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Various methods for the effective modification of urea–formaldehyde (UF) adhesives, aimed at enhancing the performance of wood-based materials, have been continually explored worldwide. The aim of this work was to investigate and evaluate the effect of introducing small amounts (0.25–1.5%) of activated carbon from coconut shells (ACCS) in UF adhesive on the properties of particleboard. The performed investigations of the adhesive mixture's properties showed an increase in both viscosity and reactivity. Moreover, the use of loadings of 0.75% and 1% had a positive effect on mechanical properties such as bending strength, modulus of elasticity, and internal bond. In these variants, a delay in the degradation of the adhesive bonds by water was also observed, as indicated by the lower thickness swelling values measured after 2 h. However, under long-term exposure to water, the modification had no considerable effect on the dimensional stability of the boards. Markedly, the addition of 1 and 1.5% of ACCS resulted in a reduction in formaldehyde content, which can be attributed to the excellent adsorption capacity of activated carbon. Overall, a loading of 1% was found to be optimal, resulting in improved strength, enhanced water resistance, and reduced formaldehyde content. [ABSTRACT FROM AUTHOR]

Particleboards have gained attention in the global market. Understanding their physical–mechanical behavior in the current technological context is essential due to adhesive polymerization, which depends on variables such as pressing time and temperature. Today, the use of nanoparticles has become a plausible option for improving the properties of polymers used in wood-based composites. This study evaluates the influences of the addition of non-commercial 0.5% aluminum oxide (Al2O3) and aluminum oxide copper (CuO) nanoparticles using a greener route with a lower environmental impact obtaining a urea-formaldehyde (UF)-based polymeric adhesive to manufacture particle composites of Eucalyptus urophylla var. grandis wood. Regarding characterizations, the resin properties analyzed were viscosity, gel time, and pH, as well as panel properties, including density, moisture content, thickness swelling, modulus of elasticity, modulus of rupture, and thermal conductivity. The results were compared with scientific publications and standards. The addition of nanoparticles interfered with viscosity, and all treatments indicated a basic pH. It was not possible to determine the gel time after 10 min. Nanoparticles added to the polymers in the internal layer did not cause an improvement in the swelling properties in terms of thickness, with no significant statistical difference for density and moisture content. The increase from 150 °C to 180 °C may have caused an improvement in all physical–mechanical properties, indicating that the higher temperature positively influenced the polymerization of the formaldehyde-based adhesive. Therefore, the additions of both nanoparticles (0.5% in each condition) led to a limitation in the material influence with respect to physical–mechanical performance. [ABSTRACT FROM AUTHOR]

Currently, the industrial success of bio-based adhesives remains limited, despite the growing interest in these compounds. One example is the use of lignosulfonates (LS), a byproduct from the pulp and paper industry, which requires long pressing times to ensure proper performance for wood-based panel production. This study successfully manufactured particleboards using a low press factor of 7.5 s/mm, commonly used for conventional urea-formaldehyde resins on a lab scale. To the best of our knowledge, lignin-based particleboards have never been reported using such low press factors. Thus, 3-layer boards were manufactured in which the core layer was bonded with polymeric isocyanate (pMDI), and the surface layers were bonded with LS. Propylene carbonate (PC) was used as a solvent for pMDI to improve adhesive distribution. The optimum amounts of adhesive were determined using response surface methodology: 1.3% pMDI with 2.2% PC in the core layer and 15% LS in the surface layers. These boards obeyed the requirements of standard EN 312 for general-purpose boards for use in dry conditions (type P1). Their formaldehyde content, determined through the perforator method, was equal to that of the wood mix at the maximum value set by IKEA for class E0.5. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the physical and mechanical properties of particleboards fabricated from Vernonia arborea Buch.-Ham and Eleocharis sp. fibers with PVAc adhesive based on the SNI 03-2105-2006. A two-factor factorial in completely randomized design was used with adhesive contents of 10% and 20% as the first, and ratios of V. arborea Buch.-Ham to Eleocharis sp. of 30/70, 50/50 and 70/30 as the second factor. The materials were V. arborea Buch.-Ham wood shaving (mesh size of 4), Eleocharis sp. (chop length of 1-2cm), and PVAc adhesive. The parameters were moisture content, density, water absorption, and thickness swelling for physical properties, and modulus of elasticity, modulus of rupture, internal bond strength, and screw holding strength for mechanical properties. However, both properties do not meet the SNI 03-2105-2006 (except for thickness swelling), allegedly caused by imprecise concentration and uneven distribution of PVAc. Additionally, 3h boiling of Eleocharis sp. is not able to remove its wax layer, causing less optimal adhesion between materials. Particleboard with 20% PVAc shows the best result. Principally, the adhesive concentration has significant effects, while the combination between V. arborea Buch.- Ham and Eleocharis sp. has insignificant effects on the physical and mechanical properties of particleboards. The evaluated composition is recommended for interior uses (partition walls, wall panels, information boards, and lightweight ceilings), with the addition of coating to improve durability and decorative value. As an additional material, Eleocharis sp. has a high sustainability value due to its availability in nature. [ABSTRACT FROM AUTHOR]

The application of commonly used flame retardants in most cases causes reduction in strength characteristic of particleboard. Therefore, it was decided to carry out research aimed at determining possibility of using pMDI-reinforced PF adhesive to produce board with increased fire resistance. The effect of different shares of particles impregnated with a mixture of potassium carbonate and urea on the particleboard properties such as density, density profile, bending strength, modulus of elasticity, internal bond and internal bond after boiling was investigated. Presented work also determined the effect of fire retardant on the performance of particleboards after ageing test and their reaction to fire. Studies demonstrated that PF adhesive modified with 20% pMDI is suitable for gluing impregnated wood particles. Regardless of their share, resultant panels showed no changes in strength and density. In the case of boards consisting of impregnated particles in the amount of 75% and 100%, lower values of swelling were demonstrated. The boards were classified as load-bearing boards for use in humid conditions. Fire retarding efficiency was confirmed by lowered mass loss, prolonged time needed to reach maximal burning rate, decreased gross calorific value and reduced ignitability when exposed to both radiant heat source and small flame source. [ABSTRACT FROM AUTHOR]

Reducing harmful emissions from wooden materials is a major challenge for the wood industry. This is particularly important for the particleboard sector, where the use of formaldehyde-based resins can cause substantial pollutant emissions. With the aim of finding a greener alternative to commercial resins, the authors applied four types of liquefied lignocellulosic biomass and two types of nanocellulose-based formulations as a partial replacement of melamine-urea-formaldehyde resin for single-layer particleboard manufacturing and tested: formaldehyde content, formaldehyde and volatile organic compounds (VOC) emissions of the boards. The results revealed reduced formaldehyde content (up to −20%) and a slight decrease (max −13%) in formaldehyde emission in comparison to the panel produced with commercial resin when applying liquefied biomass in the adhesive mass. The values of VOC emissions in the particleboards developed with the alternative adhesive systems were substantially lower in comparison to the commercial panel, especially for γ-methacryloxypropyl-trimethoxysilane nanocellulose, which allowed to achieve a reduction of about 67% of total VOC emissions. Overall, liquefied wood products obtained from softwood bark showed the best performance in decreasing the emissions. The results confirmed the research hypothesis that the use of liquefied lignocellulosic biomass and nanocellulose can reduce the emissions of harmful substances from the wood-based panels. [ABSTRACT FROM AUTHOR]

