Commercial Urea Formaldehyde Research Articles

Reduction of Formaldehyde Emission from Particleboard by Phenolated Kraft Lignin

The aim of this study was the reduction of formaldehyde emission from particleboard by phenolated Kraft lignin. For this purpose, the lignin was extracted from black liquor and then modified by phenolation. During the urea formaldehyde (UF) resin synthesis different proportions of unmodified and phenolated Kraft lignins (10%, 15%, and 20%) were added at pH = 7 instead of the second urea. Physicochemical properties and structural changes of resins so prepared, as well as the internal bond (IB) strength and formaldehyde emission associated with the panels bonded with them were measured according to standard methods. The Fourier transform infrared (FTIR) analysis of lignin indicated that the content of O–H bonds increased in phenolated lignin while the aliphatic ethers C–O bonds decreased markedly in the modified lignin. Since both synthesis of UF resins and lignin phenolation are carried out under acid conditions, phenolation is an interesting way of modifying lignin for use in wood adhesive. The panels bonded with these resins showed significantly lower formaldehyde emission compared to commercial UF adhesives. The UF resin with 20% phenolated lignin exhibited less formaldehyde release without significant differences in internal bond strength and physicochemical properties compared to an unmodified UF resin. XRD analysis results indicated that addition of phenolated lignin decreased the crystallinity of the hardened UF resins.

Suitability of sorghum stalk fibers for production of particleboard.

The aim of this study was to investigate the suitability of sorghum (Sorghum bicolor) stalk (SS) as a promising raw material for particleboard manufacturing. The SS particles and industrial hardwood particles in various proportions were used as the raw materials for the surface and core layers of the three-layer particleboards. Commercial urea formaldehyde (UF) adhesive was used as a binder. Morphological and chemical characteristics of the SS were evaluated. Effects of five variable parameters on the physical (thickness swelling (TS), water absorption (WA)), and mechanical (modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB)) properties of the particleboards were determined. Other parameters such as type of resin (UF), hardener content (1%), type of hardener (NH4Cl), press closing time (5 mm/s), board density (0.70 g/cm(3)), and press pressure (30 kg/m(2)) were held constant. Fractional factorial was used to find the optimum condition for the studied variable parameters. The morphological results showed that SS had comparable fiber length with softwoods and fiber width and wall thickness values greater than the hardwood of common forest species. They had higher hot-water solubility values, lignin and ash contents than those of the other woody materials. The experimental results showed that increasing of SS particles usage in the surface layer significantly affects the board properties. Containing 50 wt% SS particles in the surface, the MOE and MOR values exceed the minimum requirements of the European norms (EN) standards, for general purposes. All of the particleboards produced from SS had IB higher than the EN standard requirement. The presence of SS in the particleboards resulted in higher WA and TS values. All the mechanical properties of the boards decreased when the press temperature was increased from 160 to 180°C. Finally, it can be stated that SS has enough potential as a supplement fibrous material, in combination with industrial hardwood particles, for particleboard manufacturing and indoor applications.

Improving urea formaldehyde resin properties by glyoxalated soda bagasse lignin

The aim of this research was a reduction of formaldehyde emission and the improvement of the water resistance of urea formaldehyde (UF) resins by incorporating glyoxalated soda bagasse lignin. For this purpose, various contents of unmodified and glyoxalated lignins (10, 15 and 20 %) were added at pH = 7 instead of second urea during the UF resin synthesis. The properties of the resins as well as water absorption, shear strength, and formaldehyde emission of plywood panels made with these adhesives were measured. Among all the resins synthesized, the resin yielding the best results (based on formaldehyde emission and gelation time as well as water absorption, mechanical strength, and formaldehyde content of the associated panels) was selected, and its properties were further analyzed by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectrometry (FTIR), and X-ray Diffractometry (XRD). The lignin based resins yielded good shear strength of the plywood panels, passing comfortably relevant international standard specifications; the panels also showed lower formaldehyde emission and water absorption when compared to commercial UF adhesives. Based on these findings, it was attempted to improve the performance of soda bagasse lignin in UF resins by glyoxalation. The UF resin containing 15 % glyoxalated lignin (GLUF15) still exhibited less water absorption and formaldehyde release without significant differences in shear strength and physicochemical properties compared to the UF resin control. DSC analysis indicated that in comparison to UF resin the curing process of GLUF resin shifted to lower temperatures. According to the FTIR spectra, by addition of lignin the proportion of C–N bond in methylene linkages decreases when urea is partly replaced by lignin or glyoxalated lignin. XRD analysis indicated that the crystallinity of the UF resins decreased with addition of glyoxalated lignin.

