Mechanical Properties Of Plywood Research Articles

Experimental design to determine the manufacturing parameters of a green-glued plywood panel

The objective of this research was to investigate the technical feasibility of producing plywood by green-gluing technology. 2.5 mm thick rotary cut veneers obtained from steamed maritime pine (Pinus pinaster Ait.) logs were used. Plywood was manufactured under vacuum with veneers in a wet state. Five-layer plywood panels were produced using a one-component polyurethane adhesive to evaluate the effects of two parameters, the wood moisture content and the amount of adhesive, on the mechanical properties of plywood. First, a full factorial experimental design was realised to study the bond performance. Shear tests were carried out in order to determine the bond quality and failure type. It was observed that the values of plywood panels’ shear strength depend more on the wood moisture content than on the amount of adhesive applied. A model representing the shear strength of the panels according to the manufacturing parameters was established by using statistical analyses. Another part of this study focused on microscopic observations of the bondline in order to get information about the joint morphology and the degree of adhesive penetration into the wood structure. Results suggested that definite proportions of water (moisture content between 30 and 60 %) and adhesive have to be present on wood surface when gluing to create efficient bonds. These analyses were followed by the panel’s characterisation in flexure to validate the process.

Mechanical Properties of 3 Ply Plywood Made fromAcacia MangiumVeneers and Green Starch-based Adhesives

Recently, starch has attracted great consideration as a raw material on wood adhesives in the wood industry. Cassava and sago starchbased adhesive are renewable, biodegradable and environmental friendly product when compared with other petroleum-based adhesives. In this study, different starches-based adhesive has been produced. Mechanical properties of plywood made from Acacia mangium veneers with different starches-based adhesives (cassava and sago) as binder cured at different curing temperatures (100°C, 120°C and 140°C) has been determined. All materials (starch, vinegar, water and glycerol) were cooked and stirred until the mixture reached 70°C - 80°C which become sticky and whitish. After that, starch-based adhesives were applied on the veneers by using spreader, and the plywood were pre-pressed for 30 minutes with 20 kg load before hot-press. Cassava starch-based adhesive showed the highest Modulus of Elasticity which was 12410.56 N/mm 2 than sago starch-based adhesive, while Modulus of Rupture of the cassava starch-based adhesive at 100°C showed highest mean value at 74.19 N/mm 2 . Sago-starch based adhesive at 140°C showed the highest shear strength with 1.11 N/mm 2 . In short, cassava and sago starch-based adhesives gave good performance in mechanical properties such as bending for pressed temperature (100°C and 120°C), and shear at 140°C pressed temperature.

Исследование физико-механических свойств фанеры с использованием клеев, модифицированных органическими наполнителями

Исследование физико-механических свойств фанеры с использованием клеев, модифицированных органическими наполнителями

Produção de painéis compensados estruturais com diferentes composições de lâminas de Eucalyptus saligna e Pinus caribaea

Este trabalho teve como objetivo avaliar a qualidade de painéis compensados estruturais produzidos com lâminas de Eucalyptus saligna e Pinus caribaea var. caribaea, var. hondurensis e var. bahamensis com diferentes composições de lâminas. Foram produzidos painéis experimentais com dimensões de 50 x 50 cm, utilizando-se cinco lâminas de 2,2 mm, com as seguintes composições: (1) painéis com todas as lâminas de mesma espécie/variedades (T1, T2, T3 e T4); e (2) painéis com lâminas de Eucalyptus saligna de forma intercalada com as lâminas de três variedades de Pinus caribaea (T5 a T10). Os painéis produzidos exclusivamente com lâminas de Eucalyptus saligna apresentaram valores superiores de resistência da linha de cola aos esforços de cisalhamento, MOE e MOR paralelo e perpendicular. A composição dos painéis com lâminas das duas espécies/variedades de forma intercalada não influenciou, de forma significativa, a resistência da linha de cola e MOE e MOR perpendicular. A disposição das lâminas de Eucalyptus saligna na capa dos compensados resultou em maiores valores de MOE e MOR paralelo. Os resultados das propriedades mecânicas avaliadas foram satisfatórios, em comparação com os valores de referência apresentados na literatura e com aqueles requisitos mínimos requeridos pela norma técnica, indicando a viabilidade de produção de painéis compensados do tipo "combi" com combinação de espécies de folhosas e coníferas.