Purpose: In industrial applications, formaldehyde-based wood adhesives have been used extensively because of their low costs and high reactivity. However, their real-world applications are hindered by some main bottlenecks, especially the formaldehyde emission and usage of nonrenewable raw materials. The purpose of this study is the development of sustainable and formaldehyde-free wood adhesive formulation. Design/methodology/approach: In this study, starch and tannin-based wood adhesive were synthesized. Chemical structures and thermal properties of the prepared bio-based resin formulations were elucidated by using Fourier transform infrared and differential scanning calorimetry analysis, respectively. Laboratory scale particleboard production was carried out to determine the performance of the developed resin formulations. Obtained results were evaluated in dry medium (P2) according to European norms EN 312 (2010). Furthermore, the board formaldehyde content was determined by using the perforator method according to the European Norm EN 12460-5. Findings: The results show that the improved starch and tannin-based wood adhesives were successful in their adhesive capacity, and the formaldehyde content of the final product was obtained as low as 0.75 mg/100 g. This paper highlights that the presented adhesive formulations could be a potential eco-friendly and cost-effective alternative to the formaldehyde-based wood adhesives for interior particleboard production. Research limitations/implications: Starch-based resins in the liquid form needed to be continuously mixed throughout their shelf life to prevent the starch from settling because it was not possible to dissolve the precipitated starch again after a while. For this reason, starch was given to the chips in powder form while preparing the particleboard. Practical implications: In conclusion, this study shows that the developed bio-based resin formulations have a high potential to be used for producing interior-grade particleboards instead of commercial formaldehyde-based wood adhesives because the obtained results generally satisfied the interior grade particleboard requirements according to European norms EN 312, P2 class (2010). In addition, it was determined that the produced boards had significantly low formaldehyde content. The low formaldehyde content of the final boards was not because of the resin but because of the natural structure of the wood raw material, press parameters and environmental factors. Social implications: The developed bio-based resin system made it possible to obtain boards with significantly low formaldehyde content compared to commercial resins. Originality/value: The developed bio-based resin formulation made it possible to produce laboratory-scale board prototypes at lower press factors and board densities compared to their counterparts. [ABSTRACT FROM AUTHOR]

This paper investigated the upcycling process of thermoplastic waste polystyrene (WPS) into thermosetting particleboard adhesive using two cross-linkers, namely methylene diphenyl diisocyanate (MDI) and maleic anhydride (MA). The WPS was dissolved in an organic co-solvent. The weight ratio of WPS/co-solvent was 1:9, and 10% of cross-linkers based on the WPS solids content were added subsequently at 60 °C under continuous stirring for 30 min. The adhesive properties, cohesion strength, and thermo-mechanical properties of WPS-based adhesives were examined to investigate the change of thermoplastic WPS to thermosetting adhesives. The bonding strength of WPS-based adhesives was evaluated in particleboard made of sengon (Falcataria moluccana (Miq.) Barneby & J.W. Grimes) wood and rice straw particles at different weight ratios according to the Japanese Industrial Standard (JIS) A 5908:2003. Rheology and Dynamic Mechanical Analysis revealed that modification with MDI and MA resulted in thermosetting properties in WPS-based adhesives by increasing the viscosity at a temperature above 72.7 °C and reaching the maximum storage modulus above 90.8 °C. WPS modified with MDI had a lower activation energy (Ea) value (83.4 kJ/mole) compared to the WPS modified with MA (150.8 kJ/mole), indicating the cross-linking with MDI was much faster compared with MA. Particleboard fabricated from 100% sengon wood particles bonded with WPS modified with MDI fulfilled the minimum requirement of JIS A 5908:2003 for interior applications. [ABSTRACT FROM AUTHOR]

Adhesives are significant for manufacturing competent, light, and sturdy goods in various industries. Adhesives are an important part of the modern manufacturing landscape because of their versatility, cost-effectiveness, and ability to enhance product performance. Formaldehyde and polymeric diphenylmethane diisocyanate (PMDI) are conventional adhesives utilized in wood applications and have been classified as carcinogenic, toxic, and unsustainable. Given the adverse environmental and health effects associated with synthetic adhesives, there is a growing research interest aimed at developing environmentally friendly bio-based wood adhesives derived from renewable resources. This study aimed to extract starch from camote and cassava peels and focuses on the oxidization of starch derived from camote and cassava peels using sodium hypochlorite to create bio-based adhesives. The mean yield of starch extracted from camote and cassava peels was 13.19 ± 0.48% and 18.92 ± 0.15%, respectively, while the mean weight of the oxidized starches was 34.80 g and 45.34 g for camote and cassava, respectively. Various starch ratios sourced from camote and cassava peels were examined in the production of bio-based adhesives. The results indicate that the 40:60 camote to cassava ratio yielded the highest solid content, while the 80:20 ratio resulted in the best viscosity. Furthermore, the 40:60 ratio produced the most favorable particle board in terms of mechanical properties, density, thickness, swelling, and water absorption. Consequently, the starch extracted from camote and cassava peels holds promise as a potential source for bio-based adhesives following appropriate chemical modification. [ABSTRACT FROM AUTHOR]

Wood chipboard, common in interior spaces for applications ranging from furniture to decorative panelling, often falls short due to the presence of toxic adhesives, posing risks to both human health and the environment. This research delves into the potential transformation of wood chipboard into a 100% bio-based product. Previous research has shown the possibility of the partial replacement of petrochemical-based adhesives with bio-based adhesives. Hence, previous results do not reach the policy ambitions of the Green Deal of making the Green Transition to a bio-based economy. For chipboard production, logging residues from Latvian State Forests were systematically gathered within two months post-logging, comprising primarily Picea abies and Pinus sylvestris biomass, including branches, needles, bark, and various particles. A custom chipper and Vibrotehnik PM-120 hammer mill were employed for particle size separation into three fractions via sieving: <2.8 mm, 2.8–8 mm, and 8.0–10.0 mm, and combined with binders and hot-pressed into board samples. As a result, particle boards containing 100% bio-based carbon were achieved, demonstrating the possibility of excluding petroleum adhesives from chipboard production, paving the way for new research exploring bio-based binders and conifer bark. [ABSTRACT FROM AUTHOR]

