Glue Line Shear Strength Research Articles

FEASIBILITY OF USING Zanthoxylum ekmanii (Urb.) Alain FOR PLYWOOD PANEL PRODUCTION

Feasibility of using Zanthoxylum ekmanii (Urb.) Alain for plywood panel production.The demand for wood-based products by society is growing because these products are less restrictive, highly resistant, and reliable in use. However, due to a lack of technological knowledge, the number of Amazonian species used within the timber industries is still limited. Therefore, knowing the potential use of these species is important to the forestry sector’s development. In this context, this study aimed to evaluate the physical and mechanical properties of plywood panels produced with veneer sheets of Zanthoxylum ekmanii (lemon) and its combination with Pinus sp., using the urea-formaldehyde (UF) and (PF) phenol-formaldehyde resins. Panels were produced with 15 mm, dimensions of 50 x 50 cm, and a grammage of 360 g/m2 in a single line. Physical and mechanical tests were performed by the specifications described in the Brazilian standards. The results were compared to the requirements of the ABIMCI technical catalog and the NBR ISO 12466-2 standard. The homogeneous and combined panels with Z. ekmanii evaluated in this study presented results of water absorption, thickness swelling, compression set recovery, glue line shear strength, and parallel and perpendicular static bending statistically equal to or superior to the reference species (Pinus sp.). Therefore, the panels produced with Z. ekmanii have good quality in bonding with UF and PF resins. This species can be used in the production of homogeneous plywood or combination with Pinus sp.

Preparation and characterization of plywood panels using recycled HDPE as a formaldehyde-free adhesive: A comparative study

Formaldehyde-based resins such as urea-formaldehyde (UF) are the most widely used adhesives in the plywood industry. However, due to the concerns about formaldehyde toxicity, there is a need to develop formaldehyde-free adhesive materials. Therefore, the present study aimed to minimize or eliminate the harmful effects of UF resin by using recycled high-density polyethylene (HDPE) from post-consumed fruit packing boxes as a nontoxic adhesive. Three-layer plywood panels using poplar veneers and recycled HDPE films were prepared. UF was used as a control adhesive for the comparison. The influence of three variable parameters in terms of HDPE content (from 80 to 320 g/m2), hot-pressing temperature (from 140 to 180 °C), and pressing duration (from 3 to 8 min) on the properties of plywood panels were evaluated. For evaluation, physical properties, namely water absorption (WA), thickness swelling (TS), and mechanical properties, namely modulus of elasticity (MOE), modulus of rupture (MOR), and glue-line shear strength of the samples, were studied. The findings of this work confirmed that HDPE films gave the values of mechanical properties of plywood panels comparable to those obtained with UF adhesive, even though the adhesive content and pressing time were lower than when the UF adhesive was used. The obtained bonding strength values of HDPE-bonded plywood panels ranged from 0.82 to 1.60 MPa and met the requirement for the European Standard EN 314-2. According to FE-SEM micrographs, the fractured surface of plywood panels with 240 g/m2 of HDPE displayed a homogeneous cross-section area, and a large amount of HDPE was attached to the veneer surfaces. It was found that the average mechanical properties tended to increase with an increase in the pressing temperature and time. The type of adhesive had a significant effect on WA and TS. The smallest values of WA and TS were observed in plywood samples using high contents of HDPE films (240 and 320 g/m2). The optimum conditions were an HDPE loading of 240 g/m2, a hot-pressing temperature of 160 °C, and a hot-pressing time of 5 min. The overall results showed that recycled HDPE had enough potential to reuse as a promising adhesive for the environmentally-friendly plywood manufacturing.

EVALUATION OF THE PHYSICO-MECHANICAL PROPERTIES OF PLYWOOD PANELS AND LAMINATED VENEER LUMBER OF Pinus glabra Walt.

