Polyurethane Adhesives Research Articles

Nano-SiO2 based anti-corrosion superhydrophobic coating on Al alloy with mechanical stability, anti-pollution and self-cleaning properties

Improving the corrosion resistance of widely used Al alloys is important for expanding their industrial and marine applications. Structural fragility and preparation cost have always been key factors for restricting anticorrosive application of extensively-reported superhydrophobic surface. In order to try and fight that, combining with polyurethane (PU) adhesion agent, 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) was encapsulated around nano-SiO2 ceramics for robust coating in place of conventional structure preparation strategy on Al alloy surface. Such low-cost one-step air-spraying SiO2@PFDTES@PU coating was prepared by 0.03 g nano-SiO2 ceramics addition, 100 μL PFDTES and 0.25 g PU with the highest water contact angle of 168.34° ± 2.72°, a rolling angle of 4.02° ± 2.08°, and a propylene glycol oil contact angle of 156.52° ± 3.35°. FE-SEM, laser confocal microscopy, EDS and XPS were used to investigate micro-nano morphology and chemical composition of the coating. Meanwhile, the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements showed that as-prepared coating exhibited larger capacitive arc diameter, enhanced charge transfer resistance, larger |Z|0.01Hz value, positive shifting Ecorr and significantly reduced Icorr, thus demonstrating a significantly improved corrosion resistance. In addition, sandpaper friction experiment was used to evaluate the mechanical stability of the fabricated superhydrophobic coating. Ultimately, its resistance to solid/liquid contamination and self-cleaning ability were also systematically assessed. This work provides strong technical supports for industrial and marine applications for such low-cost, wear-resistant and anti-corrosion coating.

Hemp fiber reinforced dual dynamic network vitrimer biocomposites with direct incorporation of amino silane

Natural fiber composites are inexpensive and renewable alternatives to traditional fiber reinforced polymers (FRPs). However, existing natural fiber composites primarily rely on petrochemical based thermosetting matrices, which are difficult to recycle due to their stable crosslinked network structures. To address this challenge, it is desirable to develop natural fiber composites with inherently recyclable biobased matrices. In this study, we developed a dual dynamic network vitrimer matrix from hempseed oil and limonene derivatives and demonstrated its application in hemp fiber reinforced composites. To improve the weak interface between hemp fiber and the polymer matrix, a common challenge in the realm of natural fiber composites, we directly incorporated amino silane into the vitrimer matrix. The amino silane participated in the polymer network, increasing the crosslink density and toughening the matrix, as evidenced by the significant improvement of impact strength from 3.5 kJ/m2 to 10.3 kJ/m2. Moreover, the incorporation of amino silane resulted in a lower water absorption by 11 % in a 7-day soaking for the composites, demonstrating improved fiber/matrix interfacial interaction. Furthermore, our biobased vitrimer matrix exhibits both imine and hydroxy-ester dynamic bonds, which enable the recycling of the biocomposite through a mild and cost-effective aminolysis process (100 °C, 3 h, ambient pressure). The decomposed polymer matrix was successfully reused as a polyol for polyurethane adhesives, and the surface morphology of recovered hemp fibers was analyzed and compared with that of the original fibers. These findings will help broaden the use of vitrimers for practical natural fiber composite applications, raise awareness of the problem of recycling natural fiber composite waste, and shed light on the interfacial challenge of natural fiber reinforced vitrimer composites.

Silane Effects on Adhesion Enhancement of 2K Polyurethane Adhesives.

With excellent properties such as great flexibility, outstanding chemical resistance, and superb mechanical strength, two-part polyurethane (2K PU) adhesives have been widely applied in many applications, including those in transportation and construction. Despite the extensive use, their adhesion to nonpolar polymer substrates still needs to be improved and has been widely studied. The incorporation of silane molecules and the use of plasma treatment on substrate surfaces are two popular methods to increase the adhesion of 2K PU adhesives, but their detailed adhesion enhancement mechanisms are still largely unknown. In this research, sum frequency generation (SFG) vibrational spectroscopy was used to probe the influence of added or coated silanes on the interfacial structure at the buried polypropylene (PP)/2K PU adhesive interface in situ. How plasma treatment on PP could improve adhesion was also investigated. To achieve maximum adhesion, two methods to involve silanes were studied. In the first method, silanes were directly mixed with the 2K PU adhesive before use. In the second method, silane molecules were spin-coated onto the PP substrate before the PU adhesive applied. It was found that the first method could not improve the 2K PU adhesion to PP, while the second method could substantially enhance such adhesion. SFG studies demonstrated that with the second method silane molecules chemically reacted at the interface to connect PP and 2K PU adhesive to improve the adhesion. With the first method, silane molecules could not effectively diffuse to the interface to enhance adhesion. In this research, plasma treatment was also found to be a useful method to improve the adhesion of the 2K PU adhesive to nonpolar polymer materials.