The development of a biodegradable adhesive that uses waste from industry will bring enormous economic, social, environmental, and health benefits. Many laboratories around the world conduct research on the development of natural adhesives that can replace those based on toxic formaldehyde. Works in this area are also carried out by Sestec Polska Sp. z o. o, an example of which is the Sestec B0021G adhesive. This product belongs to the family of animal protein-based adhesives and is dedicated to particle board (PB) production (classes P1–P5 according to EN 312). This work presents the results obtained during the preparation of boards based on Sestec B0021G protein adhesive, manufactured with the use of variable production parameters, and assesses the influence of these parameters on the properties of the obtained products. The emphasis was especially on presenting the impact of production parameters on the PB strength and water resistance. The tests were carried out using different densities (560–800 kg/m3), pressing temperatures (150–230 °C), amounts of adhesive (7–15% in the surface layer and 5–13% in the core layer) and specific press times (5–13 s/mm). The boards showed excellent mechanical properties and water resistance. Higher PB classes were obtained under standard production conditions. Eventually, the obtained results showed that the binder can be used to produce all classes of PB products P1 to P7, and not only P1-P5 as initially assumed. [ABSTRACT FROM AUTHOR]

Particleboards with different combinations of the adhesive material imidazole, citric acid, and sorbitol were produced. Softwood sawdust from a Swedish sawmill was mixed with an aqueous solution of the chemicals and then dried to 0% moisture content prior to pressing. The boards were pressed to a target density of 700 kg m−3 at either 200 °C or 220 °C for 10 min. The hygroscopic and mechanical properties of the boards were clearly better at 220 °C than 200 °C for all used chemical combinations. A combination of imidazole (14.4 wt%) and citric acid (11.3 wt%) led to the best results, where the thickness swelling after 24 h of water immersion was 6.3% and the internal bonding strength was 0.57 MPa. The modulus of rupture and modulus of elasticity were 3.3 MPa and 1.1 GPa, respectively. Cyclic accelerated weathering showed exceptional stability with a thickness change after boiling and drying of only 2.1% compared to the initial dry thickness. This study indicates that the presence of imidazole leads to greatly improved hygroscopic properties and good internal bonding strength when used in particleboards. [ABSTRACT FROM AUTHOR]

The use of alternative raw materials, such as agricultural biomass and by-products, in particleboard (PB) production is a viable approach to address the growing global demand for sustainable wood-based materials. The purpose of this study was to investigate the effect of the type of hardener and tannin-glyoxal (TG) adhesive formulation on the cohesion and adhesion performance of TG adhesives for areca-based PB. Two types of hardeners were used, NH4Cl and NaOH, and three adhesive formulations with tannin:glyoxal ratios (i.e., F1 (1:2), F2 (1:1), and F3 (2:1)) were applied to improve the cohesion performance and adhesion for areca-based TG adhesive for PB. The basic, chemical, and mechanical properties of the TG adhesive were investigated using a Fourier transform infrared spectrometer, rotational rheometer, dynamic mechanical analyzer (DMA), and X-ray diffractometer. The results show that a high glyoxal percentage increases the percentage of crystallinity in the adhesive. This shows that the increase in glyoxal is able to form better polymer bonds. DMA analysis shows that the adhesive is elastic and the use of NH4Cl hardener has better mechanical properties in thermodynamic changes than the adhesive using NaOH hardener. Finally, the adhesion performance of the TG adhesives on various types of hardeners and adhesive formulations was evaluated on areca-based PB panels. Regardless of the type of hardener, the TG adhesive made with F1 had better cohesion and adhesion properties compared to F2 and F3. Combining F1 with NH4Cl produced areca-based PB panels with better physical and mechanical qualities than the adhesive formulations F2 and F3, and complied with Type 8 particleboard according to SNI 03-2105-2006 standard. [ABSTRACT FROM AUTHOR]

The utilization of sustainable lignin to synthesize wood adhesives has attracted increasing attention in recent years. However, the facile fabrication of strong and environmentally friendly lignin-based adhesives with a high lignin content remains a significant challenge. In this study, we developed a formaldehyde-free wood adhesive system by combining alkali lignin and poly(propylene glycol) bis(2-aminopropyl ether). The process of producing lignin-based adhesives involves a simple mixing of wood flour, lignin, and a commercially available crosslinker (polyetherimide), followed by direct hot-pressing into particleboards. The lignin-based adhesive showed a high biomass content of 75 wt% (crosslinker accounting for 25 wt%) and the internal bonding strength of the formaldehyde-free and non-toxic particleboards was 1.42 MPa, outperforming many other bio-based adhesives. The study demonstrates a new and facile strategy to synthesize a lignin-based thermoset that is readily and practically applicable as an adhesive to fabricate high-performance, high lignin content, and formaldehyde-free wood products. [ABSTRACT FROM AUTHOR]

The environmental crisis and the safeguarding of the population's health has led to research into different ways of mitigating harmful gases. Among the emissions that the wood industry has sought to reduce are those of formaldehyde, which is why new green adhesive methods for wood panels have been investigated in recent years. In this research, particleboard with two bio-based wood adhesive (PB-bbwa) formulations. The first PB-bbwa formulation, based on proteins obtained from compounds from the alcoholic beverage industry, and the second PB-bbwa formulation, based on proteins from a mixture of compounds from the alcoholic beverage and food industries, were manufactured and tested to evaluate the physical–mechanical, thermal and formaldehyde emission properties of untreated and UV-treated formulations at a laboratory scale. The results of the physical properties obtained in the PB-bbwa were similar or even better than those of the control PB. Additionally, PB-bbwas improve on the control PB sample's Janka hardness by least 28%, and a decrease in thermal conductivity in the edgewise position and formaldehyde emissions by 12% and 88%, respectively, in comparison to the control PB. The tests performed evidenced that PB-bbwas showed comparable performance against the control PB made with urea-formaldehyde and satisfied international standard requirements. [ABSTRACT FROM AUTHOR]

Most adhesives used in the wood-based panel (WBP) industry are petroleum-based and are associated with environmental impact and price fluctuations. Furthermore, most have potential adverse health impacts, such as formaldehyde emissions. This has led to interest from the WBP industry in developing adhesives with bio-based and/or non-hazardous components. This research focuses on the replacement of phenol-formaldehyde resins by Kraft lignin for phenol substitution and 5-hydroxymethylfurfural (5-HMF) for formaldehyde substitution. Resin development and optimization was carried out regarding varying parameters such as molar ratio, temperature or pH. The adhesive properties were analyzed using a rheometer, gel timer and a differential scanning calorimeter (DSC). The bonding performances were evaluated using an Automated Bonding Evaluation System (ABES). Particleboards were produced using a hot press, and their internal bond strength (IB) was evaluated according to SN EN 319. Hardening of the adhesive could be achieved at low temperatures by increasing or decreasing the pH. The most promising results were obtained at pH 13.7. The adhesive performances were improved by adding filler and extender (up to 28.6% based on dry resin) and several boards were produced reaching P1 requirements. A particleboard achieved a mean IB of 0.29 N/mm2, almost reaching almost P2 requirements. However, adhesive reactivity and strength must be improved for industrial use. [ABSTRACT FROM AUTHOR]

