Medium Density Fiberboard Production Research Articles

Physical and Mechanical Properties of Fiberboard Made of MDF Residues and Phase Change Materials

The wood-based panel industry is experiencing an excessive accumulation of solid residues from the production of medium-density fiberboard (MDF) panels and moldings. It is possible to create new MDF products with acceptable physical and mechanical properties by revaluing MDF residues. Additionally, those products’ thermal properties can be improved by incorporating phase change materials (PCMs). This study aims to develop a wood-based fiberboard made of MDF residues, capable of storing thermal energy. Two types of PCMs (liquid and microencapsulated), two PCM ratios (2% and 6%), and two types of adhesives (urea-formaldehyde and phenol-formaldehyde) were used to produce eight different types of panels. The vertical density profile, thickness swelling, water absorption, internal bond (IB), and static bending properties—modulus of elasticity (MOE) and modulus of rupture (MOR)—were determined for each panel type. The specific heat of the panels was also determined. The results show the panels’ densities were greater than 700 kg/m3. Thickness swelling in water improved by 23% compared to the reference value of the control panel PCMs after PCM incorporation. The highest IB value was 1.30 MPa, which is almost three times the minimum required by regulation standards. The incorporation of PCMs reduced the panels’ bending properties compared to the properties of the control panels. Even though the values obtained are sufficient to comply with the minimum values set out in ANSI standard A208.2 with an MOE value of 2072.4 MPa and the values obtained are sufficient to comply with the minimum standards with an MOE value of 2072.4 MPa and an MOR value of 16.4 MPa, when microencapsulated PCM is used, the specific heat of the panels is increased by more than 100% over that of the control panels. This study developed fiberboards with adequate physical and mechanical properties and capable of storing thermal energy.

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.

Synthesis of iso-amyl ester rosin and its evaluation as an alternative to paraffin in medium density fiberboard production

Iso-amyl ester rosin was synthesized and investigated for its potential utilization in medium density fiberboard (MDF) production. The isoamyl alcohol, the main starting material for the synthesis of isoamyl ester rosin, was obtained through the fractional distillation of fusel oil, a byproduct of bioethanol production. The optimum condition for the iso-amyl ester rosin synthesis was determined as: rosin (165 mmol), isoamyl alcohol (413 mmol), P-TSA/rosin 1.5% (w/w), and commercial additive/rosin 0.15% (w/w). The esterification reaction was followed by FT-IR and mass analysis. For MDF production, a water-repellent material, commercial paraffin (1.5% w/w relative to the dry fiber weight), iso-amyl ester rosin (1.5% and 2.0%; w/w), and unmodified rosin (1.5% and 2.0% w/w) were separately used. In addition, fresh wood fibers, 10% w/w urea formaldehyde (UF) adhesive (relative to the total dry fiber weight), and a 25% aqueous solution of ammonium chloride (as the hardening agent for the UF adhesive, at 0.5% w/w based on the solid adhesive content) were used. MDFs underwent various physical and mechanical tests. Isoamyl ester rosin showed promising results based on the analysis. The results showed that the isoamyl ester rosin can be considered as an alternative to paraffin in sustainable and environmentally friendly MDF production.

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.

Impact of moisture content, closing speed, and pressurizing speed on the performance of medium density fiberboard (MDF)

The purpose of this research is to investigate the impact of moisture content, closing speed, and pressurizing speed of hot press on the density, uniformity of density distribution, and properties of Medium Density Fiberboard (MDF) products. Moisture content affects the plasticity, heat conductivity, and hydrolysis reaction of the fiber and appropriate moisture content ensures the quality of the board. Excessive moisture content can lead to defects such as pollution and bubbles on the surface of the board. Closing time and pressurizing speed affect the nature, quality, and section structure of the MDF. The section density of the board varies with the closing time, and the product properties, especially the strength differs largely. The pressurizing speed influences the density distribution and board properties. Fast pressurizing speed results in high Modulus of Rupture (MoR) and low Internal Bonding (IB), while slow pressurizing speed leads to low MoR and high IB. Pre-plasticizing layer can improve the quality of MDF by increasing the density and hardness of the board surface. The findings provide guidance for optimizing the MDF production process and improving the quality of MDF products. Applying a fast pressurizing speed during the manufacturing process of MDF has resulted in a 15.7% increase in the MoR, which is a measure of the material’s ability to withstand stress before breaking as compared to using a slow pressurizing speed. Additionally, using a fast pressurizing speed has led to a reduction of 17.4% in the IB, which is a measure of the ability of the board to resist internal separation or delamination. Therefore, a fast pressurizing speed is more effective in improving the mechanical properties of MDF.

