japanese Industrial Standards. Bonding quality of such binderless samples was also evaluated by using scanning electron microscope (SEM). Based on the findings on this work steaming of the raw material enhanced overall mechanical and physical characteristic of the samples. The highest MOR values of 8.12 MPa and 25.84 MPa were found for the samples made from fine particles and strands steamed at a temperature of 130 °C for 30 min, respectively. It appears that mechanical properties of the panels reduced when they exposed to beyond 30 min steaming time.     

Properties of particleboard made from rubberwood using modified starch as binder

The objective of the study was to evaluate physical and mechanical properties of experimental particleboard panels made from rubberwood (Hevea brasiliensis) using modified starch as binder. Panels were manufactured using 15% corn starch modified with glutardialdehyde and tested for their properties based on Japanese Standard. The modulus of rupture and the internal bond strength of the panels met the requirement of the specified standard. Based on the findings in this work modified corn starch can have a potential to be used as binder to produce particleboard panels with acceptable properties.     

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.     

Properties of binderless particleboard from oil palm trunk with addition of polyhydroxyalkanoates

This study evaluated the properties of binderless particleboard made from oil palm trunk with addition of polyhydroxyalkanoates in the form of freeze dried and pure samples. Modulus of rupture, internal bonding strength, thickness swelling and water absorption of the boards were evaluated based on Japanese Industrial Standards. Modulus of rupture and internal bonding strength increased as the amount of polyhydroxyalkanoates were increased. Thickness swelling and water absorption decreased with increasing percentage of polyhydroxyalkanoates. The surface roughness, gas chromatography, thermogravimetric analyses, Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and differential scanning calorimetry were also investigated. Based on the findings in this work, it appears that the addition of polyhydroxyalkanoates enhanced overall properties of such binderless panels.     

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.     

Dependencies between internal structure and mechanical properties of spray dried granules – Experimental study and DEM simulation

The mechanical properties of spray dried granules are decisive with regard to further applications and can be modified via internal granule structure. To obtain the correlations between structural and mechanical properties, necessary experiments are often time and resource consuming. The simulation of varied granule structures and their effect on resulting mechanical properties seems to be a promising approach.In this paper, a model of the particulate internal structure of a spray dried granule was generated with the Discrete Element Method (DEM) based on real structure parameters. The model considers real primary particle number, particle size distribution and radial granule inhomogeneity, what results in the implementation of granule shell thickness and macro void. The internal structure of simulated granules showed significant influence on their mechanical properties. An increase of granule shell thickness and packing density of the primary particles within the shell results in fracture strength increase accompanied by decreasing fracture strain. The simulated reduction of the solid bridge bond size between the primary particles representing the decreasing binder amount leads to decreasing fracture strength and strain as previously determined experimentally (Eckhard et al., 2014). Consequently, the DEM is appropriate for evaluating the effect of changed real internal structure parameters on resulting mechanical granule properties.     

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.     

The efficiency of tannin as a formaldehyde scavenger chemical in medium density fiberboard

The aim of this study was to determine the effect of tannin content of urea formaldehyde (UF) resin on the panel properties of medium density fiberboard (MDF). Tannin extracted from the bark of white oak (Quercus alba) was added to UF resin at different ratios (based on the resin) to decrease the free formaldehyde content of MDF panels in this study. It was determined that free formaldehyde values of MDF panels decreased when the ratio of tannin content in UF resin increased. However, the modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond strength (IB) of these panels were a little lower, and the thickness swelling (TS) (24 h) and water absorption (WA) (24 h) values were a little higher compared to the control MDF panels.     

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.     

Effect of particle geometry on the properties of binderless particleboard manufactured from oil palm trunk

Experimental binderless composite panels were manufactured using fine particles and strands of oil palm (Elaeis guineensis) trunks. Modulus of rupture (MOR), internal bond strength (IB), dimensional stability, and surface roughness of the panels made with a target density of 0.80 g/cm³ were evaluated. Strand type samples had MOR and IB values of 24.95 and 0.95 MPa, respectively. Corresponding values for the fine particle type samples were 4.04 and 0.49 MPa. Panels made from strands met MOR requirement stated in Japanese Industrial Standard (JIS). Enhanced bonding between strands observed by micrographs taken using scanning electron microscopy (SEM) also supported the findings. However, the samples having fine particles had lower MOR values than minimum requirement listed in JIS. Strand type panels had 41.6% thickness swelling which is only 4.6% lower than that of the panels made from fine particles. It appears that dimensional stability of both types of panels exhibited insufficient results according to JIS. Surface roughness quality of the samples made from fine particles had average surface roughness values comparable to those of panels made in past studies. Based on initial results of this work, raw material from oil palm trunks can have some potential to be used to manufacture binderless panels without using any adhesives. This study revealed that mechanical and physical properties of such experimental panels were influenced by the particle geometry. It would be important to consider possible addition of chemical or wax in the particles to improve their dimensional stability in further studies.     

Some of the physical and mechanical properties of cement composites manufactured from carbon nanotubes and bagasse fiber

The objective of this investigation was to evaluate physical and mechanical properties of experimental cement type panels made from multi-wall carbon nanotubes (MWCNTs) and bagasse fiber. Three levels of MWCNTs, namely 0.5 wt.%, 1 wt.% and 1.5 wt.% were mixed with 10 wt.% and 20 wt.% of bagasse fiber in rotary type mixer. Thickness swelling, water absorption, bending characteristics and impact strength of the samples were evaluated. Based on the findings in this work the water absorption and thickness swelling of the nanocomposites decreased with increasing amount of the multi-wall carbon nanotubes content in the panels from 0.5% to 1.5%. On the other hand flexural modulus and impact strength of the panels were enhanced with increased percentage of carbon nanotubes. Panels having 0.5% MWCNTs exhibited the highest impact strength. Overall dimensional stability and strength properties of the samples were adversely influenced with increased amount bagasse fiber in the samples. It appears that using lower percentage of bagasse fiber or application of heat or chemical treatment to the raw material should be considered to improve negative influence of bagasse fiber on properties of the panels.     

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%。