The performance of urea-formaldehyde (UF) resin and its formaldehyde emission is a natural contradiction. High molar ratio UF resin performance is very good, but its formaldehyde release is high; low molar ratio UF resin formaldehyde release is reduced, but the resin itself performance becomes very bad. In order to solve this traditional problem, an excellent strategy of UF resin modified by hyperbranched polyurea is proposed. In this work, hyperbranched polyurea (UPA6N) is first synthesized by a simple method without any solvent. UPA6N is then added into industrial UF resin in different proportions as additives to manufacture particleboard and test its related properties. UF resin with a low molar ratio has a crystalline lamellar structure, and UF-UPA6N resin has an amorphous structure and rough surface. The results show that internal bonding strength increased by 58.5%, modulus of rupture increased by 24.4%, 24 h thickness swelling rate (%) decreased by 54.4%, and formaldehyde emission decreased by 34.6% compared with the unmodified UF particleboard. This may be ascribed to the polycondensation between UF and UPA6N, while UF-UPA6N resin forms more dense three-dimensional network structures. Finally, the application of UF-UPA6N resin adhesives to bond particleboard significantly improves the adhesive strength and water resistance and reduces formaldehyde emission, suggesting that the adhesive can be used as a green and eco-friendly adhesive resource for the wood industry. [ABSTRACT FROM AUTHOR]

In recent years, the most important challenge for wood-based panel's producers has been an increasing demand for wood raw materials, raw material prices, and rising transportation costs. On the other hand, the application of lightweight elements in the manufacture of decorative furniture has received more attention. The present study aimed at evaluating the effect of different levels of size and the amount of expanded polyurethane particles in the production of lightweight particle boards. The size of polyurethane particles at three levels (10, 5, and 15 mm) and the amount at four levels (10, 5, 0, and 15%) were selected as variable factors, and the amount of adhesive consumption, press pressure, board thickness, and final density were considered as fixed factors. The results showed that flexural strength, the flexural modulus of elasticity, internal bonding, and thickness swelling increased significantly with increasing the size of polyurethane particles in the middle layer of the board, but the effect of size was not significant on the water absorption of the samples. Also, increasing the percentage of polyurethane in the middle layer increased the mechanical properties and improved the physical properties compared to the control sample, and it had the largest effect on the internal bonding of the samples. [ABSTRACT FROM AUTHOR]

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Restricted formaldehyde gas emissions and a scarcity of lignocellulosic raw materials have particleboard companies in Iran concerned about raw materials and adhesive use. The particle slenderness ratio is one of the main parameters that leads to the required mechanical characteristics of particleboard, together with the simultaneous decrease of density (raw materials) and the quantity of adhesive. The objective of this study was to evaluate the mechanical properties of particleboard composed of poplar particles with variables of density, adhesive quantity, and slenderness ratio using response surface technique. The variables were then optimized for the examined responses according to the EN 312-3 (1993) standard for the manufacturing of particleboard for domestic use as well as home and office furniture. Particleboard with minimum allowable properties according to EN 312-3 (MOR = 11 MPa, MOE = 1.6 GPa, and IB = 0.35 MPa) with a density of 0.65 g/cm3, adhesive percentage of 10.54, and a slenderness ratio of 37.5 can be produced, according to optimization findings. Through raising the density to 0.69 g/cm3 and the slenderness ratio to 46.99, the quantity of adhesive utilized in particleboard manufacturing could be decreased from 10.54 to 8.9% while keeping the minimum allowable resistances of EN 312-3 (1993) standard. [ABSTRACT FROM AUTHOR]

Free formaldehyde is a carcinogen whose emission reduction in particleboard has been studied recently to mitigate this environmental and human health problem. One alternative to reduce the emission of formaldehyde in particleboards is by using adhesives produced from natural sources. Cardanol-formaldehyde is an environmentally friendly adhesive made with cashew nut liquid, a byproduct from the cashew chain. This work aimed to produce particleboard using cardanol-formaldehyde in place of urea. In addition, different proportions of bean straw wastes were used to replace pine wood. The combination of eco-friendly adhesive and lignocellulosic waste particles could result in a product that meets market demands while being environmentally nonaggressive. Cardanol-formaldehyde promoted a higher modulus of elasticity (MOE) (1172 MPa) and modulus of rupture (MOR) (4.39 MPa) about panels glued with urea–formaldehyde, which presented a MOE of 764 MPa and MOR of 2.45 MPa. Furthermore, the cardanol-formaldehyde adhesive promoted a 93% reduction in formaldehyde emission, with a reduction from 16.76 to 1.09 mg/100 g oven-dry board for particleboards produced with cardanol-formaldehyde, indicating potential as an adhesive in the particleboard industry. [ABSTRACT FROM AUTHOR]

The proportion of bark in tree trunks is in the range of ~ 10–20%. This large amount of material is currently mainly considered as a by- or even waste-product by the timber processing industry. Recently, efforts towards the use of bark have been made, e.g. as a raw material to harvest different chemical compounds or as an additive for wood particle boards. Our motivation for this work was to keep the bark in an almost natural state and explore alternative processes and applications for use. The traditional method of de-barking tree trunks by peeling was used to harvest large bark pieces. Two pieces of peeled bark were placed crosswise, with the rhytidom side (outer bark) facing each other. After different conditioning steps, bark pieces were hot pressed to panels without adding adhesives. These experiments on bark samples of different Central European tree species suggest that production of panels with species dependent properties is possible and feasible. This is a step towards producing sustainable panels by using a natural waste material, while retaining its beneficial structure and its natural chemical composition. [ABSTRACT FROM AUTHOR]

In the production of particleboard, the chips emerging from the drying oven usually pass into the bonding process without sufficiently cooling down. Moreover, along with the effect of friction during the bonding process, the increased chip temperature boosts the consumption of resin/adhesive and affects the properties of the board. This study investigated the effect of chip temperature during the bonding process on the properties of particleboard. With this aim, the effects were determined for six different temperatures (25 °C, 30 °C, 35 °C, 40 °C, 50 °C, 55 °C) measured during the bonding of the chips. According to the results, optimum board properties were obtained from the groups in which the chip temperature measured during the bonding process was 30 °C - 40 °C. Furthermore, it was determined that chip temperatures of above 40 °C during the bonding process significantly reduced the mechanical properties. [ABSTRACT FROM AUTHOR]

This physical and mechanical properties of a table tennis blade made from sorghum bagasse particleboard (TTBSB-particleboard) bonded maleic acid adhesive was investigated under pressing temperature and time variations. The TTBSB-particleboard was produced via a two-stage process in this study. A pressing temperature of 170–200 °C was used to prepare the first stage for 10 min. Following this, the second stage of the TTBSB-particleboard was produced with a different pressing time of 5–20 min. The TTBSB-particleboard had a specified target density of 0.6 g/cm3 and a size of 30 cm × 30 cm × 0.6 cm, respectively. For references concerning the tested quality of TTBSB-particleboard, the JIS A 5908-2003 standard has been used. For comparison, the commercial blades of Yuguan Wooden 1011 and Donic Original Carbo Speed were tested under the same conditions. The quality of the TTBSB-particleboard was successfully enhanced by increasing the pressing temperature (170 to 200 °C) and time (5 to 20 min). As a result, the pressing condition of 200 °C and 20 min were effective in this study. The TTBSB-particleboard in this study has a greater weight than the commercial blades of Yuguan and Donic. However, the TTBSB-particleboard in this study had a ball rebound comparable to that of the Donic blade. [ABSTRACT FROM AUTHOR]