This work evaluated the potential of the species Pinus glabra for the production of laminated panels, as well as the effect of the density of the veneers and their combination on the quality of the product. The plywood and laminated veneer lumber were produced from two veneer density classes and the combination between them, namely: panels with veneers from 0.33 to 0.40 g/cm3; panels with veneers ranging from 0.41 to 0.48 g/cm3; and panels with veneers of 0.33-0.40 g/cm3 in the inner layer and 0.41-0.48 g/cm3 in the outer layer, resulting in 6 treatments. Phenol-formaldehyde was used as adhesive, whose formulation was 100 pbw of adhesive, 20 pbw of extender, 10 pbw of filler and 20 pbw of water, and applied at a grammage of 180 g/m². The pressing parameters were 1 MPa and temperature of 160ºC for 8 minutes. The evaluation of the quality of the panels was performed through tests of apparent specific gravity, static bending and glue line shear strength, according to European standards. The results presented that the production of panels, from the classification of veneers by densities and combination between them, provides gains in strength and stiffness. The parallel direction of the veneers (in LVL) provided gains in strength and stiffness when compared to panels produced with veneers perpendicular to each other (plywood), being, therefore, the most suitable for structural use. Finally, we have the conclusion that the species Pinus glabra has potential for producing laminated panels.

Physical and Mechanical Properties of Eco-Friendly Composites Made from Wood Dust and Recycled Polystyrene

The development of alternative wood composites based on the use of waste or recycled materials can be beneficial due to over exploitation of natural resources. Under this frame, an option for the successful utilization of waste polystyrene which avoids environmental problems that formaldehyde adhesives cause and also reduces waste disposal, is its potential application as a binder for the production of value-added environmentally friendly and low cost wood composites. Two types of panel were successfully made, consisting of wood dust and two recycled polystyrene contents, namely, 15% and 30%. Both physical properties, water absorption and thickness swelling, and mechanical properties, modulus of rupture, shear strength parallel in the plane of the board and glue line shear strength, were significantly improved as the recycled polystyrene content increased from 15% to 30%. Water absorption and thickness swelling after 24 h immersion in water were improved by 165% and 750% as the recycled polystyrene content increased from 15% to 30%. The magnitude of the improvement in mechanical properties however, was less pronounced than of the physical properties since modulus of rupture, shear strength parallel in the plane of the board and glue line shear strength were increased by 43.6%, 50% and 61.5%, respectively. The low viscosity of the recycled polystyrene caused more mobility inside the panel matrix and therefore, an improved penetration took place into adequate depth of the compressed dust particles. It is concluded that boards can be successfully produced using these waste raw materials, wood dust and recycled polystyrene in organic solvent as a binder, and therefore it can reduce waste disposal and provide cleaner production for the development of wood-based boards.

Nanocellulose-reinforced phenol-formaldehyde resin for plywood panel production

The search for new technologies to improve adhesives and the properties of reconstituted wood panels is constant, and nanotechnology is a tool for this purpose. The aim of this study is investigating the effect of adding nanocellulose in the formulation of the adhesive phenol-formaldehyde on the physico-mechanical properties of Pinus taeda plywood panels. Three ratios of nanofibrillated cellulose (NFC) were added to the adhesive formulation used to produce plywood panels: 0,026 %, 0,038 % or 0,064 %. The panels were tested according to the European standards; apparent density, resistance to parallel and perpendicular flexure and glue line shear strength were determined after 6 hours of boiling and after the boiling cycle for the 1st glue line (face) and 2nd line (core). The use of NFC in the adhesive caused an increase of viscosity and reduction of the gel time of the adhesive. The apparent density of the panels was not influenced by the addition of NFC, but the properties of parallel bending, perpendicular flexing and glue line shear were sensitive to the addition of NFC. The NR2 treatment (0,038 % NFC) presented the best results in the mechanical tests