Effect of Melamine Content in MUF Resin on the Durable Properties of Plywood

The effect of melamine content in melamine modified urea formaldehyde (MUF) resin on durable properties of plywood was investigated using ammonium chloride (NH4Cl) with different melamine/urea (M/U) ratios. The plywood specimens were exposed to laboratory accelerated aging and/or cyclic soak-dry (SD). The experiment results indicated that the melamine contents in MUF resin showed an unobservable effect on the durable properties of MUF resin bonded plywood. The mechanical properties of plywood decreased more severely after accelerated aging test in acidic condition. However, the influence of different curing catalyst contents on mechanical properties and formaldehyde emission of UF resin can be minimized by adding melamine to the resin.

Influence of acrylamide copolymerization of urea–formaldehyde resin adhesives to their chemical structure and performance

AbstractTo lower the formaldehyde emission of wood‐based composite panels bonded with urea–formaldehyde (UF) resin adhesive, this study investigated the influence of acrylamide copolymerization of UF resin adhesives to their chemical structure and performance such as formaldehyde emission, adhesion strength, and mechanical properties of plywood. The acrylamide‐copolymerized UF resin adhesives dramatically reduced the formaldehyde emission of plywood. The 13C‐NMR spectra indicated that the acrylamide has been copolymerized by reacting with either methylene glycol remained or methylol group of UF resin, which subsequently contributed in lowering the formaldehyde emission. In addition, an optimum level for the acrylamide for the copolymerization of UF resin adhesives was determined as 1%, when the formaldehyde emission and adhesion strength of plywood were taken into consideration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of moisture and fungal exposure on the mechanical properties of hem-fir plywood

Hem-fir plywood were exposed to two brown rot fungi,Gloeophyllum trabeum andPostia placenta, and one white rot fungus,Trametes versicolor, to investigate the effect of fungal decay on mechanical properties of plywood. Results showed that modulus of rupture (MOR) and modulus of elasticity (MOE) of hem-fir plywood declined significantly by inoculating fungi, and weight loss of sample had a modest decrease. The fungi also made a greater effect on MOR than on MOE. Of three fungi,Postia placenta caused a most significant weight loss, andGloeophyllum trabeum resulted in a largest flexural properties loss. Substantial declines in MOR and MOE of hem-fir plywood were also observed when the plywood samples were stored under wet conditions over 15 weeks, even in, the absence of fungal attack.

Effects of moisture content on formaldehyde emission and mechanical properties of plywood

Wood is a hygroscopic material and has ability to exchange its moisture content with air. Many mechanical properties are affected by changes in moisture content below the fiber saturation point of wood. This study evaluates the formaldehyde emission and some mechanical properties of poplar and spruce plywood panels manufactured from rotary cut veneers having different moisture content by using urea–formaldehyde (UF) and modified urea formaldehyde by melamine (M+UF). Rotary cut veneers obtained from poplar and spruce logs were classified into three groups and veneers in each group were then conditioned in a climate chamber to either 4–6%, 10–12% or 16–18% moisture content. Plywood panels with three plies and in 6 mm thickness were manufactured for each group. Formaldehyde emission, shear strength, bending strength and modulus of elasticity values of plywood panels were determined. Best bonding results were obtained in plywood panels with veneers having 4–6% moisture content. Lowest mechanical properties were found for plywood panels manufactured from veneers conditioned to 16–18% moisture content. Formaldehyde emission values of poplar and spruce plywood panels decreased with increasing veneer moisture content for both glue types. Formaldehyde emission content of panels decreased with melamine addition into the urea formaldehyde glue mixture.

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Th e r es u l t of t h e s u itability s tu dy of two wood s p e ci es a s ra w materia l for venee r and plywood ar e r epo r ted. The wood raw material u sed ru bber wood (Hevea brasiliensis) and sengon (Paraserianthes falcataria). The wood u sed were obtained from diffe r ent age classes i.e.10 and 20 years for ru bber wood and 10 a n d 1 5 years for sengon. The study co n sisted of log pee l i n g characteris t ic, veneer pr ope r ties and some p h ysica l -mecha n ical properties of plywood (triplex and multiplex). All of t h e logs from t wo wood species could b e peeled in cold condition, producing 1,5 mm ve n ee r at a cutting angle between 89 o 30'-9 1 o 30'. The average shrinkage of veneer is 4 .51 % and the average v eneer swel l ing fro m oven-dry to ai r dry is 3. 30 %. The bond i ng strengt h of plywood from all wood species conform with the I ndonesian standard, German standar d and Japanese standa r d fo r type 11 or water resistant. The spesific gravity and mechanical properties of plywood from the older tree tends higher t h an t hat from t he yo u nger t ree.

合板および集成材の力学的性質

合板および集成材の力学的性質