Optimising the process for production of high performance bagasse-based composites from rice bran-UF adhesive system

Purpose – The purpose of this paper is to prepare high-performance agro-based composites from the non-toxic rice bran-urea-formaldehyde (RB-UF) adhesive system. Investigations have continued for production high performance agro-based composites using environmentally acceptable approaches. The utilisation of such system with the available used local agro-based wood products (sugar-cane bagasse, SCB) adds economic value and helps reducing the environmental impact of commercial urea-formaldehyde (UF) adhesive, and most importantly, provides a potentially inexpensive alternative to the existing commercial artificial wood-panel mills. Design/methodology/approach – Optimising the process for incorporating the RB in UF, as wood adhesive for binding the bagasse fibres, was carried out, by partially replacing commercial UF by denaturalised RB in slurry (wet) and dry form or through synthesis of UF. The denaturalisation of RB was carried out at different pHs (10-11) and at temperature 60°C for two hours. While incorporating the RB during synthesis of UF, it was carried out according to the method reported elsewhere. The formulation of adhesive components, pH value of the denaturalisation stage and the process of incorporating the RB were optimised. Assessment of the role of RB adhesive was specified from its free-formaldehyde (HCHO) content, as well as the properties (mechanical and physical properties) of the produced composites of bagasse particle board type, in comparison with the environmental impact of commercial thermosetting resin (UF). Findings – The promising adhesive system exhibits improvement in the environmental performance (as E1 type) over a commercially UF adhesive (as E2 type), besides providing boards fulfill the requirements of grade H-3 (according to ANSI A208.1 (NPA1993). This adhesive system was resulted from replacing 30 per cent of UF by denalturalised RB (at pH 10) in slurry form. Where, its reduction in free-HCHO reached 53 per cent, as well as modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB) and TS of the produced boards were approximately 24.2 N/mm2, approximately 3753 N/mm2, approximately 0.84 N/mm2 and approximately 11.4 per cent, respectively. Research limitations/implications – The eco-adhesive with relatively high percentage of low-cost commercial UF (70 per cent) and 30 per cent RB, as oil production by-product, in slurry form provides good board strength and is environmentally friendly compared to SCB-based composite properties, with that produced from commercial UF. The mechanical (MOR, MOE and IB) and water-resistance properties of the produced composite comply with the standard values. Practical implications – The approach provided low HCHO-free UF adhesive with good comparative board strength and water resistance and reasonable working life. Replacing 30 per cent of UF by RB in slurry form and denaturalised at pH 10 is considered a promising inexpensive alternate adhesive (as E1) in the wood industry based on SCB wastes. Social implications – Incorporating the RB by-product of oil production to commercial UF will be beneficial for saving the health of wood co-workers and motivating the wood mill to export its wood products. Originality/value – It provided a potentially simple way to improve both the utilisation of commercial UF and SCB as industrial substrates for particle-board production. This will benefit farmers, local wood mills in Upper Egypt, significantly. Meanwhile, incorporating low percentage of RB, as oil-mill by-products, is promising to partly replace UF resin in the wood industry, minimising formaldehyde emission or toxic gasses during board formation.