PRODUCTION OF PLYWOOD WITH VENNERS OF Maquira coriacea (Karsten) C.C. Berg

In the present study, the quality of plywood made with veneers of Maquira coriacea (Karsten) C.C. Berg, was evaluated. Plywoods of five 60 cm x 60 cm veneers, glued with urea formaldehyde resin with 65% solids, were made using adhesive formulations A (Resin:100, Extender: 20, Catalyst:1.5, Water:20), B (Resin:100, Extender:40, Catalyst:1.7, Water:40) and C (Resin:100, Extender:60, Catalyst:1.9, Water:60) and grammages of 220 g/m 2 and 260 g/m 2 . Panels were pressed at specific pressure of 10 kgf/cm 2 , temperature at 120 °C and pressing time of 10 minutes. MOR and MOE in static bending were evaluated in the parallel and perpendicular to the grain as well as the glue line shear strength. Plywood made with formulation A and 260 g/m 2 grammage shows greater resistance to static bending parallel, with a 43.51 MPa MOR and 4576 MPa MOE, and perpendicular to the grain with a 21.88 MPa MOR and 2129 MPa MOE, as well as the glue line shearing strength (dry: 2.42 MPa and wet: 1.90 MPa). Likewise, the formulation positively influences the MOR and MOE perpendicular and parallel to the grain, while the grammage only in the perpendicular. Shear strength in the glue line meets the requirements of the correspondent standard, finding that the interaction between the amount of glue used and the formulation is not significant. It is concluded that the plywood of Maquira coriacea shows satisfactory resistance properties for indoor use, being recommendable to use, to reduce costs, the formulation C and a grammage of 220 g/m 2 .

Combining Thermo-Hydro-Mechanical and Phenol-Resin Impregnation Treatments: Potential for High-Density Poplar Flooring

Abstract Thermo-hydro-mechanical (THM) treatments can be used to improve certain properties of underutilized wood species, especially those with low densities. These treatments densify the wood by softening the cell walls using heat, pressure, and moisture but are subject to set-recovery (recovery of compressive deformation) when exposed to humidity. Phenol-based resins have been successful in mitigating this issue when impregnated into the wood. This work explores the use of a new phenol-based resin combined with a THM treatment to limit set-recovery and produce products with the potential for flooring applications. Scratch resistance, hardness, and glue-line shear strength were used to assess the performance. The THM treatment and impregnated phenol resin used in this study increased the scratch resistance, density, and hardness of natural poplar wood and created satisfactory bonding conditions for flooring purposes. With optimization of THM parameters and resin solids content, the resulting product could provide a high-quality flooring material used alone or as a thin laminate from a low-density species like poplar.

Production of Joints Of Eucalyptus Sp. to Obtain Edge Glued Panels

ABSTRACT This research aimed at evaluating the quality of bonded joints of Eucalyptus wood by using different faces and adhesives to produce EGP (Edge Glued Panels). Glue line shear specimens were obtained from bonded joints glued with PVAc (Polyvinyl Acetate) and EPI (Emulsion Polymer Isocyanate) adhesives, using pieces oriented with tangential, radial and intermediary faces, as well as the combination between them. The specimens were submitted to two pretreatments in order to simulate the use of joints in dry and wet environments. For shear tests, 12 treatments were obtained. The results indicated that the use of tangential x tangential and tangential x intermediary bonding faces and EPI adhesive presented better glue line shear strength for EGP in dry and wet pretreatments, respectively. The joints bonded in the radial x radial direction presented statistically inferior values when compared to the other treatments.

Bonding performance of melamine-urea–formaldehyde and phenol-resorcinol–formaldehyde adhesive glulams at elevated temperatures

To better understand the bonding performance of glued laminated timbers (i.e., glulams) during fires, phenol–resorcinol–formaldehyde (PRF) and melamine–urea–formaldehyde (MUF) adhesives were used to investigate the effects of elevated temperatures on the glueline shear strength. The wood failure mode was observed to study the heat resistance of the two adhesives. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to analyze chemical and microscopic changes at various temperatures. The parallel-to-grain shear strength of solid larch wood decreased linearly with increasing temperature. Bonding strength of the wood–PRF glueline exposed to elevated temperatures was similar to that of the solid wood. The wood–MUF glueline exhibited good bonding performance at room temperature but showed poor thermal resistance. Shear strength of wood–MUF glueline was 0 MPa at 280 °C. Bonding performances of PRF and MUF deteriorated linearly with increasing temperature. FTIR analysis showed that PRF could maintain a relatively intact chemical structure when the temperature was higher than 150 °C, and the structure of the MUF degraded significantly when the temperature was higher than 200 °C.