Durability assessment of one-component polyurethane adhesives for bonding of preservative treated wood subject to artificial ageing

Advancements in the use and applications of engineered wood products is receiving much interest in the construction industry. This is because wood has highly credible characteristics in relation to sustainability. It acts as a carbon store and is a natural renewable material. However, achieving adequate durability requirements and ensuring satisfactory adhesive bondline integrity is fundamental for such engineered products particularly when subjected to an exposed exterior service class environment. Little information exists on the durability performance of preservative treated wood bonded using one-component polyurethanes (1C-PURs). This study therefore involved the accelerated ageing of two 1C-PUR adhesives for the bonding of untreated, copper chromate arsenic and micronised copper azole preservative treated wood of fast growing Radiata pine. The ageing involved both vacuum-pressure soak drying cycling and exposure to a constant long-term high temperature and humidity environment. Resorcinol formaldehyde bonded specimens and solid wood specimens were used as controls. The testing showed that the standard requirements for delamination were satisfied when bonding preservative treated wood with 1C-PUR adhesive. The shear strength of specimens bonded with 1C-PUR adhesive subjected to vacuum-pressure soak drying compared well to the performance of the controls. The predominant failure behaviour was wood failure. The shear strength of all bonded preservative treated wood specimens with both 1C-PUR and resorcinol formaldehyde which were exposed to a constant long-term high temperature and humidity environment demonstrated a general and comparable reduction in strength over time which was statistically significant. High wood failure percentages were recorded at the bond interface which indicated weakening of the wood adherend when subject to the ageing rather than weakening of the adhesive bond. Chemical analysis of bonded specimens after ageing demonstrated that no significant variations were experienced.

Synthesis and characterization of sesame oil based plasticizers for reversible bonding in thermally detachable polyurethane adhesives

Permanent adhesion causes immense problem during repairing of expensive components in electronics and automotive industries. Adhesives that can be reversibly debonded upon stimulus are a popular solution to this issue in the present day. Here, we report the synthesis of an eco-friendly polyurethane hot-melt detachable adhesives (HMDA) that uses oxime-carbamate bonding and is derived from natural and modified polyols from sesame seed oil. With the help of catalyst dibutyltin dilaurate (DBTDL), polyols and dimethyl glyoxime has been polymerized with toluene diisocyanate (TDI) and glycerin. FTIR, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) have been used to analyze prepared adhesives. Out of prepared samples, a very minute amount of hydroxylated sesame oil based sample (S3) has shown good binding strength with glass surface, having load capacity of 200 g/12 h and can be used repeatedly for >20 cycles.

Preparation and properties of high molecular weight high temperature resistant carborane polyurethane adhesive

The long-term use temperature of the traditional high-temperature adhesive can only reach about 280 °C, and it cannot be used in extreme environments such as acid and alkali for a long time, which greatly limits its application in aerospace and other fields. Because of its unique three-dimensional structure, carborane has excellent thermal stability and chemical stability. Based on this, first, this article introduced carborane monomer into polyurethane structure, using indirect copolymerization method, Hydroxyl carborane derivative (m8) and conventional polyether diols were used as soft segments. By adjusting the introduction ratio of m8, a series of copolymerized carborane polyurethane (Co-CBR-PU) with controllable thermal and mechanical properties were successfully prepared. Its structure and molecular weight were characterized by FTIR and gel permeation chromatography (GPC), its surface morphology were observed by SEM. The thermal stability and mechanical properties were studied by thermogravimetric test, tensile test and rheological dynamic mechanical analysis test., and its activity, solvent resistance and hydrophobic properties were studied by finger contact method, solvent resistance test and contact Angle test. Second, the high temperature resistant carborane polyurethane adhesive (PUAS) was prepared using Co-CBR-PU as matrix and its adhesion was studied. The results show that a series of Co-CBR-PU has good high temperature resistance, mechanical properties and solvent resistance after adding carborane monomer, and its various properties were optimal when the addition amount of m8 was 15 wt%. The carborane PUAS prepared by using it as the substrate has excellent high temperature adhesion to different adhesive parts. The aim of this study is to reduce the cost of synthesis of carborane polyurethane by regulating the proportion of carborane, and then realize the industrial trial production of high temperature resistant carborane adhesive.