Use of tannin adhesive from Stryphnodendron adstringens (Mart.) Coville in the production of OSB panels

Stryphnodendron adstringens (Mart.) Coville is a species from the Cerrado (Brazilian tropical savanna) popularly known as barbatimao. Its main use of economic value lies in the extraction of the tannins found in its bark and leaves. The purpose of this study was to assess the technical viability of using a tannin-based adhesive coming from the bark of Stryphnodendron adstringens (Mart.) Coville for the production of Oriented Strand Board (OSB) panels. Tannin-based adhesives were produced from tannins extracted from the bark of barbatimao, and these adhesives were used in proportions of 0, 25, 50, 75 and 100 % with commercial urea–formaldehyde adhesive. The properties of the pure adhesives and the mixtures were determined. Subsequently, OSB panels were produced with urea–formaldehyde adhesives, tannin–formaldehyde adhesives and their mixtures. The panels were produced with wood from Pinus oocarpa, with 8 % adhesive, a press cycle of 40 kgf cm−2, and temperature of 160 °C for a period of 8 min. Only the OSB panels produced with 100 % urea–formaldehyde adhesive, 100 % barbatimao tannin adhesive and 25 % barbatimao adhesive combined with 75 % urea–formaldehyde fulfilled all the pre-requisites stipulated in the standard EN 300 (2006) for type 1 panels, thus proving to be technically viable for application in OSB panels.

Adesivos tânicos de Stryphnodendron adstringens (Mart.) Coville na produção de painéis aglomerados

O mundo busca fontes alternativas para a produção de adesivos utilizando matéria-prima renovável. Nesse contexto, a utilização de taninos da casca de barbatimão, Stryphnodendron adstringens (Mart.) Coville, tem apresentado potencial. O objetivo deste trabalho foi avaliar a viabilidade técnica de utilização de Adesivos tânicos provenientes das cascas de barbatimão para a produção de painéis aglomerados. Adesivos à base de taninos extraídos das cascas de barbatimão foram usados na proporção de 0, 25, 50, 75 e 100% com o adesivo comercial ureia-formaldeído. Os adesivos puros e o das misturas tiveram suas propriedades determinadas. Painéis aglomerados com os adesivos ureia-formaldeído, tanino-formaldeído e as misturas destes foram produzidos e suas propriedades físico-mecânicas, testadas. O adesivo tânico de barbatimão mostrou-se viável tecnicamente na proporção de até 50% para painéis reconstituídos do tipo aglomerado, com a ressalva de recomendação para uso apenas em ambientes internos, sem contato com a umidade.

Study of viscosity behavior and retanning properties of sulfonated glutaric dihydrazide formaldehyde condensate under different reactant ratios

Sulfonated glutaric dihydrazide formaldehyde condensates with less than 0.05% free formaldehyde were prepared through controlled reaction of glutaric dihydrazide, sodium metabisulfite, and formaldehyde in three processing steps. Mole ratio of sodium metabisulfite/glutaric dihydrazide (S/GDH) was varied from 0.1 to 0.5 and that of formaldehyde/glutaric dihydrazide (F/GDH) from 1 to 3. The effects on viscosity and fluidity of resins were observed with varying degrees of sulfonation and changeable mole ratio of formaldehyde/glutaric dihydrazide. Viscosity of resins showed increasing trend with increasing mole ratio of formaldehyde/glutaric dihydrazide and decreasing trend with increasing mole ratio of sodium metabisulfite/glutaric dihydrazide. Increase in viscosity of resins was due to increase in molecular weight of polymer chains. After gaining a critical molecular weight during condensation, resins turned into gel form. The resins were comparatively applied on chrome tanned cow hide against commercial sulfonated urea formaldehyde powder resin (Resin UFT).

