Medium Density Fiberboard Panels Research Articles

Eco-friendly fiberboards with low formaldehyde content and enhanced mechanical properties produced with activated soybean protein isolate modified urea-formaldehyde resin

Urea-formaldehyde (UF) resin is one of the most widely used resin adhesive for wood-based panels. The main concern of UF resin bonded wood-based panels is formaldehyde emission and poor water resistance. In this study, activated soybean protein isolate (SPI) was used to modify UF resin for the production of eco-friendly fiberboard panels. The effects of different activated SPI on the properties of UF resins and the resin bonded medium-density fiberboard (MDF) panels were investigated. The free formaldehyde content of the urea-activated SPI modified UF resin was only 0.13 %. Approximately 27.8 % lower than that of the unmodified UF resin. The resin bonded MDF panel with a density of 760 kg/m3 shows a modulus of rupture (MOR) and modulus of elasticity (MOE) of 45.73 MPa and 4005 MPa, which is increased by 25 % and 15 % compared to the unmodified UF resin group. The internal bonding strength (IB) reaches 0.71 MPa, which is about 15 % higher than that of the unmodified UF resin group. The tested 24-hour thickness swelling (24 h TS) of the modified UF resin group is only 8.1 %. The tested formaldehyde content of the sodium dodecyl sulfate (SDS)-activated SPI modified UF resin bonded MDF panel is only 4.8 mg/100 g, which is 20 % lower than that of the control UF resin group. The activated SPI modified UF resin shows great improvement in bonding strength and lower formaldehyde content for MDF panels as compared to the pure UF resin. The chemical groups, crystalline properties, and thermal stability of the pure and the modified UF resins were characterized via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric (TG) analysis. It is confirmed that the activated SPI modified UF resin has similar chemical structure, higher ratio of crystalline regions, and slightly lower thermal stability with compared to the pure UF resin. This study proposes a practical and applicable solution for the utilization of eco-friendly UF resin in wood-based panel production.

Utilizing de‐inked paper sludge for sustainable production of medium‐density fiberboard: A comprehensive study

AbstractThis study investigated converting abundant paper mill waste, de‐inked paper sludge (DPS), into value‐added medium‐density fiberboard (MDF) panels. The objective was to repurpose this solid waste into a valuable material that aligns with the principles of a circular economy. Previous research has examined the addition of paper sludge to wood composites, but there is limited information on the specific incorporation of DPS into MDF production. This investigation offers new insights into this application. MDF panels were manufactured using hardwood fibers, with varying levels of urea‐formaldehyde resin (10% and 12% by weight) and different loadings of DPS (ranging from 0% to 50% by weight). X‐ray diffraction analysis revealed the presence of defective DPS fiber crystals. Contact angle measurements confirmed that DPS had poor wettability, corresponding to increased water absorption. As more DPS was incorporated, the mechanical properties of the panels progressively weakened due to defective fibers and poor adhesion between the fibers and the matrix. This was evident in scanning electron microscopy micrographs, which showed an escalation in interfacial flaws. Increasing the resin dosage noticeably improved the internal bond strength and reduced moisture uptake across all levels of DPS. However, at a DPS loading of 50%, the properties of the panels deteriorated by 36%–57% compared to the control MDF. Additionally, thickness swelling and water absorption increased significantly with higher DPS content, primarily due to the hydrophilic nature of the fibers. Based on optimization, it was determined that a DPS loading of 20% with a resin content of 12% provided the best balance between performance, waste utilization, cost, and moisture resistance. The reuse of abundant paper sludge supports the goals of a circular economy. However, strategies are required to tailor the processing methods and enable higher levels of recycled material without excessively compromising the key attributes of the product. Further research should focus on enhancing the quality of DPS and its compatibility with wood fibers and resin to enhance the performance of the composite material.Highlights DPS from recycled paper mill assessed for MDF production with wood fibers and resin Increasing DPS loading caused reductions in strength and adhesion of panels Water absorption and thickness swelling markedly rose with more DPS addition It was attributed to hydrophilic fibers and disrupted fiber‐matrix bonding Optimal formulation was 20% DPS loading and 12% resin content, balancing performance, waste utilization, and cost.