Reactive polyurethane hot-melt adhesives with high biogenic carbon content

ABSTRACTThe use of water-based or solvent-based polyurethane adhesives is widely extended in the footwear industry. However, reactive polyurethane hot-melt adhesives (RPHMA) represent a good option to substitute both technologies as they are solvent-free. Their environmental footprint can be further improved with the use of renewable raw materials for their synthesis. A typical RPHMA formulation includes macroglycols and isocyanates as raw materials, both of which are based on petroleum derivatives. Against this background, this work focuses on the development of RPHMAs based on polyols from renewable sources, which considerably improves their content in biogenic carbon. The evaluation of the new adhesives properties was conducted using different experimental techniques such as FTIR, TGA, DSC, CLSM, XRD, plate-plate rheometry, R&B softening point, biogenic carbon content (ASTM D6866–22, method B) and T-peel strength of adhesive joints (EN 1392:2007), before and after aging. The partial substitution of one of the conventional petroleum-based polyols by a bio-based polyol leads to a change in the segmented structure of polyurethane and an increase in the polyurethane thermal resistance and crystallinity. Furthermore, the new adhesives based on reduced fossil content meet the standard quality requirements on adhesive properties for footwear, according to EN 15,307:2015.

Towards reducing the capital cost of manufacturing Laminated Veneer Lumbers: Investigating finger jointing solutions

The capital cost of setting up a Laminated Veneer Lumber (LVL) plant which produces continuous LVL billet products, through a continuous veneer assembly and hot-pressing processes, is significant. However, the utilisation of batch-type presses, similar to those employed in the plywood industry, could significantly reduce this initial cost and may provide new opportunities for small to medium scale operations. This process would produce shorter billet lengths which would need to be joined together to produce lengths viable for structural products. Scarf joints have been used commercially to join some veneer-based engineered wood products but have limitations, while finger joints are a common method for jointing sawn timber products and offer some key advantages but is not a common method to join veneer-based products. Consequently, this paper focusses on investigating the influence of key manufacturing parameters on the performance of finger jointed LVL. The effect of the joint orientation (horizontal or vertical), the finger length, the gluing pressure and the adhesive type on the joint strength and stiffness were investigated. The finger jointed LVL were tested in edge bending, flat bending and tension, and the results were compared to reference unjointed LVL. The bending performance of the finger jointed LVL was also compared to scarfed jointed LVL. In total 304 tests were performed. The results indicated that the average strength values of finger jointed LVL can reach up to 99% of the average strength of unjointed LVL and compares to scarf jointed LVL on flat bending. Horizontal joints, being more practical to produce for deep beams, performed similarly to vertical joints. The 25 mm joints were found to have no mechanical advantages over the 20 mm investigated finger joints. A gluing pressure lower than the Eurocode's recommended level for solid timber achieved sufficient bonding for the products to be utilised. The gluing pressure was also found not to influence the performance of the joint, for the range of pressures investigated. Both polyurethane and resorcinol-formaldehyde adhesives produced high performing products, with the latter displaying superior adhesive bond durability. The paper concludes that finger jointing LVL represents a viable solution to manufacture usable LVL lengths from short LVL billets, but have lower edge bending efficiency than scarf jointed LVL.

