Urea-formaldehyde Resin Content Research Articles

DETERMINATION OF UREA-FORMALDEHYDE RESIN CONTENT IN POPLAR FIBER BASED ON HYPERSPECTRAL TECHNIQUES

In this experiment, poplar fibers containing 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25% and 30% of urea-formaldehyde resin were prepared. A model for the detection of urea-formaldehyde resin content in poplar fibers was established by the hyperspectral near-infrared imaging system combined with relevant algorithms. The spectral images of poplar fibers containing different contents of urea-formaldehyde (UF) resin were measured separately using hyperspectral imager. The results of four preprocessing methods, namely mean centering (MC), multiple scattering correction (MSC), standard normal variables (SNV) and first-order derivative (1-Der) were analyzed, and the optimal preprocessing method was selected as SNV. The band combinations with the highest correlation with the urea-formaldehyde resin content were compared and analyzed with the full-band model to establish the partial least squares regression (PLSR) model. The experimental results show that the hyperspectral imaging system combined with the corresponding algorithm can achieve rapid detection of UF resin content in poplar fibers, and the results of this study provide technical support and theoretical reference for determination of resin content in ultra-thin fiberboard production. The method is an innovative model for the determination of UF resin in wood fibers.

Rapid determination of urea formaldehyde resin content in wood fiber mat using near-infrared spectroscopy

Monitoring the process is crucial for ensuring high quality in wood-based panel production. Interest in the distribution of resin in fibers and particles has increased during the last couple of decades. This study considered the potential to determine urea formaldehyde (UF) resin content in fiber mat using near-infrared (NIR) spectroscopy. Fiber mats with various resin contents were investigated with NIR combined with the partial least squares (PLS) regression and root mean square error of calibration and validation (RMSECV). The external factors, such as the distance between the fiber optic probe and the sample surface and light sources, were also evaluated. The results showed that this technique can sufficiently determine the resin content in the resinous fiber mat with accuracy of up to 95%. The light sources and the distances from the probe to the surface did not significantly influence the discrimination and prediction of resin content.

Physical and Mechanical Properties of Particleboard Produced with Addition of Walnut (Juglans regia L.) Wood Residues.

The depletion of natural resources and increased demand for wood and wood-based materials have directed researchers and the industry towards alternative raw materials for composite manufacturing, such as agricultural waste and wood residues as substitutes of traditional wood. The potential of reusing walnut (Juglans regia L.) wood residues as an alternative raw material in particleboard manufacturing is investigated in this work. Three-layer particleboard was manufactured in the laboratory with a thickness of 16 mm, target density of 650 kg∙m−3 and three different levels (0%, 25% and 50%) of walnut wood particles, bonded with urea-formaldehyde (UF) resin. The physical properties (thickness swelling after 24 h) and mechanical properties (bending strength, modulus of elasticity and internal bond strength) were evaluated in accordance with the European standards. The effect of UF resin content and nominal applied pressure on the properties of the particleboard was also investigated. Markedly, the laboratory panels, manufactured with 50% walnut wood residues, exhibited flexural properties and internal bond strength, fulfilling the European standard requirements to particleboards used in load-bearing applications. However, none of the boards met the technical standard requirements for thickness swelling (24 h). Conclusively, walnut wood residues as a waste or by-product of the wood-processing industry can be efficiently utilized in the production of particleboard in terms of enhancing its mechanical properties.