An Application of Six Sigma for Optimality of Medium Density Fiberboard Production

During the production process of MDF, there is a high level of internal bond (IB) variation. This results in the waste of out-of-standard IB values that account for 0.38 % with damage value over 1 million baht/year. The company required products with fewer volatile compounds from formaldehyde adhesives, focusing on reducing the amount of adhesive but still being strong according to IB-specification which will reduce the cost of production by about 20 − 30 million baht/year. The results of wood sampling and IB testing were divided into 6 areas, namely IB1-IB6. It was found that most of the data were symmetrical except for the IB5 data as the area where the most variation occurs. The distributions of the IB1 and IB6 data showed relatively low variability compared to data from other areas. IB1 - IB6 values were normal distribution, expect for IB5. Process capacity in IB2 was relatively high compared to IB from other areas. From the Correlation Matrix and Correlation Map, it was found that the variables that influenced the IB were Press Factor, % Dosing Glue, Heat Circuit1, Primary Circuit Intel and % Mc After Gluing. To conduct the experiment and find the best variable conditions by 25-2 - Factorial Design (Resolution: III). It was found that Glue = 7.4, Heat1 = 234.4, and Press = 6.5 would give IB = 0.88 which was closest to target (0.7). Glue = 7.1, Heat1 = 233.2, and Press = 6.48 would give IB = 1.15 which was the highest value. Results of production conditions at optimum or maximum that can be generalized from Rayleigh Method Dimensional Analysis was found that at the levels of 7.85, 254.28 and 257.70 of Glue, Heat1 and PrimCirIn, the target response (IB) was 0.7. and at the levels of 8.07, 233.35 and 281.60 of Glue, Heat1 and PrimCirIn resulted in a response value (IB) of 1.27.

Prediction of power consumption from real process data of an industrial wood chip refining plant

Improving the efficiency of production processes is fundamental to minimize their environmental impact and energy consumption. The pulp and paper industry is a highly energy-intensive one that urgently needs to become more efficient, especially in the refining phase. In this framework, the model identification of a wood chips refining process operating in closed loop, pertaining to the production of Medium Density Fiberboard (MDF), is presented here, aimed to provide a long-term prediction of power consumption. We perform the identification via multi-batch Simulation Error Minimization (SEM), employing real process data collected on a large-scale MDF production plant during operation, without using sophisticated models or ad-hoc experimental sessions. The derived model obtains extremely high accuracy on a validation dataset while being simple enough to be used efficiently for production planning optimization. Moreover, it allows us to derive further models to predict the wear of the refiner disc, to be accounted for in a plant optimization procedure as well.

Comparison of Water Resistance for Modified Medium-Density Fiberboard

Abstract Commercial medium-density fiberboard (MDF) products, specifically manufactured for water resistance, were evaluated over 8 days under three water exposure regimes: 90 percent relative humidity, one-sided water spray, and one-sided wet pad. A three-cycle wet-pad and drying exposure test was also performed. Rate of swelling, extent of swelling, and irreversible thickness swelling were determined. Acetylated MDF (AMDF) had the best overall performance, followed by steam-injection pressed MDF (SMDF) and polymeric methylene-diphenyl-diisocyanate–bonded moisture-resistant MDF. The fastest rate of thickness swell and linear expansion occurred with exposure to one-sided water spray and the slowest with 90 percent relative humidity exposure. While AMDF was clearly superior after 24-hour exposure, the other MDF products were nearly identical. Significant difference in thickness swell and water absorption between moisture-resistant MDF and SMDF developed after 24 hours. Regardless of the method of water exposure, the trend of best to worst MDF performance was the same.

