Effect of pre-pressing of veneer on the glueability and properties of veneer-based products

Bekhta, Pavlo; Niemz, Peter; Sedliacik, J

doi:10.1007/s00107-010-0486-y

Cited by 58 publications

(36 citation statements)

References 12 publications

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“…Gaff and Gasparik (2015) studied densified beech veneers, and they noted that densification of veneers has important effects on their bending properties. Similar results were reported by Bekhta et al (2009) and Bekhta et al (2012). Glass fiber fabric also was used to reinforce poplar LVL.…”

Section: Mechanical Propertiessupporting

confidence: 81%

Some technological properties of laminated veneer lumber produced with fast-growing Poplar and Eucalyptus

Bal

2016

Maderas, Cienc. tecnol.

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Fast-growing tree species are important due to their short growth time before they are harvested. Both the Poplar and Eucalyptus species are fast-growing trees. These two species have been cultivated in many parts of the world, and they are used in several ways, including in the pulp and paper industry, as wood-based panels, and as structural composite lumber. In this study, laminated veneer lumbers were produced using different combinations of Poplar (Populus x euramericana I-214) and Eucalyptus (Eucalyptus grandis) veneers. Some physical and mechanical properties, including density, thickness swelling, water absorption, modulus of elasticity, modulus of rupture, impact bending, and bonding performance were investigated. According to the test data that were obtained, the mechanical properties of laminated veneer lumbers produced with Eucalyptus were greater than those of laminated veneer lumbers produced with Poplar. When the two were combined and Eucalyptus was used as the top and bottom plies, the mechanical properties also were better than those of Poplar laminated veneer lumbers. As a result, it can be said that both Poplar and Eucalyptus veneers can be used to produce laminated veneer lumbers, and Poplar laminated veneer lumbers can be reinforced with Eucalyptus veneers.

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Section: Mechanical Propertiessupporting

confidence: 81%

Some technological properties of laminated veneer lumber produced with fast-growing Poplar and Eucalyptus

Bal

2016

Maderas, Cienc. tecnol.

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“…smoother surfaces, is very important for various applica-tions of solid wood, in addition to reducing material loss in finishing machines. Similar results of surface quality improvement through thermal treatment were obtained in Betula pubescens (Bekhta et al 2012), P. nigra (Gündüz et al 2008), and E. camaldulensis (Unsal and Ayrilmis 2005) a T1: 1 step/25% final pressure; T2: 2/25%; T3: 1/50%; T4: 2/50%; *statistically significant difference compared to the control using the Dunnett test at α = 0.05…”

Section: Surface Roughnesssupporting

confidence: 70%

Properties of Thermo-Mechanically Treated Wood From Pinus Caribaea Var. Hondurensis

Santos¹,

Menezzi²,

Souza³

2012

BioResources

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This study aimed at evaluating the effect of thermo-mechanical treatment on properties of Pinus caribaea var. hondurensis wood. Two pressure levels (25% and 50% of the compression strength perpendicular to grain) were evaluated. The treatment was applied in a laboratory hot press in one-step or two-step modes for 50 minutes. In the one-step treatment, the total pressure was applied after the temperature of the center of the wood reached 170°C. In the two-steps treatment, half of the pressure was applied after the center of the wood reached 100°C, and the final pressure was applied when it reached 170°C. The weight loss immediately after treatment was equivalent to the wood moisture content, indicating that degradation of wood polymers did not occur. However, the treatments showed decreasing values of the moisture content, which were reduced from 12.3% to 9.8%. A moderate improvement on surface roughness was achieved, while wood wettability was highly reduced in all treatments, as determined by contact angle measurement. On the other hand, the treatment applied did not improve the wood dimensional stability, but all mechanical properties presented a trend of improvement.

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“…Arruda (2012) produced plywood with thermally treated laminates of amescla wood and obtained a CR ranging from 10.54% (at 140 °C) to 15.51% (at 180 °C). Bekhta et al (2012) observed a clear relationship between compression ratio and treatment parameters, such as temperature, pressure, and time. According Equal letters do not differ statistically from each other.…”

Section: Discussionmentioning

confidence: 90%

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

Costa

Menezzi

2017

Rev. Árvore

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-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 °C, 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 °C, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 °C.Keywords: Thermo modification; Wood panels; Densification EFEITO DO TRATAMENTO TERMO-MECÂNICO SOBRE AS PROPRIEDADES DE COMPENSADOS DE PARICÁ (Schizolobium amazonicum Huber ex Ducke)RESUMO -O tratamento termomecânico é uma metodologia para modificação da madeira, onde as amostras são densificadas por meio do calor e da compressão mecânica aplicada perpendicularmente às fibras, que submetidas a diversas combinações de tempo, temperatura e pressão aumentam a densidade da madeira e assim melhoram algumas de suas propriedades. O presente trabalho teve como objetivo tratar termomecanicamente compensados de paricá e observar os efeitos nas suas propriedades físicas e mecânicas. Os corpos-de-prova foram submetidos a dois tratamentos: a 120°C e a 150°C, mantidos sob pressão por sete minutos e, posteriormente, sob pressão zero, por quinze minutos. Os resultados mostraram que houve aumento significativo da massa específica de 0,48g/cm 3 para, em média, 0,56 g/cm 3 , e a taxa de compressão foi de 31,7% em média. As propriedades físicas também variaram significativamente, e os resultados mostraram que as amostras tratadas incharam e absorveram mais água que as testemunhas, levando a uma maior TNRE (taxa de não-retorno em espessura). Isto indica que os tratamentos térmicos propostos não liberaram as tensões internas de compressão geradas durante a prensagem do painel, não melhorando sua estabilidade dimensional. As propriedades mecânicas, por sua vez, foram afetadas positivamente, levando a um aumento de 27,5% e 51,8% do MOR após os tratamentos a 120°C e a 150°C, respectivamente. O MOE e o cisalhamento...

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Effect of pre-pressing of veneer on the glueability and properties of veneer-based products

Cited by 58 publications

References 12 publications

Some technological properties of laminated veneer lumber produced with fast-growing Poplar and Eucalyptus

Some technological properties of laminated veneer lumber produced with fast-growing Poplar and Eucalyptus

Properties of Thermo-Mechanically Treated Wood From Pinus Caribaea Var. Hondurensis

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

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