Effects of Planting Density of Rubber Tree Clone (RRIM 2020 Clone and RRIM 2025 Clone) Wood to Particleboard Properties

The depletion of log resources encourages research into alternative ways to sustain the wood supply. Therefore, the 4-year-old Rubber Research Institute of Malaysia (RRIM) clones series, RRIM 2020 and RRIM 2025, were chosen as potential raw materials for particleboard in this study. The purpose of this study was to assess the effects of planting density and rubber tree clones on the mechanical and physical properties of single-layer particleboard. The planting densities used were low, moderate-low, moderate-high, and high, representing 500, 1000, 1500, and 2000 trees/ha, respectively. Prior to manufacturing, the RRIM 2000 series clone trees were harvested, cut, chipped, flaked, and screened. The mechanical and physical properties were evaluated in accordance with the Japanese Industrial Standard (JIS A 5908-2003). The findings revealed that both planting density and clone had a signifi- cant impact on the mechanical and physical properties of particleboard with a thickness of 10 mm and a density of 700 kg/m3 . RRIM 2020 specimens with low planting density had superior modulus of elasticity (MOE), modulus of rupture (MOR), and internal bonding (IB) values of 2415, 19, and 1.7 MPa, respectively. Furthermore, moderate-low planting density demonstrated the lowest thickness swelling (TS) and water absorption (WA) values and was comparable to control particleboard from commercial clone Prang Besar (PB), PB260. In terms of rubber clones, RRIM 2020 particleboard met the minimum requirements of the JIS standard for mechanical properties and outperformed RRIM 2025. This study recommended a low planting density of 500 trees/ha and the RRIM 2020 clone as a suitable raw material for particleboard manufacturing with a ten percent urea formaldehyde resin content.

Properties of High-Density Fiberboard Bonded with Urea-Formaldehyde Resin and Ammonium Lignosulfonate as a Bio-Based Additive.

The potential of ammonium lignosulfonate (ALS) as an eco-friendly additive to urea–formaldehyde (UF) resin for manufacturing high-density fiberboard (HDF) panels with acceptable properties and low free formaldehyde emission was investigated in this work. The HDF panels were manufactured in the laboratory with very low UF resin content (4%) and ALS addition levels varying from 4% to 8% based on the mass of the dry wood fibers. The press factor applied was 15 s·mm−1. The physical properties (water absorption and thickness swelling), mechanical properties (bending strength, modulus of elasticity, and internal bond strength), and free formaldehyde emission were evaluated in accordance with the European standards. In general, the developed HDF panels exhibited acceptable physical and mechanical properties, fulfilling the standard requirements for HDF panels for use in load-bearing applications. Markedly, the laboratory-produced panels had low free formaldehyde emission ranging from 2.0 to 1.4 mg/100 g, thus fulfilling the requirements of the E0 and super E0 emission grades and confirming the positive effect of ALS as a formaldehyde scavenger. The thermal analyses performed, i.e., differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the main findings of the research. It was concluded that ALS as a bio-based, formaldehyde-free adhesive can be efficiently utilized as an eco-friendly additive to UF adhesive formulations for manufacturing wood-based panels under industrial conditions.

An innovative IoT-oriented prototype platform for the management and valorisation of the organic fraction of municipal solid waste

Abstract This research paper is focused on the upscaling of previous studies of authors group about the stabilization, inertization and valorisation of the Organic Fraction of Municipal Solid Waste (OFMSW). The developed process first involves the development of an original process in order to transform the organic waste into an inert and sterilized material and, successive incorporation of the treated-OFMSW into a catalysed water soluble Urea Formaldehyde (UF) based resin. In particular, in this research work we report on the design and realization of a prototype platform able to produce inertized and valorised panels, starting from OFMSW. The platform is managed by Arduino-based electronic sections for controlling process parameters and integrated with user’s recognition and product traceability system based on Radio Frequency Identification (RFID) technology. Several panels were produced, by transforming different amounts and typology of OFMSW, in order to select the best composition, as a compromise between the production of panels with adequate mechanical properties and the usage of the lowest UF resin content. Mechanical and thermal characterization of the realized products was performed looking at potential applications of the panel. Finally, the RFID-based traceability system, managed by a properly developed software platform, allows to identify and store in the database the enabled users which give the OFMSW in the machinery and to track the produced panels or bricks, by using suitable wide-band low-cost passive UHF tags, thereby ensuring targeted and optimal management of the re-use or storage of the valorised products. In particular, the proposed system includes an innovative ICT part that uses UHF RFID technology, low-cost sensors and a Cloud platform capable to manage all collected data related to both disposed waste and bricks produced by transformation procedure.