The European standard EN 438-2 (2019) describes a method to assess the resistance to cracking of high-pressure laminate (HPL). In the EN 438-2 setup, the samples' shrinkage at a temperature of 50 °C for 6 h is restrained by a metal clamp. The resulting tensile stress may lead to the cracking of the laminate. With the intention to gain additional insight into the parameters and influencing factors of the standard test, the resistance to cracking of 43 laminates was tested in accordance with the standard and with a prolonged testing time. Additionally, the tensile strength and shrinkage of the laminates were determined under the conditions of the standard test. The standard test uses free laminates (laminates not glued to a carrier board), so in order to correlate the results to applications that are close to real-life situations, four of the laminates were also tested when glued to carrier boards the size of furniture doors. In this full factorial test, particle board and gypsum board were used as carrier boards, UF and PVAc as adhesives, and the possible shrinkage of the laminates was adjusted by two moisture conditions of the laminates. The resistance to cracking in the standard test turned out to be mainly influenced by the composition of the laminate. Thin laminates with a pure paper backing were especially prone to cracking in the setup. Within the 6 h storage at 50 °C of the standard test, the laminates did not reach moisture equilibrium. Prolonged storage at 50 °C until equilibrium was reached (which took up to 10 days) allowed an improved differentiation of the cracking resistance, especially of thicker laminates. Four of the laminates were also tested on wooden and mineral-based carrier boards with either PVAc or UF as adhesive and two moisture contents of the laminates. The following parameters were identified as a critical combination for cracking: laminate with a low cracking resistance according to the EN 438-2 test in combination with a non-hygroscopic mineral-based carrier board, increased moisture of the laminate before being glued on the board, and the use of PVAc adhesive. [ABSTRACT FROM AUTHOR]

The study evaluates the performance of laboratory, single-layered particleboards made out of fructose-hydroxymethylfurfural-bishexamethylenetriamine (SusB) adhesive as a sustainable alternative. Several production parameters such as mat moisture content (MMC), adhesive amount and press time were varied and their effect on the bonding efficiency investigated. The internal bond strength (IB) and thickness swelling after 24 h of water immersion (TS) were taken as evaluation criteria for the bonding efficiency. pMDI-bonded particleboards were produced as fossil-based, formaldehyde-free reference. Particleboard testing was complemented by tensile shear strength measurements and thermal analysis. It was found that the MMC has the highest impact on the internal bond strength of SusB-bonded particleboards. In the presence of water, the reaction enthalpy of the main curing reaction (occurring at 117.7 °C) drops from 371.9 J/mol to 270.5 J/mol, leading to side reactions. By reducing the MMC from 8.7%, the IB increases to 0.61 N/mm2, thus surpassing P2 requirements of the European standard EN312. At a press factor of 10 s/mm, SusB-bonded particleboards have a similar IB strength as pMDI-bonded ones, with 0.59 ± 0.12 N/mm2 compared to 0.59 ± 0.09 N/mm2. Further research on the improvement of the dimensional stabilization of SusB-bonded PBs is needed, as the TS ranges from 30–40%. [ABSTRACT FROM AUTHOR]

The following research aims to evaluate the feasibility of manufacturing particleboards based in Pinus radiata D. DON (PC) and Eucalyptus globulus (EC) capsules bonded with a natural oil polyurethane adhesive (PU). The particles of PC and EC were ground and dried. Particleboards were manufactured with PC and EC bonded with a natural oil‐based polyurethane adhesive (PC–PU and EC–PU). Boards composed of radiata pine wood and bio based polyurethane adhesive (RP–PU) and with radiata pine wood bonded with urea formaldehyde resin (RP–UF) were manufactured as reference samples. The physical and mechanical properties and formaldehyde emissions were evaluated according to international standards. The superficial morphology of the particleboards was studied through optical microscopy (OP) and scanning electron microscopy (SEM). The novel particleboards showed high resistance to moisture, low thickness swelling and a high internal bond strength, when compared with particleboards manufactured with the radiata pine wood particleboards bonded with PU and UF. Flexural properties in the new particleboards were slightly lower than the flexural properties of the reference samples RP–PU and RP–UF, since the distribution and geometry of the particles were different. The results of this research validate the use of P. radiata D. DON cones and E. globulus capsules, bonded with a bio‐based polyurethane adhesive, for the manufacture of novel particleboards. This research opens the possibility of an alternative use for the pine cones and Eucalyptus capsules as a new prime source for the manufacture of particleboards and other composite materials. [ABSTRACT FROM AUTHOR]

With increasing concerns about the production of sustainable materials, the field of wood-based materials still offers a critical challenge. Indeed, a close dependence on petroleum derivatives is still required, involving high consumption of non-renewable and toxic chemicals in the assembly of wooden parts. Herein, the aim of this research was to evaluate the potentiality of an entirely renewable tannin-based adhesive for particleboard production. Industrial quebracho (Schinopsis balansae) tannin powder was selected as a raw material and analyzed in terms of polyphenols, polysaccharides, and the total condensed amount. Furfural was proposed as a bio-sourced hardener to establish crosslinking between the flavonoid units and hence produce a resin. This formulation was analyzed in terms of viscosity and curing time and then applied to laboratory-scale single-layer particleboard production. The density, mechanical properties, and thickness swelling of the panels were investigated at different glue ratios and pressing conditions. It was observed that time has a higher impact than temperature on the internal bond, and panels pressed at 160 °C for a longer pressing time (>7 min) performed better than the boards obtained at a higher temperature. The registered values at 160 °C for 11 min of pressing of internal bond (0.37 MPa) and modulus of elasticity (1417 MPa) met the required standards for P1 panels according to European norms EN 312 (2010). Conversely, the modulus of rupture (4.9 MPa) did not satisfy the requirements suggesting the need for the use of additive or post-treatments. Considering the results achieved, quebracho–furfural adhesives are an interesting base for bio-based adhesive formulations. [ABSTRACT FROM AUTHOR]

Lignin is produced worldwide in pulp mills and is currently mainly used for energy recovery. Because of its chemical properties, one possible utilisation is the production of lignin-based materials. Currently, developed lignin-based adhesives are based mainly on lignosulfonate instead of kraft lignin since lignosulfonate is more reactive than kraft lignin. However, worldwide substantially more kraft lignin is produced. The presented research deals with the development of resin chemically modified with kraft lignin up to 40% (w/w) content of kraft lignin. The synthesis of adhesives is described, and developed adhesives are characterised. Namely, viscosity, mechanical properties of resins and results of differential scanning calorimetry are presented. Furthermore, the developed kraft-lignin-based adhesives were used for the production of particleboards. Pre-pressing in a cold press followed by hot pressing in a laboratory press was used for the production of particleboards. The physical (thickness swelling, moisture uptake, vertical density profile), as well as mechanical (internal bonding, modulus of rupture, modulus of elasticity in three-point bending) properties of particleboards, were evaluated. The results clearly show that kraft lignin can be used for the production of lignin-based adhesives for the production of particleboards. [ABSTRACT FROM AUTHOR]