ECO-Adhesive from Modified Natural Rubber for Wood Applications

Both commercial entities and the government have expressed interest in safe and environ-mentally friendly adhesives, ECO-adhesives, containing no volatile harmful or toxic chemicals. In the wood industries, currently common adhesives such as urea formaldehyde (UF), phenol formaldehyde (PF) release formaldehyde vapors that are a human health concern, with unpleasant odor. We examined the potential of modified natural rubber latexes (MNRL) for use as ECO-adhesives. Three latex types were used, namely epoxidized natural rubber (ENR), liquid natural rubber (LNR), and NR/PMMA blend. The MNRL was characterized by FT-IR, NMR, and GPC. The proportion of tackifying agent to the dry weight of latex was varied in the range 0 to 60 phr. It was found that the MNRL uniformly mixed in the latex form. All MNRL adhesives would have passed the Thai standard for rubber-based adhesives, based on their: total solids content (TSC), pH, viscosity, shear strength, and emissions of formaldehyde. Up to 30% fraction of tackifying agent, tack and shear strength increased with its content. Compared to a commercial UF adhesive, the MNRL had lower emissions of formaldehyde vapors, lower shear strength, but higher TSC, and higher viscosity. In summary, for select wood applications with moderate bond shear demands, these new rubber based adhesives could provide a health conscious and non-toxic alternative, with the further advantage of low odor.

Preparation and characterization of wood-plastic plywood bonded with high density polyethylene film

This paper presents a study on the potential use of high density polyethylene (HDPE) film as wood adhesive for formaldehyde-free plywood. The physical–mechanical properties of the plywood, including thickness swelling (TS), water absorption (WA), tensile shear strength, modulus of elasticity and modulus of rupture were evaluated. Results show that HDPE film dosage positively affects the properties when ranging from 61.6 to 246 g/m2. The performance of these panels was comparable to those of plywood made with commercial urea–formaldehyde (UF) resins. Comparisons of the dimensional stability between the two plywood demonstrated that 7-day TS and WA values of the panels bonded with UF resins were 5.10 and 23.5 % higher than those bonded with HDPE film, confirming the suitability of HDPE for the use as adhesive in wood-based composites intended for indoor applications subjected to high moisture. DMA tests show that HDPE bonded plywood was significantly inferior in thermal stability at 120 °C and above while it presented almost the same dynamic mechanical properties as UF plywood when the temperature was lower than 100 °C, making it suitable to be used as geothermal floor.

Novel fibers preparation technique for manufacturing of rice straw based fiberboards and their characterization

The present work introduces a novel fibers preparation technique for manufacturing of dry-formed rice straw based medium density fiberboard (RSMDF). The properties and the quality of the produced RSMDF were evaluated. The technique is based only on a mechanical method without pretreatment (wetting and chemical additives) before defiberation to loosen up the straw structure as usually followed in the conventional processes. The components of the manufacturing system were especially designed and fabricated. The commercial urea–formaldehyde UF resin was used as binder in manufacturing of the RSMDF. Different content levels of the conventional UF resin (16%, 18% and 19%) were targeted. The RSMDF was produced at different thicknesses (7mm, 9mm and 16mm) and average densities in the range of 728–941kg/m3. The RSMDF mechanical properties (internal bond (IB), modulus of rupture (MOR) and modulus of elasticity (MOE)) and thickness swilling (TS) were measured and analyzed as a function of density and resin content. The results revealed that, the properties of the produced fiberboards are dependent on the average density and the resin contents. The RSMDF panels were produced successfully using the new rice straw fibers preparation technique and their properties met the requirements of MDF standard.