Polyurethane Adhesives for Wood Based on a Simple Mixture of Castor Oil and Crude Glycerin

Developing a new type of polyurethane is essential because conventional options often exhibit shortcomings in terms of environmental sustainability, cost-effectiveness, and performance in specialized applications. A novel polyurethane adhesive derived from a simple mixture of castor oil (CO) and crude glycerin (CG) holds promise as it reduces reliance on fossil fuels and harnesses renewable resources, making it environmentally friendly. Simple CO/CG mixtures, adjusted at three different weight fractions, were used as bio-based polyester polyols to produce polyurethane adhesive for wood bonding. The resulting products are yellowish liquids with moderate-to-high viscosity, measuring 19,800–21,000 cP at 25 °C. The chemical structure of the polyester polyols was characterized using infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). These polyols reacted with polymeric 4,4-methylene diphenyl diisocyanate (p-MDI) at a consistent isocyanate index of 1.3, resulting in the formation of polyurethane adhesives. Crucially, all final adhesives met the adhesive strength requirements specified by ASTM D-5751 standards, underscoring their suitability for wood bonding applications. The addition of CG enhanced the surface and volumetric hydrophobicity of the cured adhesives, resulting in adhesive properties that are not only stronger but also more weather-resistant. Although the thermal stability of the adhesives decreased with the inclusion of CG, FTIR analysis confirmed proper polyurethane polymer formation. The adhesive adjusted for a 2:1 CO:CG weight ratio promoted wood–wood bonding with the highest shear strength, likely due to a higher formation of urethane linkages between hydroxyl groups from the blend of polyols and isocyanate groups from the p-MDI.

Polyurea-Graphene Nanocomposites-The Influence of Hard-Segment Content and Nanoparticle Loading on Mechanical Properties.

Polyurethane and polyurea-based adhesives are widely used in various applications, from automotive to electronics and medical applications. The adhesive performance depends strongly on its composition, and developing the formulation-structure-property relationship is crucial to making better products. Here, we investigate the dependence of the linear viscoelastic properties of polyurea nanocomposites, with an IPDI-based polyurea (PUa) matrix and exfoliated graphene nanoplatelet (xGnP) fillers, on the hard-segment weight fraction (HSWF) and the xGnP loading. We characterize the material using scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). It is found that changing the HSWF leads to a significant variation in the stiffness of the material, from about 10 MPa for 20% HSWF to about 100 MPa for 30% HSWF and about 250 MPa for the 40% HSWF polymer (as measured by the tensile storage modulus at room temperature). The effect of the xGNP loading was significantly more limited and was generally within experimental error, except for the 20% HSWF material, where the xGNP addition led to about an 80% increase in stiffness. To correctly interpret the DMA results, we developed a new physics-based rheological model for the description of the storage and loss moduli. The model is based on the fractional calculus approach and successfully describes the material rheology in a broad range of temperatures (-70 °C-+70 °C) and frequencies (0.1-100 s-1), using only six physically meaningful fitting parameters for each material. The results provide guidance for the development of nanocomposite PUa-based materials.

Analysis of Resistance to Wind Suction of Flat Roof Coverings Glued with Polyurethane Adhesives.

The article analyses the impact of wind suction on roof coverings glued with polyurethane adhesives to flat roofs, i.e., roofs with an up to 20% slope. The impact of the cyclical wind was simulated in fatigue tests, gradually increasing the test pressure in repeated sequences until the first delamination occurred. The tests were carried out for eight test sets, with concrete and trapezoidal sheets used as a construction substrate, on whose surface thermal insulation layers were glued with polyurethane adhesive; the thermal insulation layers were EPS (expanded polystyrene) and PIR (polymer mainly of polyisocyanurate groups), respectively, followed by flexible sheets, i.e., a laminated PVC membrane (polyvinylchloride) and an EPDM (terpolymer of ethylene, propylene and a diene with a residual unsaturated portion of diene in the side chain)-type rubber-based membrane. The test results were compared with the functional requirements determined with computational simulation methods for the maximum wind load values on the example of wind loads for Poland. The tests confirmed that some polyurethane adhesives could ensure the operation of flexible sheets used as flat roof coverings that are failure-free from the point of view of resistance to wind suction.

Open time studies of cold curing polyurethane adhesives using a standardized spatula test setup suitable for near-production conditions