The utilization of soy protein as a wood adhesive has been successfully implemented in the industrial production of plywood. However, it is still a significant challenge to directly utilize soy protein-based adhesive for the fabrication of particleboard owing to its high viscosity and low cold tack. In this study, polyvinyl acetate (PVAc) emulsion was used to modify soy protein-based adhesive to reduce its viscosity and enhance its cold tack. By incorporating a content of 30% PVAc emulsion, the viscosity of the adhesive was reduced to 880 mPa·s, which was much lower than the pure soy protein-based adhesive value. Simultaneously, the cold tack was significantly increased by nearly 500 times after the addition of PVAc. The obtained adhesives met the requirements for particleboard production. In addition, the internal bonding strength of the produced particleboard reached 0.7 MPa, significantly exceeding the requirements for P6-grade particleboards (≥ 0.40 MPa, GB/T4897–2015). Moreover, it exhibited no formaldehyde emissions, making it a high-quality particleboard suitable for furniture applications. This study successfully presents a soy protein-based adhesive suitable for particleboard production using a simple blending modification approach, thereby expanding the application scope of soy protein-based adhesives. [Display omitted] • A lower viscosity and higher cold tack of soy protein-based adhesive was developed by simply adding PVAc. • A novel and simple testing method has been developed to assess the cold tack performance of adhesives. • The prepared composite adhesive can be directly applied in the production of particleboard. [ABSTRACT FROM AUTHOR]

This research aimed to evaluate particleboards produced with bean straw and rubberwood particles glued with vegetable polyurethane adhesive as a proposal for a sustainable insulating material. Therefore, the physical, chemical, and mechanical properties of the panels were determined, as well as their resistance to termite attack, combustibility, and thermal insulation. By increasing the bean straw particle content, the water absorption was significantly reduced (from 11.44 % to 7.68 %), with the same tendency observed for thickness swelling (from 4.61 % to 1.73 %) after 24 h of immersion. Panels produced with 25 and 75 % bean straw contents showed an end to thermal degradation before rubberwood-only compounds, being more resistant to combustion. There was a reduction in the modulus of elasticity (66.4 %) and modulus of rupture (52.5 %) due to the increase in the bean straw particle content. The evaluation of the resistance of the particleboard to dry wood termites showed a lower mass loss for composite panels with higher contents of bean straw. The thermal conductivity of particleboards showed that greater amounts of waste resulted in greater thermal insulation. In terms of generating sustainable products and meeting the needed properties, it was concluded that it is feasible to produce particleboards with agricultural wastes and formaldehyde-free adhesive. • Bean wastes were used as a substitute for rubberwood in particleboards. • Particleboards with environmentally friendly castor oil-based adhesive were studied. • The chemical properties of bean wastes influenced the properties of particleboards. • The thermal insulation of the panels improved with higher waste levels. [ABSTRACT FROM AUTHOR]

Waste particleboard is a valuable feedstock for the particleboards. Recycling waste panels into particleboard is hindered by adhesive residues in the particles. This study aims to investigate the effect of adhesive residues on the physical and mechanical properties of particleboard. The chemical properties and wettability of particles containing pMDI and UF residues were investigated, and these particles were further used to produce particleboards. Results revealed that the pMDI residue is incompatible with fresh UF resin and forms weak bonding in the particleboards. However, the pMDI residue can continue to react with the fresh pMDI and form strong adhesion. The UF residue cannot cross-linked with the fresh UF, and the additional hydrophilic groups, resulting in a severe reduction in the dimensional stability of the panels, but the decrease in the mechanical properties is not significant. Interestingly, the UF residue promotes the curing of fresh pMDI, thus benefiting the mechanical properties of the panels. This study can guide the selection of adhesives in producing recycled particleboard using waste particleboard, thereby promoting the efficient recycling of waste particleboard. • The interactions between residual and fresh adhesives were analyzed. • The pMDI residue is incompatible with fresh UF resin. • Both pMDI and UF residues can react with fresh pMDI to promote its curing. [ABSTRACT FROM AUTHOR]

In the context of natural resource scarcity, environmental challenges and human health concerns, the development of alternative solutions becomes crucial to sustainable development. Sustainable and renewable protein-containing materials such as soy or canola have proved to have wood bonding properties comparable to those of synthetic binders. In addition, the availability of canola meal offers a great possibility for the development of bio-adhesives for the wood-based panel industry. Furthermore, direct utilization of canola meal helps to avoid expensive and low-yield protein isolation processes. Using three different solvent solutions (water and 1 mol and 2 mol sodium hydroxide), canola-based bio-adhesives were prepared and used for the production of medium-density fiberboards (with 10 mm thickness and 800 kg/m3 target density) and three-layer particleboards (with 15 mm thickness and 640 kg/m3 target density). The produced boards were tested for their mechanical properties and dimensional stability according to European norms. With the MDFs' bending strength values above 40 N/mm2 and internal bonding strength greater than 0.5 N/mm2, the results show that there is indeed a possibility to achieve good mechanical properties using canola meal as a binder. The use of NaOH solutions as denaturants, as well as the addition of colasol, helped improve the bonding properties of the boards by 35.49% and 64.52% for 1 mol and 2 mol NaOH solutions, respectively. The obtained results show that the developed canola-based bio-adhesive can compete with conventional ones. However, despite the good mechanical properties of the produced boards, their poor dimensional stability due to the low water resistance of natural proteins suggests further improvement for industrial application. [ABSTRACT FROM AUTHOR]

Rice is one of the most common stable foods that is consumed globally with 680 million tonnes being grown annually worldwide. With its cultivation, an associated increase in waste generation to about 120 and 1.8 million tonnes from both rice husk and groundnut processing activities have been reported, respectively. Therefore, it is expedient to find meaningful methods of utilizing these wastes in the society. The study investigates the possibility of experimentally producing panelboards from agricultural wastes using modified adhesive system. Agricultural wastes from groundnut shell (GS) and rice husk (RH) were processed into particles and utilized in the production of the composite panelboards. Variations of 30–70, 70–30, 50–50% for GS–RH and 100% for each of the waste materials were adopted. Dimensional stability tests, density, internal bond, modulus of elasticity (MOE) and modulus of rupture (MOR) properties were determined according to EN 312-2 and 312-3 standards. The results showed that the dimensional stability values were below the maximum requirement of 8% after 24 h immersion in water. The highest density and internal bond strength of 0.98; 0.97 g/cm3 and 0.24; 0.23 N/mm2 were obtained from samples made from 30% RH + 70% GS and 50% RH + 50% GS, respectively. The best mechanical performance was achieved at 122.79 and 1.91 MPa from samples produced from 30% RH + 70% GS, respectively. The mechanical properties did not conform to the same standard because it fell short of the minimum requirements. The produced panelboards from rice husk and groundnut shell wastes could be used in developing eco-friendly interior panelboard materials. [ABSTRACT FROM AUTHOR]

