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Personne :
Cloutier, Alain

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Cloutier

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Alain

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Université Laval. Département des sciences du bois et de la forêt

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ncf10407795

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Voici les éléments 1 - 10 sur 11
  • PublicationRestreint
    An investigation of thermochemical changes in Canadian hardwood species during wood welding
    (Springer, 2013-02-09) Erakovic, Sanja; Cloutier, Alain; Stevanovic-Janezic, Tatjana; Diouf, Papa Niokhor; Prado, Maria; Pizzi, Antonio; Royer, Mariana; Belleville, Benoît
    Thermochemical changes during wood-dowel welding were investigated in two Canadian hardwood species commonly used for indoor appearance applications: sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis). The original reference wood sample and the welded interface between two bonded wood pieces, a dowel and a substrate, were compared to explain differences in mechanical properties between species. Pyrolysis gas chromatography–mass spectrometry (Py-GC/MS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS) were used. The gases emitted during wood welding were determined by Py-GC/MS and gas chromatography coupled with a thermal conductivity detector and a flame ionization detector (GC-TCD/FID). Results showed that thermal welding of birch and maple woods degrades hemicelluloses and affects lignin polymer through depolymerisation. Welding effectiveness is therefore directly associated with the properties of the original wood constituents, primarily lignin and carbohydrates. The lignin-related changes at the welded interface were greater for sugar maple than for yellow birch, corroborating mechanical property differences observed between the two species. The gases proportions were similar for both species and no harmful gases were detected in the smoke released during welding process.
  • PublicationAccès libre
    Heat and mass transfer properties of sugar maple wood treated by the thermo-hygro-mechanical densification process
    (MDPI, 2018-07-24) Fu, Qilan; Laghdir, Aziz; Cloutier, Alain
    This study investigated the evolution of the density, gas permeability, and thermal conductivity of sugar maple wood during the thermo-hygro-mechanical densification process. The results suggested that the oven-dry average density of densified samples was significantly higher than that of the control samples. However, the oven-dry density did not show a linear increase with the decrease of wood samples thickness. The radial intrinsic gas permeability of the control samples was 5 to 40 times higher than that of densified samples, which indicated that the void volume of wood was reduced notably after the densification process. The thermal conductivity increased by 0.5–1.5 percent for an increase of one percent moisture content for densified samples. The thermal conductivity of densified wood was lower than that of the control samples. The densification time had significant effects on the oven-dry density and gas permeability. Both densification time and moisture content had significant effects on thermal conductivity but their interaction effect was not significant.
  • PublicationRestreint
    Moisture content–water potential relationship of sugar maple and white spruce wood from green to dry conditions
    (Society of Wood Science and Technology, 1999-01-31) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    The moisture content-water potential relationship was determined at 40°C and 60°C for sugar maple (Acer saccharum Marsh.) sapwood and at 60°C for white spruce (Picea glauca (Moench.) Voss.) heartwood from green to dry conditions. The pressure membrane technique was used for high moisture contents and equilibration over salt solutions for low moisture contents. The results show that at high moisture contents, the equilibrium moisture contents obtained from the green condition are lower than those obtained from full saturation (boundary desorption). It is recommended that the sorption history must be taken into account when modeling wood drying. Water potential at a given moisture content increases with temperature. There is a characteristic plateau in the green moisture content-water potential relationship obtained for sugar maple at water potentials between -2,000 and -6,000 J kg-1, which can be attributed to its heterogeneous capillary structure. The maximum concentration of effective pore radius occurs at 0.02 μm in the case of sugar maple, corresponding to the size of the pit membrane openings.
  • PublicationRestreint
    Mechanical behaviour of sugar maple in cantilever bending under constant and variable relative humidity conditions
    (Wood Technology Society, 2013-11-18) Laghdir, Aziz; Cloutier, Alain; Segovia Abanto, Franz; Blanchet, Pierre
