Medium Density Fiberboard Panels Research Articles

Comparison Failure and Successful Methodologies for Diffusion Measurements Undertaken inside Two Different Testing Rooms

The scattering phenomenon is known to be of great importance for the acoustic quality of a performance arts space. The scattering of sound can be achieved in different ways: it can be obtained by the presence of architectural and/or decorating elements inside a room (e.g., columns, statues), by the geometry and roughness of a surface (e.g., Quadratic Residue Diffuser (QRD)) and by the diffraction effect occurring when a sound wave hits the edges of an obstacle. This article deals with the surface scattering effects and the diffusion phenomenon only related to MDF and plywood panels tested by disposing the wells both horizontally and vertically. The test results undertaken inside a semi-reverberant room and inside a large reverberant room have been compared to highlight the success and the failure of the measuring methodologies. In detail, according to the existing standards and regulations (i.e., ISO 17497—Part 2), diffusion measurements have been undertaken on a few selected types of panel: two QRD panels (made of Medium Density Fiberboard (MDF) and plywood) with and without a smooth painted solid wood placed behind the QRD. The panels have been tested inside two rooms of different characteristics: a semi-anechoic chamber (Room A) and a large reverberant room (Room B). The volume size influenced the results that have been analyzed for both chambers, showing an overlap of reflections on panels tested inside Room A and a clear diffusion response for the panels tested inside Room B. In terms of the diffusion coefficient in all the octave bands between 125 Hz and 8 kHz, results should not be considered valid for panels tested in Room A because they were negatively impacted by extraneous reflections, while they are reliable for panels tested in Room B.

Simultaneous Improvement of Formaldehyde Emission and Adhesion of Medium-Density Fiberboard Bonded with Low-Molar Ratio Urea-Formaldehyde Resins Modified with Nanoclay

In wood-based composite panels, low-molar ratio (LMR) urea-formaldehyde (UF) resins usually result in reduced formaldehyde emission (FE) at the expense of poor adhesion. However, the FE and adhesion of medium-density fiberboard (MDF) bonded with LMR UF resins were both improved in this study. The modified LMR UF resins with transition metal ion-modified bentonite (TMI-BNT) nanoclay simultaneously improved the FE and adhesion of MDF panels. The modified LMR UF resins with 5% TMI-BNT resulted in a 37.1% FE reduction and 102.6% increase in the internal bonding (IB) strength of MDF panels. Furthermore, thickness swelling and water absorption also significantly decreased to 13.0% and 24.9%, respectively. These results imply that TMI-BNT modification of LMR UF resins could enhance the formation of a three-dimensional network rather than crystalline domains, resulting in improved cohesion.

Granulometric Characterization of Wood Dust Emission from CNC Machining of Natural Wood and Medium Density Fiberboard

The aim of this paper was to determine the particle size composition of wood dust emission from CNC milling of natural wood and medium-density fiberboard (MDF) and evaluate the associated occupational exposure risks. The paper is focused on some of the most commonly used materials in the woodworking and furniture industry, i.e., solid wood (beech, oak, and spruce) and composite materials (MDF panels). In addition to the influence of the machined material, the effect of the technical-technological parameters, namely, feed speed and depth of cut on the particle size distribution, was also investigated. The selected values of the technical-technological parameters used in this study followed the common work practice in small wood processing companies. The particle size distribution was evaluated by using sieve analysis of samples from the total mass of collected wood dust. The results demonstrated that machining of natural wood is characterized mostly by the formation of coarse dust fractions (2 mm–1 mm sieves), whilst the processing of MDF was associated with generation of fine dust fractions with a size below 100 μm. The results obtained can be used for optimizing the technological programs of CNC milling machines, thus, reducing the occupational exposure to harmful wood dust emissions in the wood-processing industry.