Propriedades de painéis MDF fabricados com misturas de madeira de plantações de paricá e resíduos de madeira de espécies nativas da Amazônia

ABSTRACT Brazil stands out as one of the largest manufacturers of MDF (medium density fiberboard) in the world. The industries are concentrated in the south and southeast of the country and are primarily based on the use of Pinus and Eucalyptus wood, which are available in extensive planted areas. In the northern region, there is only one MDF industrial plant. Despite an abundance of potential raw materials in this region, there is a lack of studies on native species wood and their industrial waste utilization for MDF production. The present study aimed to evaluate the properties of MDF manufactured from a mixture of cultivated paricá (Schizolobium amazonicum) wood and wood waste from native Amazonian species. The study assessed the isolated effects of different proportions of the raw materials and panel thicknesses on MDF properties. Panels were produced, and samples were obtained for testing. Using standard procedures, the following properties were determined: density, water absorption, thickness swelling, internal bonding, static bending, and resistance to screw withdrawal. The results revealed a significant impact of the analyzed variables on some physical and mechanical properties of MDF. With the exception of internal bonding, all other properties of the evaluated MDF panels met the specified regulatory requirements for use in furniture manufacturing. It is concluded that mixtures of the assessed raw materials have great potential for MDF production in the furniture industry. However, adjustments in the production process are recommended to improve the internal bonding property.

The Impact of Hydrolysis Regime on the Physical and Mechanical Characteristics of Medium-Density Fiberboards Manufactured from Recycled Wood Fibers

Recycling medium-density fiberboards (MDF) presents notable technological challenges, primarily due to the deteriorated properties of the recycled wood fibers obtained from MDF waste. On the other hand, the enhanced valorization of recycled wood in the manufacturing of wood composites represents a viable approach for implementing the principles of a circular bio-economy in the wood-based panel industry and lowering its carbon footprint. This research aimed to investigate and evaluate the impact of the hydrothermal hydrolysis regime on the physical and mechanical properties of recycled MDF panels (rMDF). The hydrolysis temperature was varied from 121 °C (saturated steam pressure 0.2 MPa) to 134 °C (saturated steam pressure 0.3 MPa), and three hydrolysis durations, i.e., 30, 45, and 60 min, were applied. A control MDF panel, manufactured in laboratory conditions from industrial pulp, was used to perform the comparative analyses. It was observed that the degradation of the rMDF panels occurred when the hydrolysis temperature was increased from 121 °C to 134 °C. The research confirmed the deteriorated physical and mechanical properties of rMDF compared to the panels manufactured from natural wood fibers. Markedly, no significant differences were detected between the density profiles of the rMDF panels and the control boards fabricated from industrial pulp. As a result of the study, it was found that the hydrolysis temperature has a more significant effect than the processing time. It was also established that, in the preliminary preparation of the MDF panels into samples with dimensions similar to those of pulp chips, the optimal hydrolysis regime is at a temperature of 121° C (saturated steam pressure 0.2 MPa) and a time of 30 min.

Combining Artificial Neural Network and Response Surface Methodology to Optimize the Drilling Operating Parameters of MDF Panels

Most of the parts of furniture made of medium density fiberboards (MDF) require at least one hole to be assembled. The drilling technological parameters influence the quality of holes. Factors such as tip angle of the drill bit, feed rate, type and diameter of the drill bit, and spindle rotational speed could affect the drilling process. Therefore, the right choosing of drilling parameters is a mandatory condition to improve the drilling efficiency that is expressed through tool durability, cost, and quality of the drilling. Thus, in this work, we are proposed an approach that consists in combining two modelling techniques, which were successfully applied in various fields, namely artificial neural network (ANN) and response surface methodology (RSM), to analyze and optimize the drilling process of MDF boards. Four artificial neural network models with a reasonable accuracy were developed to predict the analyzed responses, namely delamination factor at inlet, delamination factor at outlet, thrust force, and drilling torque. These models were used to complete the experimental design that was requested by the RSM. The optimum values of the selected factors and their influence on the drilling process of the MDF boards were revealed. A part of optimum combinations among analyzed factors could be used both during the drilling of the MDF boards and prelaminated wood particleboards.