EFFECTS OF NANO-SILANE ON THE PHYSICAL AND MECHANICAL PROPERTIES OF ORIENTED STRAND LUMBER (OSL)

Cette étude s’est penchée sur les effets de la teneur en résine et en composés de nano-silane (NS) sur les panneaux struc- turaux orientés (OSB), un important pro- duit en bois reconstitué. Des panneaux OSB ont été fabriqués avec de la résine d’urée-formaldéhyde (UF) à 8 % et à 10 % (sur poids sec des panneaux), avec appli- cation de NS à deux teneurs en fonction de la teneur en résine UF. Nos résultats montrent que les traitements aux deux teneurs différentes en résine donnent des valeurs très proches pour les modules de rupture et d’élasticité, la flexion au choc et la résistance à la traction. Cela indique que la compacité élevée des lamelles de la matrice OSB est le facteur déterminant des propriétés mécaniques globales des panneaux composites. L’interaction entre NS et résine UF affaiblit significativement ces propriétés dans la plupart des cas de traitement à 10 % NS, alors que le dosage de NS à 20 % est suffisant pour contri- buer activement au processus de collage des lamelles et compense les pertes en partie. L’analyse par cluster indique que les propriétés mécaniques sont générale- ment davantage fonction de la compacité de la matrice composite que de la teneur en résine. Dès lors, l’étude conclut que le NS n’est pas à recommander à l’industrie en raison de ses effets négatifs sur la plu- part des propriétés physiques et méca- niques des panneaux OSB.

Effects of Nano-Wollastonite on Screw Withdrawal Capacity of Oriented Strand Lumber

The effect of changes of urea-formaldehyde resin content and nanowollastonite content on the withdrawal capacities of sheet metal screws and medium density fiberboard screws from the edge, face, and end surfaces of oriented strand lumber were investigated. The panels were produced with two urea-formaldehyde resin contents (8% and 10%), and two nano-wollastonite contents (10% and 20%). Specimens were prepared and tested according to ASTM standard D 1761-88. Sheet metal screws had a higher withdrawal capacity than medium density fiberboard screws. Withdrawal capacity in the face and edge directions were significantly higher than in the end direction. Changes in urea-formaldehyde resin content had no effect on screw withdrawal capacity in any of the three directions, implying that compaction in the composite panels had higher impact on screw withdrawal strength in comparison to the increase in resincontent from 8% to 10%. However, addition of NW resulted in a decrease in withdrawal capacity values at both resin levels in all directions.

Acoustical properties of plywood/waste tire rubber composite panels

Abstract This paper presents the acoustical performance of plywood/waste tire rubber (PWTR) composite panels. Beech ( Fagus orientalis ) and alder ( Alnus glutinosa ) veneers having 1.8 mm thickness were used in the preparation of panels. The wood layers were bonded using commercial urea–formaldehyde (UF) resin, and methylene diphenyl diisocyanate (MDI) was used to form the rubber layers and bond them to the wood veneers. The four variable parameters considered were WTR contents (430 and 720 g), resin contents (120 and 160 g/m 2 ), hot pressing (one- and two-stage), and arrangements of veneer layers. Free vibration based on a free-free bar method was used to evaluate the specific modulus of elasticity, damping factor, acoustic coefficient, and acoustic converting efficiency of the experimental panels. The test results indicated that the sound insulation property of PWTR was highly dependent on the variable parameters. We found that the damping factor and acoustical coefficient of PWTR are significantly affected by the amount of WTR and UF resin content used in the composite. An increase in the usage of WTR and the dosage of UF adhesive considerably improved the soundproof property of the PWTR. An increase in the WTR content in plywood improved the composite’s damping factor. Finally, the results demonstrated that the PWTR composite has potential as an interior building material to absorb sound but requires full-scale testing on site. This approach offers an environmental friendly solution to the ongoing problem of WTR.