THE USE OF Eucalyptus camaldulensis AND Eucalyptus urophylla WOOD IN THE PRODUCTION OF EDGE GLUED PANELS

This study aimed to evaluate the shear strength of bonded wood joints of Eucalyptus camaldulensis and Eucalyptus urophylla with vinyl polyacetate (PVA) and isocianate polymeric emulsion (EPI) adhesives with the amount of glue of 150 and 180 g/m². The specimens were submitted to shear tests in dry and wet conditions, based on the procedure described in standard EN 13354 (2008). The results of the 5th lower percentile were compared with the requirements of EN 13353 (2008). Among the studied species, Eucalyptus camaldulensis showed better glue line shear strength when compared to Eucalyptus urophylla. However, both species are potentially viable for the edge glued panel (EGP) production, since they meet the minimum requirement of 2.5 MPa, referring to the 5th lower percentile, as established by EN 13353-2008 standard. Based on the results, it is recommended the use of EPI adhesive with the amount of glue of 150 g/m² for the bonding of the wood of these species, aiming at the production of EGP.

The glueline shear strength of Peronema canescens and Acacia hybrid

The glueline shear strength is one of the common measures used to estimate potential performance of bonded wood joints. This study was conducted to determine the glueline shear strength of Pernonema canescens (Sungkai) and Acacia hybrid (A. hybrid). The wood were bonded with polyvinyl acetate (PVAc) and Emulsion Polymer Isocyanate (EPI) and these are for dry use in non-structural timber production. Sungkai and A. hybrid logs were obtained from Telipok and Ulu Kukut, Sabah respectively, were debarked, sawn and air-dried prior to being sawn to 20 mm thick, 60 mm wide and 150 mm long. After reaching the constant moisture content, the gluing process was carried out. 2 types of adhesives were used; EPI and PVAc. The glue was spreaded at a constant spreading rate of 200 g/m2. 3 types of assembly combinations were made; Sungkai-Sungkai, A. hybrid-A. hybrid and Sungkai-A. hybrid. The assemblies were clamped for 24 hours, as recommended by the glue manufacturer. The test specimen preparation and the glueline shear strength test was conducted in accordance with the Manual for Testing Methods for Plantation Grown Tropical Timbers (Finger and Laminate Joints in Non-Structural Timber Production). The results showed that, the average glueline shear strength of Sungkai-Sungkai, A. hybrid-A. hybrid. and Sungkai-A. hybrid bonded with EPI are 7.48 N/mm2, 6.58 N/mm2, 6.87 N/mm2 respectively. While the average glueline shear strength of Sungkai-Sungkai, A. hybrid-A. hybrid and Sungkai-A. hybrid bonded with PVAC are 7.61 N/mm2, 6.03 N/mm2, 7.60 N/mm2 respectively. Based on the results obtained, the glueline shear strength for all assembly combinations exceed the minimum requirement of the shear strength for laminate joints, which is 5.32 N/mm2. Thus, Sungkai and A. hybrid wood have the potential to serve as supplemental raw material for the non-structural timber production.

Bonding strength test method assessment for Cross-Laminated Timber Derived Stressed-Skin Panels (CLT SSP)

Different methods, including bending tests and small and medium size shear tests, were used to assess the skin to stringer glue line shear strength of Radiata Pine Cross-Laminated Timber Derived Stressed-Skin Panels (CLT SSP). Bending test shear strengths were estimated using the mechanically jointed beam theory (gamma method) for Cross-Laminated Timber (CLT) panels with modifications in the layers’ effective widths, and then compared with results from the small and medium size shear tests. Small and medium size shear tests proved to be possible methods for assessing bonding strength for factory production control. The small shear tests provided lower strength values and higher scatter results than those gathered from the medium size tests. The mean shear strength results obtained from bending tests were inferior to the values obtained from the small and medium size specimens. The bending tests proved necessary for assessing the mechanical behaviour of CLT SSP.