Impregnation of Medium-Density Fiberboard Residues with Phase Change Materials for Efficient Thermal Energy Storage

The wood-based panel industry generates a significant amount of solid residues in its production activities, including medium-density fiberboard (MDF) molding manufacturing. These residues consist of fine fibers measuring between 0.15 mm and 1.19 mm in length. A large proportion of them currently needs to be utilized, mainly due to the problem of excessive accumulation. They can be reused as raw material for manufacturing new products by adopting a circular economy approach. Their thermal properties can also be enhanced by impregnating them with phase change materials (PCMs). This research aims to develop a process for impregnating MDF panel residues (R) with PCMs to obtain shape-stabilized compounds capable of storing thermal energy. Three different commercially available PCMs were used. They were incorporated in the MDF residues by vacuum impregnation. The morphology, chemical structure, thermal stability, and phase change properties of the compounds obtained were studied by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), respectively. The SEM images indicated the PCM filled the empty spaces in the porous surface of the residue fibers to form shape-stabilized compounds. The FTIR spectrometry results indicated the compounds still exhibited characteristic peaks corresponding to both the MDF residues and the PCMs. No chemical reaction was observed between the two components. Moreover, according to the TGA results, the compounds produced exhibit high thermal stability. The R+PCM1 compound had the highest latent heat capacity of all the compounds developed in this study, reaching a maximum of 57.8 J⋅g−1, and a phase change temperature comparable to that of PCM1. This better thermal performance could be attributed to the compounds having a higher encapsulation ratio (31.4%) than the other compounds developed. Furthermore, the R+PCM1 compound had an absorption capacity of 142.8%. This study, therefore, unveiled a promising alternative for storing thermal energy and valorizing solid MDF residues.

Effect of Hydrolysis Regime on the Properties of Fibers Obtained from Recycling Medium-Density Fiberboards

Unlike the recycling of particleboards, the recycling of medium-density fiberboards (MDF) is not a widespread industrial practice, and currently, most waste MDF panels are landfilled or incinerated after the end of their life cycle. Therefore, it is of great importance to develop cost-effective methods for MDF recycling. The extraction of resins used for bonding the panels, mostly urea–formaldehyde (UF) resins, is carried out mainly with hydrolysis. Hydrothermal hydrolysis is a more environmentally friendly and cheaper recycling technique compared to acid hydrolysis and allows obtaining a high yield of recycled fibers. The aim of this research work was to investigate and evaluate the effect of hydrolysis regime applied on its efficiency and on the properties of the recycled MDF fibers. For this purpose, thermal hydrolysis was carried out in an autoclave with saturated steam as a heat carrier. The main novelty of the research is the preliminary preparation of the recyclable MDF in samples with dimensions close to those of pulp chips. The effect of hydrolysis regime characteristics, i.e., process time and temperature on the properties of recycled MDF wood fibers, was studied. The hydrolysis temperatures used were 121 °C (saturated steam pressure of 0.2 MPa) and 134 °C (saturated steam pressure of 0.3 MPa); for each temperature, three durations were applied—30, 45, and 60 min. After hydrolysis, the resulting fiber fraction was refined using a hammer mill. The fractional and elemental composition of the recycled fibers obtained were evaluated. The hemicellulose content after each hydrolysis treatment was also determined. The chemical oxygen demand (COD) was defined as an indicator of wastewater contamination and as an indirect indicator of the quantitative yield of the process. The results revealed no significant changes in the elemental composition of the recycled fibers, and the hydrolysis regimes used showed no decrease in pentosan content. The recycled MDF fibers exhibited similar fiber morphology and fractional composition, being shorter than fibers from industrial pulp. The increased temperature and time of hydrolysis resulted in a significant increase in COD values. Based on the obtained results, with a view to the slightest contamination of wastewater (as determined by COD), the most promising hydrolysis regime was at a temperature of 121 °C and a time of 30 min. It should be emphasized that for a confirmation of this statement, the properties of MDF panels fabricated with fibers recycled in different regimes should be subsequently investigated.