Oxidative Activation of Bagasse Fibers Surfaces in Medium Density Fiberboard Manufacturing

This study presents the investigation of the effects of oxidant type (nitric acid and potassium dichromate), oxidant content (three different levels as 2, 4, and 6 percent) and ureaformaldehyde (UF) resin percentage (two levels as 5 and 7 percent) on mechanical and physical properties of interior grade medium density fiberboard made from bagasse fibers. Some panel properties were studied, such as modulus of rupture (MOR) and modulus of elasticity (MOE) in bending, compression-shear strength (C.S sth.), water absorption (WA) and thickness swelling (TS) after 2and 24-hour immersion in cold water. In addition, the results indicated the best values for WA and TS after 2and 24-hour immersion, and C.S. sth. was discerned at 7 percent UF resin content, together with 6 percent nitric acid. Furthermore, the greatest values for MOR and MOE were related to 7 percent UF resin content together with 4 percent nitric acid.

FULL RECOVERY OF ARUNDO DONAX PARTICLEBOARD FROM SWELLING TEST WITHOUT WATERPROOFING ADDITIVES

This paper presents the development of particleboard based on common reed, reproducing the industry standard manufacturing process applied to wood chipboard. One of the main properties of the resulting board was its resistance to water, due to the hydrophobic properties of the common reed, despite there being no incorporation of melamine or any other waterproofing additive. The boards that were developed were analyzed using 2 mm and 4 mm sieves for fibre selection, a manufacturing pressure of 3 N/mm2 and 25 N/mm2, and a volume of urea formaldehyde resin content ranging from 5.2% to 13% (8 to 20% liquid format). Standard destructive tests were performed. It was found that under certain applied conditions, namely high pressure and adequate resin proportion (a pressure of over 3 N/mm2 and over 15% liquid resin), Arundo donax L. particleboard demonstrated full recovery from the swelling test. This finding highlights an unmatched property in terms of recovery from the swelling test of the designed board. This property confers a interesting property to be used in high humidity environments without the need for special resin or waterproofing process.

New composite grouting materials: Modified urea–formaldehyde resin with cement

A new composite two component grout comprised of modified urea–formaldehyde resin and cement was formulated to take account of the advantages and disadvantages of both the cement grout and the chemical grout. The new grout is designed for water blocking by reinforcing as well as seepage control by bore grouting. The A component consists of a modified urea–formaldehyde resin A component, some cement, and some water. The B component is an alkaline coagulant. An orthogonal test of four factors at three levels showed that gel time increased with increased water content and with urea–formaldehyde resin content. Gel time decreased at increased levels of alkaline coagulant. The A component of this new composite grout is stable over time. A mixed cross-over test showed that as the volume ratio of A to B increases the gel time falls at first but then increases. The solid strength decreases with increasing levels of the B component. The solid strength increases over time and becomes stable by the 28th day after mixing. The viscosity increases with increasing levels of resin A component. The increase is exponential and may be fit to: μ=8.162e0.0286x.

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

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

Potential of pulp and paper sludge as a formaldehyde scavenger agent in MDF resins

Abstract Sludge of pulp and paper mills have natural adhesive properties. The primary sludge (PS, contains fibers) and secondary sludge (SS, contains proteins) could also be suitable for manufacturing medium-density fiberboard (MDF). Protein in SS can react with formaldehyde (HCHO), and as an additive in urea-formaldehyde (UF) resins it can reduce formaldehyde emission. Thus, SS was investigated in the present study. PS and SS were collected from two mills and characterized in terms of chemical composition, fiber length distribution, pH, and buffering capacity. MDF samples were processed according to an experimental design, in which UF resin content was reduced from 12% to 8% and replaced by SS in the range of 5%–15%. Gel time measurement showed high SS reactivity with UF resin. The SS reduced HCHO emissions by up to 68% compared to control panels, without compromising internal bond strength. The bonding effect of SS was lower than expected due to the high pH, thus the buffering capacity reduced UF performance. Moreover, sludge reduced bending performance. Dimensional stability was the greatest disadvantage of sludge panels.