Toxic formaldehyde emissions, and the necessity to reduce the consumption of petrochemicals, stimulates the development of environmentally friendly adhesives. The aim of this research was to study, for the first time, the possibility of using condensed tannins (CTs)-rich extracts from grey alder (Alnus incana) and black alder (Alnus glutinosa) bark in the production of particleboards and plywood adhesives. The chemical structure, composition, and molecular weight of the CTs were identified by a 13C-NMR and TOF-MS analysis. Three innovative adhesive systems were studied: CTs-phenol-formaldehyde (CTs-PF) resin; a CTs-polyethyleneimine (PEI) adhesive system; and CTs–PEI combined with an ultra-low emitting formaldehyde resin (ULEFR)—CTs–PEI–ULEFR. The results showed that CTs-PF resin has properties close to commercial PF resin, and the formaldehyde emission was twice lower. CTs–PEI bonded particleboards corresponded to the requirements of the EN 312:2010 standard for particleboards in dry conditions (Type P2). CTs–PEI–ULEFR, with a 40–60% substitution of ULEFR by CTs–PEI, had adhesive properties very close to ULEFR; the plywood shear strength fit the requirements of the EN 314-2:1993 standard for application in internal and external system conditions. The introduction of extracted alder bark residues microparticles into the composition of the adhesive system showed their positive potential for application as a filler. [ABSTRACT FROM AUTHOR]

The birch (Betula spp.) outer bark is a valuable product rich in betulin. After removal of betulin extractives, suberin containing tissues are left. Suberin is a biopolyester built from α,ω-bifunctional fatty acids (suberinic acids), which after depolymerization together with lignocarbohydrate complex is a potential adhesive as a side-stream product (residue) from obtaining suberinic acids for polyol synthesis. In this work, we studied the utilization possibilities in particleboards of the said residue obtained by depolymerization in four different solvents (methanol, ethanol, isopropanol and 1-butanol). The adhesives were characterised by chemical (acid number, solubility in tetrahydrofuran, epoxy and ash content) and instrumental analytical methods (SEC-RID, DSC, TGA and FTIR). Based on the results of mechanical characteristics, ethanol was chosen as the most suitable depolymerization medium. The optimal hot-pressing parameters for particleboards were determined using the design of experiments approach: adhesive content 20 wt%; hot-pressing temperature 248 °C, and hot-pressing time 6.55 min. [ABSTRACT FROM AUTHOR]

Adhesives represent an important part in the wood-based composite production, and taking into account their impact on the environment and human health, it is a challenge to find suitable natural adhesives. Starting from the current concerns of finding bio-adhesives, this paper aims to use magnesium lignosulfonate in three adhesive recipes for particleboard manufacturing. First, the adhesive recipes were established, using oxygenated water to oxidize magnesium lignosulfonate (Recipe 1) and adding 3% polymeric diphenylmethane diisocyanate (pMDI) crosslinker (Recipe 2) and a mixture of 2% polymeric diphenylmethane diisocyanate with 15% glucose (Recipe 3). The particleboard manufacturing technology included operations for sorting particles and adhesive recipes, pressing the mats, and testing the mechanical strengths and formaldehyde emissions. The standardized testing methodology for formaldehyde emissions used in the research was the method of gas analysis. Tests to determine the resistance to static bending and internal cohesion for all types of boards and recipes were also conducted. The average values of static bending strengths of 0.1 N/mm2, 0.38 N/mm2, and 0.41 N/mm2 were obtained for the particleboard manufacturing with the three adhesive recipes and were compared with the minimal value of 0.35 N/mm2 required by the European standard in the field. Measuring the formaldehyde emissions, it was found that the three manufacturing recipes fell into emission classes E1 and E0. Recipes 2 and 3 were associated with good mechanical performances of particleboards, situated in the required limits of the European standards. As a main conclusion of the paper, it can be stated that the particleboards made with magnesium-lignosulphonate-based adhesive, with or without crosslinkers, can provide low formaldehyde emissions and also good mechanical strengths when crosslinkers such as pMDI and glucose are added. In this way magnesium lignosulfonate is really proving to be a good bio-adhesive. [ABSTRACT FROM AUTHOR]

Laboratory tests were carried out to evaluate the feasibility of producing particleboards with sugarcane bagasse and Eucalyptus sp. and adhesives (tannin pure and lignosulfonate (tannin + lignosulfonate in the proportion of 80:20)). The adhesives were characterized (pH, gel time, viscosity, and density), and the physical and mechanicals properties was realized (water absorption and thickness swelling, moisture content, gravimetric density, density profile by X-ray, elasticity and rupture modulus, and internal bond). The particleboards showed some homogeneity in density. As to the thickness swelling, the means varied from 24.15 % to 35.57 %, with higher averages for those particleboards that used lignosulfonate adhesive. The same effect could be seen in the water absorption test, with emphasis on the tannin-lignosulfonate adhesives, with averages 18.5 % higher than those of pure tannin, regardless of the type of material. Based on the internal bond test, the highlight was the treatment with 100 % wood particles and pure tannin adhesive. As sugarcane bagasse was added, there was a reduction in modulus of elasticity, independently of the adhesive used. The results highlighted the using lignosulfonate as a component obtained inferior results when compared to those of pure tannin, mainly concerning humidity and the internal bond test. As well as a gradual loss of strength as the wood was replaced by sugarcane bagasse. In this aspect, environmental issues are gained as waste is used; in such uses, such properties are not required. [ABSTRACT FROM AUTHOR]

Magnesium oxychloride adhesive (MOA) is a kind of inorganic adhesive with a low energy consumption and environmental protection. The modified particleboard with magnesium oxychloride adhesive (MOPB) has the advantages of no volatiles and has a high mechanical strength. In this study, MOA and poplar shavings were used to prepare MOPB, fly ash (FA) was used to modify and enhance the properties of MOPB; the influence mechanism on the mechanical of MOPB was studied. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to analysis the bonding mechanism of MOA and poplar shavings, and the composite system model of MOPB was constructed. The mechanism of modified MOPB with FA (MOPB-FA) was clarified. The results show that the use of FA effectively improved the mechanical strength of MOPB, and when the ratio of FA addition was 15 wt%, MOPB-FA's modulus of rupture (MOR) value was 16.32 MPa, an increase of 24.5% more than before (13.11 MPa). The modulus of elasticity (MOE) value was 4595.51 MPa, an increase of 76.7% more than before (2600 MPa), and the thickness of swelling (TS) value was 0.35%, a decrease of 85.2% less than before (2.36%). [ABSTRACT FROM AUTHOR]