Research on Failure Mechanism of Abrasive Belt and Effect on Sanding of Medium-Density Fiberboard (MDF)

Sanding is a very important process in MDF production. In this study, abrasive belts (P60 and P120) and MDF were used to conduct sanding experiments, and mass variation, surface morphology, and surface roughness of the abrasive belts were measured to analyze the failure process of the utilized abrasive belts. It is found that the mass of the abrasive belt mainly increased in the sanding process. The increase range of P60 is mainly within the scope of 0~0.02 g, while for P120, the mass change mostly fluctuates within 0~0.01 g. The surface roughness (Sa and Sku) of abrasive belts presents a down-and-up trend as sanding times increase, and Sa and Sku of P60 are both larger than those of P120. Wood fibers with adhesive blocked the space among grits and led to a “grits gathering” phenomenon. When the area of “grits gathering” is larger, it forms an abrasive belt “blocking”. Grit wear (dropping-off, fracture) and “blocking” constitute the two predominant patterns of the failure mechanism. This study is helpful to further improve wood-material-sanding theories, provide insights to investigate wear forms of other abrasive belts, and determine and extend the life of abrasive belts.

Potential use of metalworking fluid as surface additive for improving surface properties, technological properties, and formaldehyde emission of fiberboard

This study investigated the potential use of metalworking (cutting) fluid as an surface additive in the production of medium density fiberboard (MDF). The cutting fluid was sprayed on the mat surface of the fiberboard at different loading levels, of 3.5 g/m2, 7 g/m2, and 14 g/m2 (5 wt% or 10 wt% concentration levels) before the hot pressing. Some physical and mechanical properties of the resulting MDF specimens were carried out according to European standards. The bending strength and bending modulus, internal bond strength improved with the addition of the cutting fluid into the surface layers while the thickness swelling and water absorption decreased. This might be related to the fact that there was no hydrophobic chemical used in the production. The improvement in the adhesive bond between the fibers may be explained by the enhanced heat transfer from surface to the core layer of the MDF. The formaldehyde emission of the MDFs decreased with the incorporation of the cutting fluid. It was estimated that the crosslinking of the UF resin increased due to the higher thermal conductivity of the cutting fluid. The preliminary findings of the present study showed that the cutting fluid used in the metal industry could be efficiently used as surface additive in the production of the MDF.

Processing and Wood Factors Influence Medium Density Fiberboard Production from Young Eucalyptus grandis, E. amplifolia, Corymbia torelliana, and Cottonwood Grown in Florida USA

Fast growing Eucalyptus grandis W. Hill ex Maiden (EG), E. amplifolia Naudin (EA), Corymbia torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson (CT), and Populus deltoides W.Bartram ex Marshall (PD) may be deployed in Short Rotation Woody Crop (SRWC) systems in the lower Southeastern USA, especially in Florida. To evaluate these species for possible use as medium density fiberboard (MDF) and other composites, 2.5 m logs of three EG clones, three PD clones, six EA progenies, four CT trees, and one P. tremuloides Michx. (PT) tree from northern Wisconsin as a control were characterized for basic wood properties before being chipped, pulped, and pressed into MDF. The chips were thermomechanically pulped (TMP) for a two-phase study of the factors expected to influence suitability for MDF production: wood characteristics, refining system, resin system, and MDF formation. Phase I used TMP and 4% phenol-formaldehyde (PF) resin to produce 17 MDF species/genotype batches (S/GB). Thickness Swell (TS), Water Absorption (WA), Internal Bonding (IB), Modulus of Elasticity (MOE), and Modulus of Rupture (MOR) were evaluated to: (1) assess within species and within tree variation, (2) relate basic wood properties to MDF potential, and (3) examine repeatability of MDF-making. There was considerable variation among and within species, but only minor within tree variation. Six of the seventeen S/GBs had superior physical and mechanical MDF properties. In Phase II, two of the six better performing Phase I S/GBs were evaluated, along with three average Phase I S/GBs. Phase II compared the effects on IB from using tube and drum blenders for resin application, the influence of using unscreened versus screened fibers, and the differences of using PF resin at 4% or 6% versus urea-formaldehyde (UF) resin at 8% or 12%. Overall, genetic variation among species, and particularly within these species, affected their potential for commercial MDF. Log specific gravity (SG), fines, MDF SG, and fiber length influenced MDF properties, as did refining and MDF-processing variables. Further study of specific processing requirements can optimize the potential of young EG, EA, PD, and CT genotypes for MDF and other composites.