The presented studies introduce a new set-up and method to analyse the maximum open time of cold curing adhesives in a production environment. By using this new set-up, a manual spatula test, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and a rheological method, the curing reaction of two cold curing two component polyurethane adhesives, were investigated. Furthermore, the effect of different joining times on the bonding behaviour were investigated using single lap shear samples.The lap shear tests showed that the prior problem for industrial applications is the dimensional accuracy rather than the adhesion to the substrates as all samples showed cohesive or substrate near cohesive failure even when joined after the maximum open time. All used methods showed a coherent curing behaviour for both adhesives. However, the derived times as well as their accuracies vary depending on the used method. Using the easy manual spatula test, the open time is determined by the sensory feelings of the testing person while pressing a wooden spatula into the adhesive bead and is often used in industrial applications. However, the accuracy lies only within 10–20 s especially for slow curing adhesives. In comparison, the ATR-FTIR method, which is based on the decrease of the isocyanate group during the reaction, showed shorter times, whereas longer times were determined by observing the complex viscosity increase of the rheological measurements. Even though the ATR-FTIR and rheological measurements showed reproducible times due to the required laboratory environment and testing procedure, they are therefore not suitable for production conditions. As the introduced new method is based on the manual spatula test, it is suitable for the production environment with the advantage of a good reproducibility. Furthermore, with this method decreasing maximum open times were observed for increasing bead cross sections.

Experimental evaluation of interface adhesion of a flax fiber composite patch with epoxy and polyurethane adhesives for the reinforcement of steel structures

Using fiber-reinforced composite patches for repairing damaged structures made of metal or/and concrete is an interesting and widely available solution on the market using synthetic materials. These repairing patches are bonded on the structures’ surfaces to increase their strength against internal stresses, as well as protect them from external physico-chemical attacks, thereby limiting crack propagation. Natural fibers offer a potential alternative to replacing glass or carbon fibers commonly used for bonded repair patches. Similarly, bio-based polymers represent an important sustainable alternative for partially or entirely replacing the petroleum-based polymers. In this study, an epoxy matrix reinforced with flax fiber is proposed as the material for the patches, and bonded to a steel plate using four different types of adhesive materials, including a castor-oil derived polyurethane resin. Floating roller peel tests were performed to assess the adhesion and viability of these new patches. The resulting peeling loads and fracture surface analysis are presented. Polyurethane demonstrates promising performance for epoxy-to-steel joints, but major improvements of the bio-based polyurethane application process and curing conditions may be necessary for its successful industrial implementation.

Curing Kinetics and Structure-Property Relationship of Moisture-Cured One-Component Polyurethane Adhesives

Moisture-curable polyurethane (PU) adhesives have been exploited in the automotive industry because of their usability, non-toxicity without the use of volatile organic compounds (VOC), outstanding solvent resistance, and adhesiveness. However, there has been a lack of quantitative and comprehensive analyses related to the chemical and thermomechanical properties of moisture-curable PU adhesives depending on the applied curing conditions. Herein, we systematically investigated the effects of curing conditions, including relative humidities (25, 35, 45, 55, 65, and 75%RH) and curing duration (0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, and 7 days), on the structure–property relationships of moisture-cured PU adhesives. As the relative humidity increased, the chemical reaction of the PU adhesives accelerated, and they exhibited a high crosslinking density and storage modulus. However, even prolonged curing time and higher relative humidity did not lead to a continuous enhancement in the mechanical properties of the PU adhesive. After a sufficient curing time, the storage modulus of the PU adhesive reached saturation, and the PU adhesives cured above 65%RH demonstrated a comparable saturated storage modulus. This structure–property relationship of PU adhesives will provide fundamental understanding and insights for quality control and optimization of processing time in the industry.

Recyclable Wearable Sensor Based on Tough, Self-Healing, Adhesive Polyurethane Elastomer for Human Motion Monitoring

Recyclable Wearable Sensor Based on Tough, Self-Healing, Adhesive Polyurethane Elastomer for Human Motion Monitoring

Polymer nanocomposite adhesives with internal nano-heaters to facilitate multilayer laminate separation

Laminating adhesives used in multilayer films present strong, irreversible adhesion that limits the produced packaging systems to single-use applications. From a sustainability point of view, the recovery of individual polymers after use is imperative and a pivotal step is to make this adhesion reversible via breakdown of the adhesive structure. This work describes a promising strategy based on the incorporation of graphene into thermoreversible adhesive resin formulations to trigger the rupture of the adhesive network by exposure to IR radiation. Graphene is a thermal absorber that abruptly heats up under irradiation and efficiently dissipates this heat to the surrounding environment causing the adhesive network to collapse, resulting in remarkable changes in its mechanical properties. In this study, graphene was incorporated at low concentrations (0.25–1 wt %) into solvent-free polyurethane adhesives containing thermoreversible moieties. The photothermal effect at different loadings was evaluated and the formulation displaying the best balance between photothermal effect and optical properties was selected. Furthermore, the effect of irradiation on cyclability, fluidity and mechanical properties of the graphene-containing adhesives is evaluated. Good cyclability was observed and samples with a graphene loading of 0.25 wt % and 11.5 wt % of thermoreversible bonds (TRB) showed the largest difference in elongation under IR irradiation with respect to the neat adhesive. Creep testing demonstrated that the strain of this sample increases by almost 200% after irradiation due to the breakdown of the three-dimensional adhesive network triggered by the photothermal effect of graphene.