Evaluation of glue line shear strength of laminated timber structures using block and core type specimens

Monitoring and evaluation of glued laminated timber structures in service is essential to warrant its integrity, where non-destructive techniques play an important role. This paper describes the results obtained on glued laminated timber beams of maritime pine, with and without preservative treatment, and of spruce, exposed to natural outdoor environment as well as to artificial weathering. The assessment of glue lines’ shear strength was investigated through the extraction and testing of cores parallel and perpendicular to the glued lines and block shear specimens with 50 mm × 50 mm and 20 mm × 20 mm shear area. The results highlight the different performances of the various types of specimens tested, showing that the measured shear strength depends on the specimen size and that the size effect depends on the material strength giving a decreasing modification factor with the increase of strength in opposition to the constant factor suggested by standard EN 14080. They also show that shear testing of cores drilled perpendicular to the glued joints may be a promising tool in the assessment of glulam structures on site.

EFFECT OF THERMO-MECHANICAL TREATMENT ON PROPERTIES OF PARICA PLYWOODS (Schizolobium amazonicum Huber ex Ducke)

ABSTRACT Thermo-mechanical treatment is a technique for wood modification in which samples are densified by means of heat and mechanical compression, applied perpendicularly to fibers, which under different combinations of time, temperature, and pressure increases wood density and thus improve some of its properties. This study aimed to treat thermo-mechanically parica plywood and observe the effects on its physical and mechanical properties. Specimens were submitted to two treatments, 120 and 150 ºC, remaining under pressure for seven minutes and, subsequently, under zero pressure for 15 minutes. Results showed a significant increase in specific mass from 0.48 g cm-3 to an average of 0.56 g cm-3, and a compression ratio of about 31.7% on average. Physical properties also varied significantly and results showed that treated samples swelled and absorbed more water than those untreated, leading to a greater thickness non-return rate. This indicates the proposed thermal treatments did not release the internal compressive stress generated during panel pressing, not improving its dimensional stability as a result. On the other hand, mechanical properties were positively affected, leading to an increase of 27.5% and 51.8% in modulus of rupture after treatments at 120 and 150 ºC, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 ºC.

KAYIN VE KAVAK KAPLAMALARIN MELAMİN FORMALDEHİT TUTKALI KULLANILARAK LAMİNE KAPLAMA KERESTE ÜRETİMİNE UYGUNLUĞU

Laminated Veneer Lumber (LVL) has been proven their usefulness and efficiency as framing members (girders, beams, joist, headers, panels, etc.)in construction. Their application and manufacture is limited in Turkey. In this study, four different types of 7-layers LVLs were successfully manufactured using sawed beech (B) and poplar (P) veneers, and melamine formaldehyde (MF) adhesive. In this work, LVLs were formed with two veneers for each surface and three veneers for core layer. Produced four different types of LVL were coded based on the type and location of the veneers. BBBBBBB, BBPPPBB, PPPPPPP and PPBBBPP were called as Group I, Group II, Group III and Group IV, respectively. As physical properties, oven dry specific gravity (SG) and moisture content (MC) were determined according to TS 2472 (1976a) and TS 2471 (1976b) standards. Mechanical properties like glueline shear strength, modulus of rupture (MOR), modulus of elasticity (MOE) and compression strength (CS)(parallel to grain) were also determined according to EN 314-1 (2004),EN310 (1993) and TS 2595 (Anonymous 1977)standards, respectively. Based on this study, the highest strength and SG values were obtained with all beech used veneers (Group I). On the other hand lowest values were recorded with all poplar veneers (Group III). It should be noted that contribution rate of beech veneers in LVL had an increase on both strength and SG values.