Urea impregnated multiwalled carbon nanotubes; a formaldehyde scavenger for urea formaldehyde adhesives and medium density fiberboards bonded with them

AbstractMultiwalled carbon nanotubes (MWCNTs) were subjected to modification by urea to use as formaldehyde scavenger in urea formaldehyde (UF) adhesive and reducing the free formaldehyde emission of the medium density fiberboards (MDFs). Morphological differences besides elemental analysis was investigated using field emission scanning electron microscopy (FESEM) and energy dispersive X‐ray spectroscopy. The effect of urea impregnated MWCNTs filler on the physical, morphological and thermal properties of the UF resin has investigated. Furthermore, characterization of the mechanical properties, free formaldehyde emission and thickness swelling were carried out for the MDF panels. From the results, the free formaldehyde of the UF resins was significantly decreased. The lowest free formaldehyde was belonged to the sample with 3 wt% of scavenger which was about 71% lower than the value for neat UF resin. Accordingly, the formaldehyde emission of the fiberboards was also showed a descending trend by incorporation of MWCNTs‐U to the composite structure. It was decreased from 9.67 to 3.89 mg/100 g dried board. These results indicated that the prepared nano modifier was successfully performed as a formaldehyde scavenger for the UF resin and could prevent the hazards of the free formaldehyde emission from MDF panels.

Influence of needle-punching treatment and pressure on selected properties of medium density fiberboard made of bamboo (Dendrocalamus strictus Roxb. Nees)

ABSTRACT In this study, Medium Density Fiberboard (MDF) was manufactured from bamboo (Dendrocalamus strictus Roxb. Nees) fibers and phenol-formaldehyde (PF) resins at different hot-pressing pressures using a novel needle-punching treatment to improve the properties of the panel. One-, two-, three- and four-time needle-punching treatments (1TP, 2TP, 3TP, and 4TP) were used in this work. Laboratory MDF panels were prepared by mixing bamboo fibers with 10% of PF resins. The needle-punching treatments were applied simultaneously on resinated bamboo fibers during the mat formation. The MDF mats were then hot-pressed at 14.0, 17.5, 21.0 kg/cm2 and at 150 °C for 15 min. Thereafter, the physical and mechanical properties of MDF panels were evaluated as per Indian Standard (IS) specification IS: 12406. It was observed that the combination of novel needle-punching technique and hot-pressing pressure enhanced the physical and mechanical properties of MDF panels. Statistical analysis suggested that a combination of 3TP and 21.0 kg/cm2 of pressures produced the MDF panel with satisfactory results. The research indicated that a combination of needle-punching treatment and hot-pressing pressure could be an excellent technique to improve the properties of the MDF panel.

An Investigation of Flexural Behavior of Pure and Hybrid Wood Composite Panels Using Weibull Analyses

The production of inexpensive wood products compared to their strength is important both in terms of economy and meeting the expectations of users. For this purpose, the use of hybrid wood products is increasing in the furniture industry. With the hybridization process, relatively cheap and flimsy material is combined with a material that has a stronger structure. Thus, stronger bonded material is manufactured cheaper. In this study, the flexural behavior of pure and hybrid wood composite panels, which were prepared by applying longitudinal jointing techniques from different wood materials, was investigated. In this context, pure chipboard, pure medium density fiberboard (MDF), chipboard-east beech and MDF-east beech hybrid wood composite panels were produced. During the hybridization process, oriental beech was combined by using the self-grooving technique in three different numbers as one row, two rows, and three rows. Flexural test results were analyzed according to the Weibull distribution method. The results of the analyses showed that the hybridization process increased the flexural strength and flexural modulus of pure wood panels by up to 214 %, and 95 %, respectively.

Influence of Non-Lignocellulosic Elements on the Combustion of Treated Wood and Wooden Panel

Brazil stands out internationally in the production and commercialization of wood products. Although the external and internal demand for these products is met by the Brazilian forestry sector, challenges related to the internal management of lignocellulosic waste are evident, as the country has structural difficulties in the sector of solid waste management. Therefore, the objective was to comparatively analyze the performance of the most abundant lignocellulosic materials in the Brazilian market, regarding energy recovery at the end of their life cycles. Pine wood treated with chromed copper arsenate (CCA), untreated pine wood, eucalypt wood treated with CCA, untreated eucalypt wood, uncoated medium density fiberboard panel (MDF), and MDF panel with melamine coating were sampled. The characterization included thermogravimetric analysis (TGA), scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDXA), and elementary analysis (EA). The presence of the CCA salts and the melamine coating reduced the energy potential of the biomass, altering the burning behavior and significantly increasing the amount of generated ashes. They also caused an increase in the concentrations of copper (Cu), chromium (Cr), arsenic (As), and cadmium (Cd) in the wood ashes as well as lead (Pb) and chromium in the panel ashes.