Some Chemical Properties of Luffa and Its Suitability for Medium Density Fiberboard (MDF) Production

This study was conducted to evaluate suitability of luffa (Luffa cylindrica) fiber for medium density fiberboard (MDF) production. For the experiment, luffa and commercially manufactured fibers (Pinus sylvestris (30%), Fagus orientalis Lipsky (35%) and Quercus robur L. (35%)) with 11% moisture content were used. Luffa was mixed with commercially manufactured fibers in the following fashion: a layer of luffa fiber (30 g) placed in the middle of the mat, two equidistantly placed layers (60 g) in the mat, three layers (90 g) instead of two in the mat, and homogenously (90 g) dispersed without a district pattern in the mat, respectively. In panel production the only variable tested was the addition of luffa fiber at various weights to the wood fibers. Commercial urea formaldehyde (UF) adhesive was used as a binder. Chemical properties, including holo-, α-cellulose, and contents, alcohol-benzene solubility in dilute alkali (1% NaOH), and hot and cold water solubility, were determined. In addition, some physical and mechanical properties, such as density, thickness swelling (TS), bending strength (BS), modulus of elasticity (MOE), and internal bond (IB) of the panel of MDF were also measured. The chemical composition and solubility of luffa were found to be similar to those of nonwoods in general. Thus, the results suggest that luffa (Luffa cylindrica Mill.) fiber can be used as an alternative raw material for MDF manufacturing.

Mechanical characterization of industrial particleboard panels glued with cornstarch–mimosa tannin–urea formaldehyde resins

The aim of this work was to validate the utility and performance of optimal laboratory cornstarch–mimosa tannin-based resins in the industrial particleboard production. In this way, the cornstarch and mimosa tannin was introduced in the classic adhesive formulation in order to supply a part of urea-formaldehyde (UF). Our results show that industrial particleboard panels (8.2 m × 1.85 m × 19 mm) bonded with optimal cornstarch–mimosa tannin–UF (10:4:86; mass ratio) resins exhibited comparable mechanical properties to those of boards bonded with commercial UF resins and largely satisfied the exigencies of European norms EN 312. The formaldehyde emission levels obtained from panels bonded with cornstarch–mimosa tannin–UF were lower to those obtained from panels bonded with control UF. Finally, the addition of cornstarch and mimosa tannin improves markedly the water resistance of UF resins.

Potential utilization of burned wood in manufacture of medium density fiberboard

The potential utilization of burned wood in the manufacture of medium density fiberboard (MDF) was investigated. For this aim, the MDF panels were made of various mixtures of burned pine wood (Pinus sylvestris L.), unburned beech (Fagus orientalis L.) and oak (Ouercus robur L.) woods under commercial conditions in an MDF company. The mixture ratio of the unburned beech and oak woods to the burned pine wood were 50/50 wt%. The mixing ratios of burned wood chips with unburned wood chips were 0:100, 25:75, 50:50, 75:25 and 100:0, %, respectively. A commercial urea–formaldehyde resin was used as a binder. The physical properties measured in the investigation included density and thickness swelling, while the mechanical properties examined were bending strength, modulus elasticity, internal bond, screw holding ability perpendicular to the plane of panel, and janka hardness perpendicular to the plane of the panel. Surface roughness and color of the panels were also measured. The results indicated that all the panels met the mechanical properties of general-purpose MDF requirements of EN 622-5. The surface roughness of the MDF panels containing burned wood decreased with increasing burned wood content but remained higher than the control panels. The dimensional stability of the MDF panels decreased with the incorporation of burned wood fibers as compared with the control MDF panels.

Effects of Melamine on the Properties of Medium-Density Fiberboard Fabricated with Urea-Based Resins

Abstract Urea-melamine-formaldehyde (UMF) resins were synthesized and used for manufacturing medium-density fiberboard (MDF). As melamine content was increased at the same formaldehyde/urea (F/U) molar ratio, the solids content of the resin increased. Physical properties and storage stability of the resins tended to improve slightly when the final pH of resin was 8.5 compared with 7.5 and 9.5. At the same F/U molar ratio, free formaldehyde content and gel time of the resins decreased as melamine content increased. Chemical structures of the resins were proposed from the results of 13C nuclear magnetic resonance and Fourier transform infrared analyses. Formaldehyde emissions of MDF prepared with UMF resins with the same F/U molar ratio decreased as melamine content of resin was increased. MDF fabricated with UMF resin showed slightly better resistance against decay fungi and termites compared with MDF fabricated with urea-formaldehyde (UF) resin. Other physical properties of MDF fabricated with UMF resin were comparable to those of MDF fabricated with a commercial UF resin. An optimum F/U molar ratio of 1.2 with melamine content of 15 percent, equivalent to an F/(U+M) molar ratio of 0.98, was found from the results.