Modified graphene as potential additive for urea formaldehyde (UF) resin in medium density fiberboard (MDF) manufacturing

In this study, graphene oxide (GO) and ethylenediamine-functionalized graphene oxide (EDA-GO) materials were used as a multifunction additive in a UF resin to test the relevant effects on the release of formaldehyde from medium density fiberboard (MDF). The GO was synthesized from graphite using the modified hummers method. Then, the as-synthesized GO was functionalized with ethylenediamine (EDA). The as-synthesized and modified nanomaterials were characterized by XRD, Raman Spectroscopy, AFM, and SEM-EDS techniques. These tests confirmed that the nanomaterials were of the required quality, and they were added to the resin to make the relevant panels. After making the boards, they were tested to determine their physical and mechanical properties, as well as formaldehyde emission based on relevant standards. Modulus of elasticity and formaldehyde emission reduction of the EDA-GO3-treated MDF panel were with the highest values. On the contrary, the higher performance of GO than that of EDA-GO was observed in a thermal property (t100°C). Microstructure and polar increase in the graphite planes network, due to oxidation, may be considered for its GO effects. Amino-functionalization of graphene oxide planes is suggested as the cause of the minimum formaldehyde emission and the maximum modulus of elasticity in the EDA-GO-incorporated MDF board since resin reaction sites with formaldehyde were enhanced by increasing the amine group content.

Resistance of Untreated and Torrefied Medium-Density Fiberboard (MDF) Residues to Xylophage Fungi

The manufacture of wood panels generates a large amount of waste. This material can be an option for renewable energy generation. However, long-term storage, exposure to moisture and contact of these panels with the soil facilitate colonization by xylophagous organisms. Torrefaction, a heat treatment between 200 and 300 °C in an oxygen-free atmosphere, is a process that decreases hygroscopicity while increasing carbon content, energy efficiency and resistance to fungal attack. This work aimed to evaluate the resistance of MDF panel residues. The MDF panels were produced using eucalyptus wood and bonded with thermosetting synthetic resin, under high temperature and pressure, torrefied at 300 °C for 20, 30 and 40 min and exposed to the xylophagous fungi of the white rot, Irpex lacteus (Fr.) Fr. (1828) and Trametes versicolor, and that of the brown rot, Postia placenta. After the 12-week evaluation period under fungal exposure, the mass loss of the samples attacked by T. versicolor and P. placenta was similar between treatments, except the MDF untreated, which had greater mass losses from the fungus Irpex lacteus. The torrefaction process increased the material resistance to deterioration by fungi, with an inverse correlation between the torrefaction period and the mass losses by fungal attack of the MDF panel residues.

Application parameters of water transfer printing on wood-based panel surfaces

Optimum application values of the Water Transfer Printing (WTP) technique were determined on various wood-based panel surfaces. For this purpose, 8-mm-thick, glossy white, acrylic-coated medium-density fiberboard (MDF) panels (high gloss panels), polyvinyl chloride (PVC)-coated MDF panels, MDF Lam ready-to-use panels, and cellulosic, polyurethane, acrylic, and water-based paint applied MDF panels were used. An automatic immersion system with pool was designed and produced. A 30-μm-thick carbon patterned WTP film was applied on sample panel surfaces prepared with the help of this device at four immersion angles (0º, 15º, 30º, and 45º), four immersion speeds (50 cm/min, 100 cm/min, 150 cm/min, and 200 cm/min), and four immersion times (5 to 10 s, 20 to 30 s, 50 to 60 s, and 80 to 90 s). The optimum parameters of the WTP technique regarding the temperature and relative humidity of the application environment, water temperature, laying method, dissolution time, amount of activator, spray gun angle and tip clearance, air pressure, as well as immersion angle, speed, and time were determined using the measurement and observation method. According to the optimum parameters obtained in the study, the WTP technique was successfully applied to all wood-based panel surfaces.