Wollastonite to Improve Fire Properties in Medium-Density Fiberboard Made from Wood and Chicken Feather Fibers

Poultry is a crucial global protein source.However, processing creates sizable quantities of feathers as a by-product. Identifying suitable uses for these feathers poses a major challenge. One possible use would be as an extender in medium density fiberboards (MDF). At the same time, feathers might also modify the inherent fire resistance of the resulting panels, suggesting the need for additives to enhance fire performance. The potential for using feathers to supplement wood in MDF panels was evaluated in conjunction with the addition of wollastonite. The effects of using 5% or 10% feathers with or without 10% wollastonite were investigated. Adding 5% feathers did affect properties. However, simultaneous addition of 10% wollastonite resulted in panels with improved fire performance properties and increased the ability of panels to dissipate heat. The results suggest that feathers could be a resource for extending timber supplies for MDF production, especially with wollastonite to improve fire performance.

Formaldehyde emission, combustion behavior, and artificial weathering characteristics of electrostatic powder coated wood composite panels

ABSTRACT Recently, research and development works have expanded to include the application of electrostatic powder coatings on non-conductive materials such as plastic, wood, and wood-based composite panels. Within the scope of this research, low temperature curing (120–130°C) was applied to wood-based composite panels of medium-density fiberboard (MDF), particleboard, and plywood panels to facilitate conductivity. Epoxy, polyester, and hybrid (epoxy-polyester) types of powder coating and waterborne acrylic liquid coating were applied to the surface of the materials. The panels coated with the powder coatings were compared to the panels coated with the waterborne acrylic resin coating (control group). Combustion behaviors was determined according to ISO 13927 standard, formaldehyde emission according to TS EN 717-2, and color and gloss changes after accelerated weathering according to ASTM G151 and ASTM G154. The best results for combustion behavior were obtained with the plywood panels and MDF panels coated with waterborne acrylic coating, for formaldehyde emission with plywood panels coated with epoxy powder coating and waterborne acrylic coating and plywood panels, MDF panels, and particleboard coated with polyester powder coating. The least color change and gloss loss were detected in the plywood panels, particleboard, and MDF panels groups with polyester-based powder coating.

Energetic characterization and radiographic analysis of torrefied coated MDF residues

The use of wood panel residues as biomass for energy production is feasible. Heat treatments can improve energy properties while minimizing the emission of toxic gases due to thermoset polymers used in Medium Density Fiberboard (MDF) panels. Torrefaction or pre-carbonization, a heat treatment between 200 and 300 °C with low oxygen availability accumulates carbon and lignin, decreases hygroscopicity, and increases energy efficiency. The objective of this work was to evaluate the energy parameters (immediate, structural, and elementary chemical composition, moisture content, and yield) and density in torrefied MDF panels. The torrefaction improved the energetic features of coated MDF, decreasing the moisture content, volatile matter, and consequently, concentrating the carbon with better results in the samples torrefied for 40 min. The densitometric profiles of the torrefied MDF, obtained by X-ray densitometry, showed a decrease in the apparent density as torrefaction time increased. The digital X-ray images in gray and rainbow scale enabled the most detailed study of the density variation of MDF residues.