Wettability and surface roughness characteristics of medium density fiberboard panels from rhododendron (Rhododendron ponticum) biomass

Wettability and surface roughness properties of medium densityberboard (MDF) panels made from Rhododendron biomass were examined in this study. Rhododendron dominates the understory layer of the forests throughout the Black Sea Region in Turkey with substantial biomass potential. � is study was conducted to evaluate suitability of Rhododendronber for MDF production. For the experiments, rhododendron and commercially-manufactured-chip (Pinus sylvestris L. and Quercus robur L.) with 11% moisture content were used. � e mixing ratios of rhododendron with commercially-manufactured-chip were 100:0, 75:25, 50:50, 25:75 and 0:100 %, respectively. Commercial urea formaldehyde (UF) adhesive was used as a binder. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements by the stylus method were taken perpendicularly to theber. � ere was a signicant dierence (p=0.05) between surface roughness parameters (R a , R z , R q , and R y ). � e results obtained in this study revealed that all the panels have met the general purpose-use requirements of European Norm (EN). It was found that panels made with a 25/75 ratio of rhododendron to commercially-manufactured-chip had a signicantly lower contact angle (88.14 o ) than panels made with a 100/0 ratio (117.91 o ). Surface roughness measurements are based on four roughness parameters, average roughness (R a ), mean peak-to-valley height (R z ), root mean square roughness (R q ), and maximum peak-to-valley height (R y ) were considered to evaluate the surface characteristics of the panels and supported the above � ndings as the panels made with a 25/75 ratio had a slightly rougher surface with average values of 2.929 �m (R a ). From the tests performed, we conclude that increasing the rhododendron mixing portion increased surface roughness and decreased wettability. Based on these results, rhododendron biomass could be an alternative raw material for MDF manufacturing.

Performance characterizations of particleboards made with wheat straw and waste veneer splinters

The aim of this study was to determine the performance of three-layer particleboard made from wheat straw and veneer splinters, as waste materials. For the purpose of evaluation, compositions of wheat straw and beech veneer splinters at different mixture rates were compared for some of properties. Physical (thickness swelling and water absorption) and mechanical properties (modulus of rupture, modulus of elasticity, internal bond and impact strength) of the boards were evaluated. Effects of mixing ratios of fibrous material and press temperature on the above-mentioned properties were also investigated. The mixing ratios of beech veneer with wheat straw were 100%:0%, 75%:25%, 50%:50%, 25%:75% and 0%:100%, respectively. A commercial urea–formaldehyde (UF) adhesive was used as binder. A total of 10 experimental boards with an average target density of 0.70gcm−3 across all mixtures were fabricated. All the mechanical and physical properties of the boards were improved when the press temperature was increased from 140 to 170°C. Analysis of data revealed that the mechanical properties were significantly different among the board types. With the exception of modulus of elasticity, the other properties were decreased by the addition of wheat straw particles. In general, water absorption and thickness swelling decreased with the increase of wheat straw content. The presence of wheat straw in the particleboards resulted in higher water absorption and thickness swelling. Finally, it can be stated that wheat straw and beech veneer splinters have potential as supplement fibrous materials, in combination with wood particles for particleboard manufacturing and indoor applications.