Properties of a Laminated Wood Composite Produced with Thermomechanically Treated Veneers

The paper aimed at evaluating the properties of plywood made from thermomechanically treated wood veneers. Veneers from Amescla (Trattinnickia burseraefolia) wood were treated in a hydraulic press with electric resistance heating. Two temperature levels were applied, 140°C and 180°C, for 1 and 2 minutes with 2.7 N/mm2of pressure. A total of 30 plywood boards were produced, including six boards produced from untreated veneers. The results showed that the thermomechanical treatment did not have any deleterious effect on glue line strength and most of the mechanical properties of plywood made from treated veneers were improved. On the other hand, plywood made from untreated veneers presented better dimensional stability. Dimensional stability properties were most affected by the temperature of the treatment, while mechanical stability, represented by the glue line shear strength, was positively affected by temperature and duration of the treatment.

PROPRIEDADES FÍSICO-MECÂNICAS DE PAINÉIS DE LÂMINAS PARALELAS REFORÇADOS COM PRFV

http://dx.doi.org/10.5902/1980509819676O objetivo desta pesquisa foi avaliar as propriedades físico-mecânicas de painéis de lâminas paralelas (LVL) com camadas de Polímeros Reforçados de Fibra de Vidro (PRFV) impregnadas com dois tipos de matrizes. Primeiramente foi realizada a fabricação dos painéis LVL com nove camadas de lâminas de madeira unidas com resina à base de fenol-formaldeído na gramatura de 190 g/m2 em linha simples. Posteriormente, foi feita a aplicação do reforço de fibra de vidro impregnado com resinas epóxi ou poliéster isoftálica com NPG. Os tratamentos consistiram na aplicação de uma a quatro camadas de fibra de vidro impregnadas com resina epóxi ou isoftálica, totalizando 21 painéis. As propriedades avaliadas foram a massa específica, o teor de umidade, a flexão estática na posição flatwise e egdewise e a resistência ao cisalhamento na linha de cola. Em flexão estática na posição flatwise, uma camada de PRFV, em tratamentos com resina epóxi e isoftálica, foi suficiente para influenciar o módulo de elasticidade (MOE), enquanto para o módulo de ruptura (MOR), duas camadas de PRFV foram necessárias para tratamentos com resina isoftálica e uma camada para tratamentos com resina epóxi. Na posição edgewise, os valores de MOE e do MOR se mantiveram estáveis após a aplicação de duas camadas de PRFV. A resina epóxi apresentou maior resistência ao cisalhamento e maior percentual de falhas na madeira, enquanto a resina isoftálica, apesar de apresentar valores de resistência similares à fenólica, não apresentou boa adesão à madeira, representada pelo baixo percentual de falhas na madeira. Portanto, a aplicação de uma camada de PRFV com resina epóxi na posição de tração seria o suficiente para melhorar as qualidades mecânicas (flexão estática e cisalhamento) dos painéis LVL fabricados com lâminas de madeira de pinus unidas com fenol-formaldeído.

Investigation of Glueline Shear Strength of Pine Wood Bonded with PVAc by Response Surface Methodology

The effects of process parameters (adhesive spread, press time, and applied pressure) on the response parameter (shear strength) of pine wood bonded with PVAc were studied. Response surface methodology was applied for design of experiments and for analysis of results. A mathematical model was developed to establish the relationship between the process parameters and response parameters. The results showed that the major factors were adhesive spread and applied pressure. The shear strength increased as the adhesive spread and applied pressure increased within certain ranges.