The Removal of Cured Urea-Formaldehyde Adhesive towards Sustainable Medium Density Fiberboard Production: A Review

Medium density fiberboard (MDF) is an engineered wood product that has density and specific gravity similar to solid wood, ranging from 600 to 800 kg/m3 of density and 0.6 to 0.8 of specific gravity. This makes MDF suitable to partially replace solid wood, particularly for interior application. Approximately over than 100 million m3 of MDF are produced in 2020, resulting in a large amount of waste MDF will be generated in the next 20 years. MDF is produced using urea-formaldehyde (UF) resins adhesive. UF resins adhesive is a poly-condensation product of urea and formaldehyde via an alkaline acid two-step reaction. Sustainable MDF production is required as the world is facing climate change and deforestation. Recycling is a way to support sustainable production in the engineered wood products manufacturing. Many attempts have been done to find ways to recycle waste MDF. The main problem is UF resins, which bond the MDF panel fibers. In order to re-manufacture the waste MDF into new recycled MDF, UF resins should be eliminated from the waste MDF before being used. The presence of UF resins in MDF can interfere with the utilization of the recycled fibers, whether it will be used as a raw material for new MDF or other composite products. This paper reviews the process of removal of cured UF resins from waste MDF panel by considering the hydrolytic stability of cured UF resins for MDF recycling, providing a comprehensive review of how cured UF resins can be removed from waste MDF and characterization of recycled fibers obtained from recycling prior to re-manufacturing of recycled MDF panel.Keywords: hydrolysis, medium density fiberboard, resin, recycling, resin removal, urea-formaldehyde

The combined effects of alkali treatment and ammonium bicarbonate addition on selected properties of MDF panels

Effects of alkali treatment and ammonium bicarbonate were studied relative to selected properties of medium-density fiberboard (MDF) panels. Wood fibers were subjected to alkali treatment with sodium hydroxide or sodium perborate monohydrate (SPM). The MDF panels were produced from untreated and alkali treated fibers with or without ammonium bicarbonate (ABC). The modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding (IB), thickness swelling (TS), water absorption (WA), and limiting oxygen index (LOI) of the MDF were analyzed. The mechanical, physical, and fire resistance properties of MDF samples showed differences depending on the experimental parameters used. The lowest TS and WA values were found in the untreated-control group. The highest value for MOR and MOE was found for the group with the addition of 8% ABC. The IB values generally were higher than the untreated-control value. The highest value was determined in the group ABC8. Remarkably higher LOI values were achieved in the LOI test, especially for the groups with the application of both alkali treatment and ammonium bicarbonate.

Mechanical and formaldehyde-related properties of medium density fiberboard with zeolite additive

Zeolite was investigated as a potential component in the production of medium-density fiberboard (MDF). A mixture of beech (40%), oak (30%), and pine (30%) wood chips was used for fiber production. Chips were cooked for 4 min in an Asplund defibrator with a vapor pressure of 8 bar, and a temperature of 180 °C. Chemicals were added on fibers in the blow line. The resins were added at 11 wt% based on oven-dried wood fibers. Ammonium sulphate was added at 0.72 wt% based on resins. Paraffin wax was added as 1.8 wt% based on resin. Zeolite was prepared in a separate tank for its use instead of lignocellulosic fibers in the production of 1 m³ MDF. The fibers were dried to 12% moisture. A temperature of approximately 190 °C and a pressure of approximately 32 kg.m-² were applied to the mixture for 280 s to make MDF panels (500 x 490 x 14 mm). Mechanical properties of MDF boards were significantly increased for bending (MOE) and elastic modulus (MOR), but a little negatively affected on internal bond (IB), physical properties were negatively increased thickness swelling (ThS) and water absorption (WA). Consequently, increasing zeolite minerals in MDF boards showed best results of formaldehyde emission properties of MDF.

Effects of Adsorption Energy on Air and Liquid Permeability of Nanowollastonite-Treated Medium-Density Fiberboard

Change in air and liquid permeability by addition of nanowollastonite (NW) to medium-density fiberboard (MDF) was studied. MDF was produced by mixing camel-thorn (CT) chips to wood fibers. CT content was up to 10% of the mixture. Addition of CT did not significantly affect air permeability in control specimens. Water permeability time values were significantly higher in comparison to the other two liquids (alcohol and kerosene), indicating lower liquid permeability of MDF panels for water. In this connection, calculation of adsorption energies showed the formation of stronger and more stable bonds between water molecules with the cellulose surface in comparison to kerosene and ethyl alcohol. Formation of stronger bonds made movement of water molecules through MDF texture more difficult, ultimately resulting in lower water permeability in MDF specimens.