ABSTRACT spp. wood trunks were processed into 1.0 gcm−3 particleboards at three different particle sizes with the addition of natural adhesives, i.e. soy flour and lignin. Samples of particleboards were characterized using scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Crystallinity evaluation was conducted via X-ray diffraction (XRD). SEM images of the 6% adhesive-bonded Rhizophora spp. showed improvement in terms of compactness and number of voids, compared to the binderless sample. SEM images of soy flour appeared bright due to its higher density compared to lignin. FTIR spectrum of Rhizophora spp., soy flour, and lignin, were in good agreement with the previous study with adhesive-bound samples showed no discernible difference compared to raw Rhizophora spp. sample. TGA analysis revealed that all the samples showed a dissociation temperature of below 450°C. XRD result implies a lower crystallinity index compared to previous studies, indicating more amorphous material existed in the sample than crystalline material thus suggesting better physical and mechanical strength. Overall results demonstrated the potential use of soy-lignin bonded Rhizophora spp. particleboard as a tissue-substitute phantom material in medical physics applications. [ABSTRACT FROM AUTHOR]

In this work, a novel way is proposed to produce an eco‐friendly and formaldehyde‐free particleboard (PB) panel from agro‐industrial residues bonded with natural rubber latex (NRL)‐based adhesive. Polyvinyl alcohol (PVOH) was added as an adhesion promoter and polymeric 4,4‐methylene diphenyl diisocyanate (pMDI) was used as cross‐linker. Different formulations of agro‐industrial residues (cassava stem, sengon wood waste, and rice husk) and different contents of NRL‐adhesive (10%, 15%, and 20%) were applied to prepare the PB panel. Several techniques were performed to characterize the properties of NRL‐based adhesive and to evaluate the performance of PB panels from agro‐industrial residues bonded with NRL‐based adhesive. The blending of NRL and PVOH resulted in weak hydrogen bonds in the polymer blends. Incorporation of pMDI provided NCO groups as the reactive site for cross‐linking with NRL‐PVOH via urethane linkages. The results showed that no remarkable differences in the physical properties of the PB panel, such as density, moisture content, water absorption, and thickness swelling, with different agro‐industrial residues formulations and NRL‐adhesive content. By contrast, greater NRL‐adhesive content affected the mechanical properties of the PB panel. The best mechanical properties of the PB panel were obtained using a formulation of 40% of cassava stem, 30% of sengon wood waste, 30% of rice husk, and bonded with 20% of NRL‐adhesive content, which resulted in 4.02 MPa of modulus of rupture (MOR), 441.00 MPa of modulus of elasticity (MOE), and 0.19 MPa of internal bonding (IB) strength. A combination of agro‐industrial residues particles and NRL‐based adhesive presented a high potential for application as an eco‐friendly, formaldehyde‐free, and non‐structural PB such as interior applications. [ABSTRACT FROM AUTHOR]

Maltodextrin is a potential natural adhesive for particleboard because it is reactive and freely soluble in water. However, maltodextrin has a low water resistance and a high melting point that hinder its development as a particleboard adhesive. An addition of ammonium dihydrogen phosphate (ADP) as a catalyst of maltodextrin was expected to overcome its weaknesses. The optimal pressing temperature was expected to be affected due to the addition of catalysts. This research aimed to investigate the effect of maltodextrin/ADP ratios and pressing temperatures on particleboard properties made from Salacca frond. The maltodextrin/ADP ratios used in this research were 100/0, 90/10, and 80/20 wt%, and the pressing temperatures were set at 200 and 220 °C. The combination of an increased ADP ratio in maltodextrin and an increased pressing temperature improved the particleboard properties. The water resistance was also significantly improved by addition of ADP and increased pressing temperature. Thermal analyses showed that the onset temperature of weight reduction of maltodextrin added particles was lowered by addition of ADP. The results suggested that a maltodextrin/ADP mixture could be a promising particleboard binder. [ABSTRACT FROM AUTHOR]

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The aim of this research was to evaluate the potential of magnesium lignosulfonate as adhesive in particleboard manufacturing. Diphenylmethane diisocyanate (PMDI) between 1% and 3% and glucose (1% of the lignosulfonate content) were added as potential cross-linkers in the adhesive formulations. Mixed beech and spruce wood, 30% beech wood and 70% spruce wood, were employed for the configuration of the panel structure. The density, mechanical properties and formaldehyde emission of single-layer particleboard were investigated. Spectroscopic analysis (FTIR) revealed structural changes brought by oxidation that may indicate depolymerization by the splitting of C-O-C bonds and formation of carbonyl groups. Mechanical properties were improved, and the highest average values were recorded for panels having as adhesives oxidized lignin with cross-linkers as follow: 15 N/mm2 (MOR), 3320 N/mm2 (MOE) and 0.48 N/mm2 (IB). The density profile presented higher values for faces in case of oxidized lignin panels. Changes were observed for oxidized lignin with cross-linker panels wherein the core had higher values. The results showed that the panels manufactured with adhesives composed of oxidized lignosulfonate (20% of the dried wood particles weight) and the addition of PMDI and glucose in various percentages have a positive influence on their formaldehyde release and mechanical properties requested by EN 312 (2004) standard. [ABSTRACT FROM AUTHOR]

Wood-based panels are commonly used as building materials for interior and exterior purposes. Their production and utilization have increased in recent decades due to the useful properties that they present. Adhesive-bonded products comprise up to 80% of the wood alternatives on the global market, and of that, urea–formaldehyde (UF) makes up approximately 81% of the resins used. To improve UF performance, the utilization of microfibrillated cellulose has been demonstrated to be effective. However, further understanding of the mechanisms of the interactions is of relevant importance. In this work, we studied interfacial interactions between UF with bleached (BCNFs) and unbleached (LCNFs) cellulose nanofibrils using Quartz Crystal Microbalance with dissipation monitoring (QCM-D) technique, observing the superior performance of lignin-containing CNFs. Additionally, the surface free energies were investigated using contact angle (CA) measurements, showing a decrease of the values mainly when utilizing LCNFs, which was later correlated with the wettability properties of the PBs. PBs with different adhesive/CNF formulations were produced, showing larger improvements when adding LCNF in terms of modulus of elasticity (MOE), modulus of rupture (MOR), and internal bonding (IB). To gain a better understanding of the interactions between CNFs and UF, both CNFs were fully characterized in terms of morphology, chemical composition, charge density, as well as thermal and colloidal stability. [ABSTRACT FROM AUTHOR]

Formaldehyde-based resins are commonly used in the particleboard industry due to their high bonding strength and excellent water resistance. Nowadays, the healthy and sustainable issues lead to the development of bio-based wood adhesives. In the last past decade, soybeans were the most prominent crop for the production of environmentally friendly adhesive with no formaldehyde in its composition. This review covers the strengths, weaknesses, opportunities and threats of soy-based adhesives as a replacement of conventional resins. Moreover, this work details the different techniques used to improve the performance of soy protein adhesives in order to encourage their use in the wood industry. [ABSTRACT FROM AUTHOR]