Enzymatic Oxidation of Ca-Lignosulfonate and Kraft Lignin in Different Lignin-Laccase-Mediator-Systems and MDF Production

Laccase-mediator-oxidized lignin offers replacement for conventional chemical binders to produce fiberboards. Compared to the previously reported laccase–mediator system (LMS), a lignin-laccase-mediator-system (LLMS) has an advantage in that it requires much shorter fiber-enzyme incubation time due to significantly increased redox reactions. However, the cost of regularly applying laccase on an industrial scale is currently too high. We have employed CcLcc5 from cultures of the basidiomycete Coprinopsis cinerea as a novel basi-laccase (a CAZy subfamily AA1_1 laccase) in medium-density fiberboard (MDF) production, in comparison to the commercial formulation Novozym 51003 with recombinantly produced asco-laccase MtL (a CAZy subfamily AA1_3 laccase-like multicopper oxidase from the ascomycete Myceliophthora thermophila). With the best-performing natural mediator 2,6-dimethoxyphenol (DMP), unpurified CcLcc5 was almost as good as formulated Novozym 51003 in increasing the molecular weight (MW) of the technical lignins tested, the hydrophilic high-MW Ca-lignosulfonate and the hydrophobic low-MW kraft lignin (Indulin AT). Oxygen consumption rates of the two distantly related, poorly conserved enzymes (31% sequence identity) with different mediators and lignosulfonate were also comparable, but Indulin AT significantly reduced the oxidative activity of Novozym 51003 unlike CcLcc5, regardless of the mediator used, either DMP or guaiacol. Oxygen uptake by both laccases was much faster with both technical lignins with DMP than with guaiacol. In case of lignosulfonate and DMP, 20–30 min of incubation was sufficient for full oxygen consumption, which fits in well in time with the usual binder application steps in industrial MDF production processes. LLMS-bonded MDF was thus produced on a pilot-plant scale with either crude CcLcc5 or Novozym 51003 at reduced enzyme levels of 5 kU/kg absolutely dry wood fiber with lignosulfonate and mediator DMP. Boards produced with CcLcc5 were comparably good as those made with Novozym 51003. Boards reached nearly standard specifications in internal bond strength (IB) and modulus of rupture (MOR), while thickness swelling (TS) was less good based on the hydrophilic character of lignosulfonate. LLMS-bonded MDF with Indulin AT and DMP performed better in TS but showed reduced IB and MOR values.

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.

Eucalyptus Bark as Source of Bio-oil or Phenolic Compounds

Background: Eucalyptus bark and scraps are generated in the production of mediumdensity fiberboard (MDF). An approach aiming to add value to such wastes was studied, following the concepts of circular economy and biomass cascade strategy. Bio-oil and phenolic resin were produced by pyrolysis from two types of biomass, Eucalyptus bark and MDF waste. As is well known, conventional phenolic resins are normally obtained from fossil resources. These products were obtained from the pyrolysis of two types of biomass to reduce environmental waste and dependence on petroleum-based products. Objective: The main objective of the present study was to produce phenolic resin from Eucalyptus wastes, aiming to reduce the fossil dependence on conventional resins used in the production line of MDF. Methods: Fast pyrolysis and slow pyrolysis were employed for bio-oil and phenolic resin production. The bio-oil and resins were characterized with standard lab analyses for their physicochemical properties, while their thermal properties were studied via thermogravimetric analysis (TGA). Results: The shear strength of the lap internal bonding of the phenolic resin binders with 19.8% of bio-oil was 2.09, 1.34, and 1.63 MPa under dry, boiler, and soaked conditions, respectively, which was acceptable for panel fabrication and can represent a significant saving in terms of fossil resins and cost reduction. Discussion: According to the results, 1 g medium fraction of bio-oils was equivalent to 1.35 g of conventional phenols, indicating those bio-oils as phenolic structures that could be used as binders. The bio-oil yields for bark and MDF were 40.9 and 25.1, respectively, which indicate a potential for replacing the conventional fossil-based phenolic resin. Conclusion: The results revealed the possibility of replacing conventional fossil-based chemicals with phenolic resin from renewable resources with similar overall properties, replacing about 1/3 of the conventional resin.