Addition of cellulose nanofibers extracted from rice straw to urea formaldehyde resin; effect on the adhesive characteristics and medium density fiberboard properties

In this research cellulose nanofibers (CNF) were successfully extracted from rice straw through a chemomechanical method and then mixed with urea-formaldehyde (UF) adhesive for the production of medium density fiberboard (MDF). The industrial grade liquid urea-formaldehyde (UF) resin with formaldehyde: urea molar ratio of 1.15 was modified by adding 0.5, 1.5 and 2 wt % of nanofibrillated cellulose (CNF) based on UF resin solids. The morphology, gel time, viscosity, and the non-volatile solid content of the modified UF adhesive were investigated. Formaldehyde emission and some mechanical properties modulus of rupture (MOR), modulus of elasticity (MOE) and internal bond strength (IB)) of the resulting MDF panels were measured. Solids content and viscosity of the UF adhesive decreased while gel time increased by mixing CNF with the resin. The formaldehyde emission of the panels made with UF containing CNF was lower than that of the panels made from neat UF while MOR, MOE and IB values increased by increasing the CNF content in the panels.

Evaluating the Delamination in the Drilling Process of a Melamine Coated Medium Density Fiberboard (MDF)

Medium density fiberboard (MDF) is an engineering product that is used in many industrial and general applications such as the furniture industry and kitchen cabinets. Generally, MDF products are generated by screw joints using the drilling process. However, the drilling process of the MDF panels leads to the delamination at the entrance and exit of the drill bit that should be controlled. In this work, the effect of the processing parameters including the feed rate and cutting speed on the delamination of melamine coated MDF is investigated. For this, two different tools with different tool geometry (a brad point drill bit and a commonly used twist drill bit) are examined. Image processing is used to measure the conventional delamination factor together with a new delamination factor referred to as area delamination factor for the drilled holes. It that the delamination value decreases with increasing cutting speed and increases with increasing feed rate. Though, there were some fluctuations in the results. The trend of changing the delamination respect to the investigated parameters was the same for both applied drill bits; however, the smaller value of delamination is obtained using the twist drill bit. Using the proposed area delamination factor, the effect of process parameters on the delamination is presented with higher magnitudes but with the same behavior. This, together with the ability of characterization of the water absorption of drilled holes has made the area delamination factor a more appropriate parameter to evaluate the delamination. The overall results are consistent with previously published works.

Application of artificial neural network to predict the effect of paraffin addition on water absorption and thickness swelling of MDF

In this study, water absorption and thickness swelling values of medium density fiberboard (MDF) were modelled by artificial neural networks (ANN). MDF panels were produced with different rates of paraffin (0.0-control, 0.5, 1 and 1.5 %) at different press temperatures (170 and 190 °C). After conditioning of MDF, water absorption (WA) and thickness swelling (TS) of samples were carried out at specific intervals within 24 hours. Then, the data obtained from these experiment were modelled using ANN. Paraffin addition rate, press temperature and immersion time in water were used as the input parameters, while WA and TS values of MDF were used as the output parameters. After training of ANN, it was found that correlation coefficients (R) were close to 1 for training, validation, test and all data set. Mean absolute percentage error (MAPE) and mean square error (MSE) were determined as 2.94 % and 0.57, respectively, for all data sets. As a result of this study, the use of proposed ANN model may be recommended to predict the water absorption and thickness swelling of panels instead of complex and time-consuming studies such as empirical formulas.

Evaluation of modulus of elasticity and modulus of rupture of full-size wood composite panels supported on two nodal-lines using a vibration technique