EFFECT OF WOOD GRADING ON THE MECHANICAL PROPERTIES OF GLULAM MADE OF Tectona grandis

AbstractThis study aimed to evaluate the influence of the wood grading by the method of stress waves in the mechanical properties of glued laminated beams (glulam) made of Tectona grandis. A total of 87 battens with dimensions of 25 x 75 x 3.000 mm were obtained from the 5 trees and 3 logs per tree, in the axial direction (base, middle and top) and radial (pith - bark). After drying, the battens were planed to the final dimensions of 20 x 60 x 2200 mm, and then subjected to grading by application of stress waves. Were defined three classes of dynamic modulus of elasticity (DMOE) and the beams were composed with five pre-classified battens. The beams were bonded with resorcinol-phenol-formaldehyde resin, with a weight of 350 g / m² (double surface), specific pressure of 1.0 MPa and pressing time of 8 hours. The grading process of the battens using the stress wave method showed to be efficient for the composition of beams. The results of static bend and glue line shear strength tests indicated the technical feasibility of using wood of Tectona grandis for the production of glued laminated beams.Keywords: Wood bonding; structural wood; resorcinol-phenol-formaldehyde resin. ResumoInfluência da classificação das lamelas nas propriedades mecânicas de vigas laminadas coladas de Tectona grandis. Este trabalho teve como objetivo avaliar a influência da classificação da madeira pelo método de ondas de tensão nas propriedades mecânicas de vigas laminadas coladas de Tectona grandis. Um total de 87 lamelas com dimensões de 25 x 75 x 3.000 mm foram obtidas a partir da amostragem de 5 árvores e 3 toras / árvore, nas direções axial (base, meio e topo) e radial (medula – casca). Após a secagem, as lamelas foram aplainadas para as dimensões finais de 20 x 60 x 2.200 mm, sendo a seguir submetidas à classificação por meio de aplicação de ondas de tensão. Foram estabelecidas três classes de módulo de elasticidade dinâmico (MOEd) e as vigas foram compostas de cinco lamelas pré-classificadas. As vigas foram coladas com resina resorcina-fenol-formaldeído, com gramatura de 350 g/m² (linha dupla), pressão específica de 1,0 MPa e tempo de prensagem de 8 horas. A classificação das lamelas pelo método de ondas de tensão mostrou ser eficiente para a composição das vigas. Os resultados de ensaios de flexão estática e cisalhamento da linha de cola indicaram a viabilidade técnica de uso da madeira de Tectona grandis para produção de vigas laminadas coladas.Palavras-chave: Colagem de madeiras; estruturas de madeira; resina resorcina-fenol-formaldeído.

QUALITY OF PLYWOODS OBTAINED FROM Melia azedarach COMBINED WITH Pinus taeda, PRODUCED WITH UREA-FORMALDEHYDE AND PHENOL-FORMALDEHYDE RESINS

AbstractThis study was developed to evaluate the quality of plywood produced from Melia azedarach in combination with Pinus taeda, glued with urea-formaldehyde resin (UF) and phenol formaldehyde (PF). Panels were produced using five veneers of Melia azedarach only, five veneers of Pinus taeda and also with faces made of Melia azedarach and core with Pinus taeda. The panels were evaluated by glue line shear tests and by static bending in parallel and perpendicular directions. The higher contents of extractives in Melia azedarach wood did not reduce the glue line shear strength between the layers. For both UF and PF glues, panels produced with veneers of Melia azedarach showed better results on static bending and glue line shear tests. The results indicate great potential of Melia azedarach wood in plywood production, both for internal use (UF), and for external use (PF).Keywords: Cinamomo; wood veneer; glue line. ResumoQualidade de painéis compensados de Melia azedarach em combinação com Pinus taeda produzidos com resina uréia-formaldeído e fenol-formaldeído. O objetivo deste trabalho foi avaliar a qualidade de painéis compensados de Melia azedarach em combinação com Pinus taeda, produzidos com resina ureia-formaldeído (UF) e fenol-formaldeído (FF). Foram produzidos painéis com todas as cinco lâminas de Melia azedarach e de Pinus taeda, e capas de Melia azedarach e miolo de Pinus taeda. Os painéis foram avaliados por meio de ensaios de cisalhamento da linha de cola e flexão estática paralela e perpendicular. Maiores teores de extrativos presentes na madeira de Melia azedarach não prejudicaram a resistência da linha de cola entre as lâminas. Tanto para a colagem uréica, quanto para a fenólica, os painéis produzidos com lâminas de Melia azedarach apresentaram melhores resultados nos ensaios de flexão estática e de cisalhamento da linha de cola. Os resultados obtidos indicam grande potencial da madeira de Melia azedarach para produção de painéis compensados, tanto para uso interior (UF), quanto para uso exterior (FF).Palavras-chave: Cinamomo; lâminas de madeira; linha de cola.