Effects of CNC Processing Parameters on Surface Quality of Wood-Based Panels Used in Furniture Industry

The processing of wood-based panels such as plywood, particleboard and fiberboard, which are widely used in the furniture industry, with CNC (Computer Numerical Control) milling machines has been increasing recently. Even though CNC milling machines have many advantages for furniture producers, it is difficult to set process parameters to obtain the desired surface quality of the material. Therefore, it is necessary to determine the most suitable of these parameters for the surface quality of each wood-based panel. This study aimed to determine the effects of processing parameters on the surface quality of plywood, particleboard and medium density fiberboard (MDF) panels processed in CNC milling machines. Furthermore, the average surface roughness values of these panels were compared after CNC processing. Three spindle rotational frequencies (10.000, 14.000 and 18.000 rpm), three feed rates (5, 7, and 9 m/min) and two cutting tool diameters (2 and 5 mm) were selected as CNC processing parameters. To determine the surface quality of wood-based panels, the surface roughness measurements were performed according to DIN 4768 standard and three surface roughness parameters (Ra, Rmax and Rz) were determined. According to the results of this study, it can be concluded that the surface roughness values of wood-based panels decreased with increasing spindle rotational frequency and feed rate, while they increased with increasing cutting tool diameter. Among the wood-based panels used in this study, the lowest average roughness values were obtained for plywood samples.

Preparation and characterisation of electromagnetic shielding medium-density fiberboard using Iron oxide nanoparticles

ABSTRACT A special medium-density fiberboard (MDF) has been fabricated in order to electromagnetic shielding composite by adding iron oxide nanoparticles (NF) to wood fiber (WF). The aim of this work was to study the panel properties with different loadings (1, 3, 5, 7, and 10 wt %) of Fe3O4 nanoparticles. The mechanical, physical, and Electromagnetic (EM) shielding properties of the produced fiberboard were analyzed. The maximum shielding effectiveness (SE) was 13.6 dB for the NF10 in the frequency range of 8.2–12.4 GHz and the absorption had the main contribution to the SE of the panels rather than the reflection. Internal bonding (IB) of the MDF panel was increased by 8.5% by adding 1% Fe3O4 nanoparticles. After that, the IB decreased compared to the control one. The modulus of rupture (MOR) and modulus of elasticity (MOE) of the MDF panels were less than the control panel. The MOR, MOE, IB, thickness swelling (TS), and water absorption (WA) of the panel with 10% Fe3O4 nanoparticles (NF10) panel showed 21.5, 2489, 0.56 MPa, 13.4%, and 61.4%, respectively. Generally, the fiberboard fabricated with 10% Fe3O4 nanoparticles indicated the ability for Electromagnetic shielding applications because of their acceptable properties according to the EN622-5 standard and appropriate EM shielding.

Biological Resistance of Acetylated Radiata Pine, European Beech, and MDF against Marine Borers at Three Italian Sites after Five Years Immersion

The aim of this research was to determine the resistance of acetylated wood against marine biodeterioration in use class 5 for use in temperate waters. The resistance of acetylated radiata pine (Pinus radiata D. Don) on solid and medium-density fiberboard (MDF) panels was compared with untreated wood of European species, such as European beech (Fagus sylvatica L.), sweet chestnut (Castanea sativa Mill.), European oak (Quercus robur L.), and marine plywood. As a reference control, untreated Scots pine (Pinus sylvestris L.) sapwood was used. The field tests were carried out in accordance with EN 275, and started in April 2015. The three Italian exposure sites were Marine of Scarlino private harbor, Port of Genoa, and the Venice Lagoon. Final evaluation in 2021 showed a greater resistance to marine borers of acetylated wood, radiata pine, and beech and MDF panels. However, the untreated European species showed low resistance against marine organisms, with complete decay after the first year of exposure.