Curing kinetics of two commercial urea-formaldehyde adhesives studied by isoconversional method

Differential scanning calorimetry (DSC) was used to evaluate the curing kinetics of two commercial urea-formaldehyde (UF) adhesives having different formaldehyde to urea (F/U) ratio of 1.112 (UF1) and 1.086 (UF2). DSC measurements were done in dynamic scanning regime with heating rates of 5, 10, 15 and 20?C?min-1 in order to determine the activation energy for each adhesive. Obtained data were analyzed using isoconversional methods with application of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose kinetic models. In addition, different catalyst levels were tested at the heating rate of 10?C/min. Results showed that the adhesive with higher F/U ratio achieved higher activation energy, while having lower peak temperature of curing reaction. It was also noticed that the increase of catalyst level influenced the increase of reaction enthalpy of the adhesive with lower F/U ratio.

Resistance of phenolic-treated oil palm stem plywood against subterranean termites and white rot decay

The objectives of the study were to evaluate the effectiveness of phenolic resin in protecting oil palm stem (OPS) plywood against both subterranean termites (Coptotermes curvignathus) and white rot fungi (Pycnoporous sanguineus). Specially cooked, Low molecular weight phenol formaldehyde (LMW PF) resin was used to treat the OPS veneer whilst commercial urea formaldehyde (UF) resin was used to bond the phenolic-treated veneer. OPS plywood were produced using two types of lay-up (100% outer veneer type and 100% inner veneer type) with adhesive spread rate of 200g/m2. The results show that treatment of OPS veneer with LMW PF has significantly enhanced the resistance of OPS plywood against both termites and white rot fungi. In the termites resistance test, the percentage of weight loss for untreated samples were 19.2% (outer veneer) and 23.9% (inner veneer), while for phenolic treated samples were only 10.7% and 15.8%, respectively. The phenolic treatment was able to enhance the resistance towards termites by 38% and towards white rot fungi by 62%. The study has shown LMW PF resin can be used to protect OPS plywood from termites and white rot fungi.

Sound insulation property of wood–waste tire rubber composite

The sound insulation property of wood/used tire rubber composite panel (WRCP) was investigated. A four-microphone method was used to measure the sound transmission losses of three different composite panels: WRCP, commercial compound wooden floorboard and commercial wood-based particleboard. The WRCP was manufactured in the lab with commercial urea–formaldehyde (UF) and polymeric methylene diphenyl diisocyanate (PMDI) adhesives. The test results indicated that sound insulation property of WRCP is better than that of commercial compound wooden floorboard and wood-based particleboard. In addition, the acoustic insulation of WRCP is significantly affected by the amount of rubber crumbs and PMDI adhesive used in the composite. An increase in the usage of recycled tire rubber crumbs and the dosage of PMDI adhesive significantly improve the soundproof property of the WRCP. Moreover, the microstructure of WRCP was examined using a scanning electron microscope (SEM). The sound insulation effect is also dependant on the microstructure of the interface zone of wood/rubber and densification of WRCP. The continuous interfaces are formed in the presence of sufficient UF and PMDI adhesives resulted in better soundproof WRCP.

Cornstarch–mimosa tannin–urea formaldehyde resins as adhesives in the particleboard production

AbstractThe objective of this work was to demonstrate the utilisation of cornstarch–mimosa tannin‐based resins designed for application as an adhesive in particleboard production. Bond qualities of cornstarch–mimosa tannin–urea formaldehyde (UF) resins and commercial UF resin were assessed by using an automatic bonding evaluation system, prior to production of particleboards panels. In order to evaluate the quality of cornstarch–mimosa tannin–UF resins, particleboards were produced and physical and mechanical properties were investigated. These physical properties included rheological, thermogravimetric analysis and solid phase 13C NMR analysis of resins. Internal bond, surface soundness, thickness swelling, porosity, modulus of rupture and modulus of elasticity mechanical properties of particleboards bonded with cornstarch–mimosa tannin–UF resins were also determined.The results showed that it is possible to add cornstarch and mimosa tannin, respectively, up to 10 and 4% to the UF resin without to alter the physical and mechanical properties of the boards. The performance of these panels is comparable to those of boards made using commercial UF resin. Petrochemical UF resins could be partially substituted in industrial applications by addition of cornstarch and mimosa tannin extracts.