Effect of calcite addition on technical properties and reduction of formaldehyde emissions of medium density fiberboard

Physical, mechanical, and formaldehyde emission properties were studied for medium density fiberboard (MDF) produced with oak (75%) and pine (25%) fibers that had been mechanically refined in the presence of calcite particles. The calcite slurry was prepared at two levels of solids, 1.5% and 3% (10 and 20 kg·m-³). Chips were cooked for 4 min at 185 °C, under 8 bar vapor pressure in an Andritz defibrillator. 1.8% liquid paraffin, 0.72% ammonium sulphate solution, and 11% urea-formaldehyde were added by percentage based on oven-dried wood fibers in the blowline at the exit of the defibrator. The fibers were dried to 11% moisture content. MDF boards (2100 mm × 2800 mm × 18 mm) were created using a continuous hot-press process. The addition of calcite in the course of MDF production resulted in improved physical properties, such as thickness swelling (ThS 24 hours) and water absorption (WA 24 hours). MDF boards prepared with calcite exhibited higher internal bond (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Resistance to axial withdrawal of screw also was increased by addition of 3% calcite. In addition, the lowest levels of formaldehyde emission were observed for MDF prepared with calcite at the 3% level.

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.

The use of borax pentahydrate of inorganic filler in medium density fiberboard production

The aim of the study was the use of the inorganic borax pentahydrate mineral in medium density fiberboard production instead of biomass fiber and to specify the performance which physical, mechanical, combustion of produced boards. Chips used in manufacture were subjected to cooking for 4,5 minutes in Asplund defibrator at the vapor pressure of 7,6 kg/cm2 pressure and 190 oC temperature. 1,6 % paraffin according to based on oven-dried wood fibers was added to cooked chips before the fiber processing in segments of defibrillator section. 1 % ammonium sulphate according to based on oven-dried wood fibers were added to fiber in the bowline. Borax pentahydrate was prepared in a separate tank in order to use the production of medium density fiberboard medium density fiberboard. Borax pentahydrate inorganic mineral was mixed with urea-formaldehyde resin. Urea-formaldehyde glue was prepared as three different solutions including the borax pentahydrate as 3 % (20 kg), 6 % (40 kg) and 9 % (60 kg) respectively. Borax pentahydrate mixed fibers were dried to 12 % moisture. Mat was formed before prepress. Daily multi-press was manufactured 188 °C temperature and 32 kg/cm² pressure and 270 second pressing time. Manufactured boards size were 2100x4900x18 (mm). According to this work result, 3 % and 6 % rate borax pentahydrate added medium density fiberboard boards were measured more good physical and mechanical test results compare to control boards. 9 % borax pentahydrate added medium density fiberboard boards were shown incredibly superior performance at fire resistance

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

Calcium carbonate modified urea-formaldehyde resin adhesive for strength enhanced medium density fiberboard production.

This study investigated the improved properties of calcium carbonate (CaCO3) modified urea–formaldehyde (UF) resin adhesive for medium density fiberboard (MDF) production. The CaCO3 modified UF resins were prepared by adding different proportions of CaCO3 to a low molar ratio UF resin at the initial stage of a typical synthetic process of the resin. The physicochemical properties of the resins were measured. The mechanical and environmental performances of the resin-bonded MDF panels were tested. The results show that the viscosity and free formaldehyde content of UF resins with or without CaCO3 modification were not significantly different. The solid content of the CaCO3 modified UF resin was significantly lower than that of the control group. In addition, the measured gel time of the CaCO3 modified UF resin was 111–149 s, which was longer than that of the control resin (82 s). The gel time was further extended with the increase of the CaCO3 content in the UF resin. The chemical group and crystal structure of UF resins with or without the modification of CaCO3 were not significantly different. The internal bonding (IB) strength of the MDF panels significantly increased from 0.75 MPa to 0.97 MPa when the UF resin was modified with 2% of CaCO3. This study provides scientific support for the preparation of inorganic mineral modified UF resins for strength enhanced wood-based panel manufacturing.