Research on Medium density fiberboard (MDF) behavior against screw axial withdrawal: Impact of density and operational variables

Screw joint is a prevalent connection method in furniture, buildings, and structures, which plays an essential role in the integrity and durability of a wooden structure. Considering such benefits, the impact of core and face layers density, screw direction, pilot hole diameter, screw type, and water immersion on screw axial withdrawal resistance of medium density fiberboard (MDF) were investigated in this paper. The results showed that screw withdrawal resistance (SWR) of MDF panels in surface and edge directions were raised as density increased. The surface SWR was found to be higher than the corresponding ones in the edge direction. Besides, fine thread drywall displayed higher SWR than coarse thread drywall in both directions, due to more thread embedded. Results revealed that SWR was more affected by pilot hole diameter than panel density. Moreover, the best SWR was observed when the pilot hole was set close to the root diameter of the screw. The treatment of water soaking of MDF samples for 2 h negatively affected the SWR. Therefore, the edge SWR was more affected by water immersion. In addition, failure modes of screw withdrawal included sheet-shaped fracture of face layer along with protrusion of core fibers by pulling out the screw from surface and edge directions, respectively. This study suggests that a reliable connection can be made by selecting the proper screw and adjusting an accurate pilot hole even in a lighter product that is installed in humid conditions.

Influence of Pressing Schedule and Adhesive Content on the Rheological Behavior of Wood Fiber-Furnish Mats.

In this study, for a better understanding of the hot-pressing process, the influence of adhesive content (AC) on various features of a typical pressing schedule for medium-density fiberboard (MDF) production, including fiber mat compressibility, heat transfer during hot-pressing, density profile and board properties, were evaluated. It was found that increasing the AC (urea formaldehyde) leads to faster heat transfer towards the mat’s central plane, mainly due to higher heat release from the adhesive polycondensation reaction. Moreover, the results indicate that the time needed to reach the critical mark of 100 °C in the central plane of the mat depends on the duration of the first densification level (FD). Importantly, the pressure peaks (pmax and p2nd) needed for mat densification are significantly reduced when increasing the AC, which might be attributed to the slippery effect created by the adhesive on the fiber surfaces. The duration of the FD also showed obvious effects on the intermediate density maxima (ρinter) and the core layer density (ρcore). In general, the physical and mechanical properties of MDF panels are significantly impacted by the pressing schedule and AC. All in all, the results of this study are valuable information for refining existing rheological models to improve their accuracy and their ability to simulate the vertical density profile during industrial production.

Use of Agave durangensis Bagasse Fibers in the Production of Wood-Based Medium Density Fiberboard (MDF)

There is an increasing interest in using non-wood lignocellulosic materials for the production of wood-based medium density fiberboard (MDF). Agave durangensis Gentry bagasse is a waste product produced in large quantities in the mezcal industry. This study evaluated the incorporation of A. durangensis bagasse fibers (ADBF) to elaborate MDF wood-based panels. Three types of panels with different ratios (wood fibers: bagasse fibers) were investigated. The ratios evaluated were 100:0, 90:10, and 70:30. The density profiles, water absorption, and thickness swell of the panels were determined, as well as the modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB), according to the ASTM D1037-06a standard. The results were compared to the ANSI A208.2-2016 standard. The effect of the addition of ADBF on the properties of the panels was analyzed. Density profiles were comparable among the three types of panels, while water absorption, thickness swelling, MOE, MOR, and IB were similar between panels with ratios of 100:0 and 90:10. Panels with 10% and 30% of ADBF meet the minimum ANSI requirements for quality grade 115. It is feasible to use up to 30% of ADBF in the manufacture of wood-based MDF panels.