The objective of this study was to determine the feasibility of using a transverse free vibration testing method to nondestructively evaluate the bending stiffness and strength of full-size (1220 × 2440 mm) wood composite panels (WCPs). Based on the principle of transverse free vibration of a thin plate, the dynamic modulus of elasticity (MOE) of a full-size WCP supported on two nodal-lines was derived using the Rayleigh method. Transverse free vibration test was conducted on 54 full-size medium density fiberboard (MDF) panels and 36 full-size particleboard (PB) panels under a two-nodal-line support. The modulus of elasticity (MOE) and modulus of rupture (MOR) of the panels were then determined by conducting static bending tests on the small samples cut from each panel. The results indicated that the transverse free vibration of a full-size panel supported on two nodal-lines was a valid testing approach for rapid determination of dynamic modulus of elasticity of full-size MDF and PB panels. Strong linear relationships were found between the dynamic MOE of full-size panels and static MOE of small samples, with the dynamic MOE approximately 8% higher than the static MOE. In addition, the two-variate models with dynamic MOE and thickness as predicting variables and the three-variate models with natural frequency, density and thickness as variables were found both effective in predicting the modulus of rupture of full-size MDF and PB panels.

Experimental Study on Drilling MDF with Tools Coated with TiAlN and ZrN.

There is increasing use of wood-based composites in industry not only because of the shortage of solid wood, but above all for their better properties such as: strength, aesthetic appearance, etc., compared to wood. Medium density fiberboard (MDF) is a wood-based composite that is widely used in the furniture industry. The goal of the research conducted was to determine the effect of the type of coating on the drill cutting blades on the value of thrust force (Ft), cutting torque (Mc), cutting tool temperature (T) and surface roughness of the hole in drilling MDF panels. In the tests, three types of carbide drills (HW) were used: not coated, TiAlN coated and ZrN coated. The measurement of both the thrust force and the cutting torque was carried out using an industrial piezoelectric sensor. The temperature of the cutting tool in the drilling process was measured using an industrial temperature measurement system using a K-type thermocouple. It was found that the value of the maximum temperature of the tool in the drilling process depends not only on the cutting speed and feed rate, but also on the type of coating of the cutting tool. The value of both the cutting torque and the thrust force is significantly influenced by the value of the feed rate and the type of drill coating. The effect of varying plate density on the surface roughness of the hole and the variation of the value of the thrust force is also discussed. The results of the investigations were statistically analyzed using a multi-factorial analysis of variance (ANOVA).

New insight into the use of latent catalysts for the synthesis of urea formaldehyde adhesives and the mechanical properties of medium density fiberboards bonded with them

Recently, there has been a rapid growth in research and innovation in the synthesis of UF resins in the wood-based composites area. Much effort has gone into increasing their mechanical performance to extend the capabilities and application of this group of materials. This paper, for the first time, defines the research on the use of ammonium salts not as hardeners but in the synthesis of UF resins. The objective of this study was to investigated the effects of various types of catalysts (ammonium sulfate, ammonium chloride, sulfuric acid and hydrochloric acid) during UF resins synthesis on formaldehyde emission and characteristics of urea–formaldehyde (UF) adhesives for the manufacture of medium density fiberboard. These were investigated by 13C Nuclear Magnetic Resonance (13C NMR) and differential scanning calorimetry (DSC), and as a result some of the physical and mechanical properties of medium density fiberboard (MDF) panels bonded with different UF resins were evaluated. The resins structure examined by 13C NMR spectroscopy showed that a resin catalyzed by (NH4)2SO4 had a higher proportion of hydroxymethyl groups (mostly HNCH2OH) resulting in a higher level of formaldehyde emission. A resin catalyzed by NH4Cl gave the highest proportion of methylene groups. A resin catalyzed by H2SO4 yielded the highest proportion of methylene groups in di- or tri-substituted ureas but the lowest proportion of mono-substituted urea. It was of interest that (NH4)2SO4 catalyzed UF adhesive yielded the best overall mechanical properties for the medium density fiber board (MDF) bonded with it. Conversely, it also presented the shortest shelf life and gelled in about 15 days, which could be related to its high reactivity and shortest gel time. Medium Density Fiberboard (MDF) panels bonded with UF adhesives without any ammonium salt (thus with either H2SO4 or HCl) had lower IB strength, MOR and MOE. The HCl catalyst was considered to be chemically least active, yielding the lowest cohesive energy, and resulted in panels presenting a poor performance as shown by their lowest IB (internal bond) strength, modulus of elasticity (MOE), and modulus of rupture (MOR) and highest thickness swelling, with the exception of the free formaldehyde content.