Ultrastrong and Versatile Nonisocyanate Polyurethane Adhesive under Extreme Conditions

Ultrastrong and Versatile Nonisocyanate Polyurethane Adhesive under Extreme Conditions

A novel green polyurethane adhesive based on castor oil and tannic acid with excellent water, salt, acid, alkali and antibacterial properties

In recent decades, solvent-free polyurethane adhesives from renewable sources are increasingly needed for engineering and biomedical applications. However, the significant drawbacks persist in bio-based polyurethane adhesives, including low moisture resistance, high sensitivity to variations in pH and salt, a sophisticated synthesis route, and costly adhesive building blocks. Inspired by the catecholic properties of mussel foot proteins, we used tannic acid as a crosslinker to strengthen the capabilities of castor-oil-based adhesives through a facile yet robust strategy. After directly mixing at room temperature, tannic acid was bonded with polyurethane prepolymer to construct a dual-network of noncovalent interaction and covalent crosslinks, hence improving the crosslinking density and cohesive connections. In addition, the adhesive and substrate interface interactions were strengthened. Owing to the diverse bonding abilities, the dry shear strength rose from 1.1 to 9.5 MPa. After immersing in water for 200 h, the largest wet shear strength was 5.2 MPa. Furthermore, this adhesive strength also increases at pH 2,12 and ionic strength of 0.2 M NaCl, demonstrating excellent adhesiveness (∼11.8 MPa). The easy-to-make adhesive also has outstanding bacterial resistance. The utilization of tannic acid and the formation of a dual network are a new strategy for developing green high-performance adhesives with biomass feedstock.

Bonding Performance of Melamine–Urea–Formaldehyde and Polyurethane Adhesives for Laminated Hybrid Beams and Their Selected Mechanical Properties

Beech (Fagus Sylvatica L.) is a prevalent tree species in Slovenia and is suitable for manufacturing glulam beams. However, beech wood has certain limitations that can potentially be mitigated by combining it with Norway spruce (Picea abies (L.) Karst.) wood to create hybrid beams. This study aimed to determine the bonding performance of commonly used melamine–urea–formaldehyde and polyurethane adhesives for these hybrid beams. Moreover, how varying the proportion of beech wood in a hybrid beam affects its mechanical properties was examined. Shear and delamination tests (method B) were conducted, and EN 14080:2013 requirements were met in all cases. The four-point bending tests of the beams showed that hybrid beams containing 20% of beech wood in the cross-sectional height on each side of the neutral axis exhibited a similar modulus of elasticity values as pure beech beams, but their strength was not equally improved. Hybrid beams with 11% of beech wood did not show any improvement in bending stiffness or strength compared to pure spruce beams. It was noted that the presence of beech wood in a hybrid beam can influence its failure mode. Furthermore, analytical calculations showed that a symmetrical lay-up is preferable to an asymmetrical one to increase the effective modulus of elasticity.

Joint Durability of Steam-Treated Beech Wood.

Steaming beech wood is one of the most commonly used eco-based processes for wood color equilibration. In addition to color equalization, steaming has also been noticed to stabilize the final product (solid wood panels). The beech wood samples used in this study were steamed for two different periods. PVAc and polyurethane (PU) adhesives were used to analyze bonding strength and durability. The bonding strength was measured according to the EN 13354 standard. The samples were treated before testing according to the first part of the standard, i.e., immersion in water. The durability of the bonded joint was tested according to the ISO 9142 standard. The samples were treated before testing with two methods. The results of the bonding strength show the influence of the steaming process on the bonded joint. Short exposure to steam decreased bonding strength, and prolonged exposure increased bonding strength. From the results given and the statistical analysis, it can be concluded that a prolonged steaming period increases the stability of the beech wood and thus the durability of the bonded joints.