Medium density fiberboard (MDF) with efficient electromagnetic shielding: Preparation and evaluation

Carbon fiber (CF)-filled fiberboard specimens for electromagnetic (EM) shielding applications were produced in this study by mixing CF with wood fiber (WF). The aim of this work was to study the panel properties with different loadings (1%, 2%, 3%, 5%, and 10%) of CF. The mechanical, physical, and electromagnetic interference (EMI) shielding properties of the produced medium density fiberboard (MDF) were analyzed. The shielding effectiveness (SE) of the CF1 sample was 23.5 dB to 35.0 dB in the frequency range of 8.2 GHz to 12.4 GHz. The maximum SE of 64 GHz to 76 dB was obtained for the CF10 sample. The investigation of the mechanical properties of MDF panel indicated that the modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding (IB) of the composite panels were less than those of the control panel. The MOR, MOE, IB, thickness swelling (TS), and water absorption (WA) of the panel with 1% CF (CF1) were 24.7 MPa, 2,510 MPa, 0.69 MPa, 14.5%, and 52.3% respectively. Generally, the MDF panels with 1% CF exhibited a greater ability for EM shielding applications because of their acceptable properties according to the EN 622-5 (2019) standard and appropriate EM shielding of at least 20 dB.

Influence of wood leachate industrial waste as a novel catalyst for the synthesis of UF resins and MDF bonded with them

MDF (Medium Density Fiberboard) production processes produce a large amount of wood leachate as a hazardous waste. Wood leachate is a lignin-based waste material from the MDF production industry. It constitutes a potential environmental problem if discarded by penetrating into groundwater aquifers. Currently, there is no viable way for industrial MDF leachate waste to be transformed into environmentally friendly high value materials. The aim of this work was to present for the first time a novel approach which was successfully developed for the recovery of wood leachate industrial waste as a catalyst for the synthesis of UF adhesives for MDF panels. The leachates were examined by FTIR, 13 C NMR, and DSC as well as by evaluating the properties of fiberboards bonded with liquid UF resins. In addition, the other aim of this work was to capture the free formaldehyde gas emitted by MDF panels. It was of interest determine whether an MDF bonded panel prepared with a UF resin catalyzed by the wood leachate would exhibit lower formaldehyde emissions and the lowest thickness swelling, while still presenting a relatively good performance. The direct reuse of the fiberboard industrial leachate in the experiments demonstrated that the preparation method of the UF bonded fiberboard was environmentally friendly and sustainable. Therefore, this work arrived at some interesting conclusions that may be used as a base for future work on the recycling and reuse of MDF waste.

Reducing free formaldehyde emission, improvement of thickness swelling and increasing storage stability of novel medium density fiberboard by urea-formaldehyde adhesive modified by phenol derivatives

Notwithstanding the enormous benefits of medium density fiberboard, free formaldehyde emission and low water resistance are the significant disadvantages to reducing their application. In this research, phenolic compounds such as phenol, 1,2,4-trihydroxy benzene (hydroxyquinol), and 4-tert-butyl catechol in various amounts were added to an industrial-grade liquid urea-formaldehyde polymer in an attempt to alleviate these defects. Medium density fiberboard panels were manufactured from the modified urea-formaldehyde resins. The panels' physical and mechanical properties, such as thickness swelling, water absorption, formaldehyde emission, modulus of rupture, modulus of elasticity, and internal bond strength were then investigated. The results showed that the free formaldehyde emission contents for the modified composite panels ranged from 25.4% to 50.1% lower than for the unmodified panel. Also, the lowest and highest levels of thickness swelling occurred with the medium density fiberboard panels bonded with UF-P1 and the unmodified urea-formaldehyde, respectively. The results clearly showed that the urea-formaldehyde polymer's storage capacity increased substantially with the addition of phenolic derivatives. The produced novel medium density fiberboard results can be said to substantially lower environmental and health hazards associated with these materials and have a beneficial effect on the water transport characteristics exhibited by these materials. Consequently, this research may play a role as a useful stepping-stone for solving the fundamental problems of medium density fiberboard production industries.

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.