Low resin medium density fiberboard made from chemical activated hardwoods fibers

This study was conducted to determine properties of medium density fiberboards (MDF) made from treated hardwoods fiber furnishes containing different amounts of two oxidizers, and the addition of limited amounts of synthetic resin. The effects of urea–formaldehyde (UF) resin content (two levels as 5 and 7%), oxidizer type (nitric acid and potassium dichromate), and oxidizer percent (three different levels as 4, 6, and 8%) on some static mechanical and physical properties of dry process interior grade MDF such as modulus of rupture (MOR), and modulus of elasticity (MOE) in bending in dry condition, compression-shear strength (CSsth), water absorption (WA) and thickness swelling (TS) after 2- and 24-h soaking in cold water were investigated. Thirty six oxidative activated laboratory MDF panels were tested. Test results showed that increasing resin content significantly improved all physical and mechanical properties of treated MDF boards. Nitric acid had better mechanical and physical properties than potassium dichromate. Increasing oxidizer percent improved the physical and mechanical properties of MDF boards. Finally, three-way interaction of variables showed the best values for MOR, MOE and CSsth and WA and TS after 2- and 24-h soaking were discerned for T6 treatment, i.e. the combination of 7% UF resin content together with 8% nitric acid. The properties for T6 met the mechanical strength requirements of ANSI standard (ANSI A208. 2-2002) for 120-grade MDF.

Use of Guadua angustifolia stems in the particleboard production

The industry agglomerated panels incorporated into its manufacturing process tree species of both conifers and hardwoods, today, many companies operate at half of its production capacity for the continued lack of raw material due to depletion of main species or operational restriction. The main objective of this paper was to determine the technological feasibility of Guadua angustifolia as raw material for the production of particleboard at two levels of theoretical density (nominal) of 600 kg/m3 and 800 kg/m3 with urea formaldehyde resin content of 12%. The physical and mechanical properties of the boards were determined according to German Norms DIN 52361, 52362, 52364 and 52365, and Venezuelan Covenin Norm 847-91 for flat platen-pressed particleboard. The mechanical properties were static bending (MOR), and tension perpendicular to the board surface (internal adhesion); the physical properties were water absorption and thickness variation by water soaking absorption tests at 2 and 24 hours. The results of this study indicated that the boards manufactured with this species showed values in the physical and mechanical properties that comply with the ones specified by the norms. The presence of the stem external cuticle negatively influenced the water absorption and the tension perpendicular to the board surface of the boards with a density of 600 kg/m3.

Propriedades físicas e mecânicas de painéis MDF de diferentes massas específicas e teores de resina.

Painéis MDF foram preparados, em escala laboratorial, com base em fibras de Pinus spp. com diferentes teores de resina (6, 8, 10, 12 e 14%) e massas específicas (600 a 800 kg/m3) com o objetivo de avaliar suas propriedades físicas e mecânicas. Os efeitos da massa específica e do teor de resina, bem como sua interação foram avaliados tendo como base as propriedades físicas e mecânicas dos painéis MDF. As propriedades mecânicas avaliadas foram módulo de elasticidade e de ruptura e adesão interna, enquanto as propriedades físicas foram absorção de água e inchamento em espessura. Todas as variáveis se relacionaram significativamente com os fatores massa específica e teor de resina e a interação foi significativa a 1% apenas no inchamento em espessura. Foram propostos modelos para avaliar as propriedades físicas e mecânicas em razão da massa específica e do teor de resina.