    The mechanical behaviour of wood over time depends on temperature, relative humidity, applied load and the direction of the applied load, among other factors. In the present study, the mechanical behaviour of sugar maple (Acer saccharum Marsh.) wood was determined using creep tests in cantilever bending. These tests were carried out at different load levels, in a controlled environment chamber at a constant temperature of 30± 0·5°C and a relative humidity of 37, 67 and 83% for constant conditions and a relative humidity ranging from 37 to 83% for variable conditions. The specimens were oriented in a radial pattern and cut to 110 mm in length, 25 mm in width and 7 mm in thickness. The results show the impact of load levels and moisture content. Under constant conditions, the results show a linear behaviour of viscoelastic creep. Under variable relative humidity conditions, changing moisture contents resulted in significantly higher creep (mechanosorptive) compared to constant conditions.
  • PublicationRestreint
    Production and properties of wood-welded panels made from two Canadian hardwoods
    (International Academy of Wood Science, 2013-05-18) Cloutier, Alain; Salenikovich, Alexander; Blanchet, Pierre; Stevanovic-Janezic, Tatjana
    This study examines the suitability of wood welding technology for producing composite panels for furniture applications with two Canadian hardwood species, sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis). For each species, twelve 30 9 225 9 300 mm3 panels were manufactured using a panelling machine specifically designed for rotational wood-dowel welding with optimized parameters obtained from a previous study. Six edge-glued panels of the same size were manufactured from each species using a non-structural polyvinyl acetate adhesive and tested for comparative purposes. The experimental programme included three-point bending at 255-mm span and visual inspection of the panels to assess performance at standard moisture conditions and after an ageing cycle with variable relative humidity. Average breaking load of 1.79 and 1.70 kN was obtained at standard moisture conditions for welded panels of yellow birch and sugar maple, respectively. Fractures consistently occurred in the dowel’s cross section, whereas no slippage was observed along the welded interface. Delamination between wood slats occurred after the ageing cycle, but did not affect the bending properties. Results confirm the suitability of wood-dowel welding for producing furniture panelling with Canadian hardwood species. Further research is needed to design panels with a more efficient position and use of welded dowels and with panel product properties that are comparable or superior to those of glued counterparts.
  • PublicationRestreint
    Determination of optimal wood-dowel welding parameters for two North American hardwood species
    (VSP, 2012-08-10) Cloutier, Alain; Stevanovic-Janezic, Tatjana; Pizzi, Antonio; Belleville, Benoît; Blanchet, Pierre
    Rotational wood-dowel welding has been shown to rapidly produce wood joints of considerable strength without any adhesive. The technique offers an opportunity to increase productivity and reduce costs in the furniture industry. The objective of the study was to define optimal wood-dowel welding parameters for two North American hardwood species frequently used for indoor appearance products: sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis). Optimized parameters for individually studied species were determined using a rotational wood-dowel welding machine designed for the technique. A comparative analysis of wood-dowel welding parameters was performed. The investigated parameters for both species were grain orientation, rotational speed, and insertion speed. Temperature profile measurements at the interface during rotational wood-dowel welding were also carried out. Optimal welding mechanical properties were determined from the dowel withdrawal strength using a standard tensile strength test. Results revealed a significant interaction between species, rotational speed, and insertion speed. Sugar maple produced wood joints with higher withdrawal strength than yellow birch. The best results for sugar maple and yellow birch were obtained with a rotational speed of 1000 rpm. A 25 mm s−1 insertion speed produced significantly stronger welded joints in sugar maple than at 12.5 mm s−1. For yellow birch, a 16.7 mm s−1 insertion speed provided the best results. Both species and rotational speed had a significant effect on peak temperature at the interface during welding. Peak welding temperatures with optimal parameters were 244 and 282 °C for sugar maple and yellow birch, respectively.
  • PublicationRestreint
    Determination of the effective water conductivity of sugar maple sapwood and white spruce heartwood under vacuum
    (Society of Wood Science and Technology, 1999-10-02) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    A macroscopic approach based on the water potential concept is proposed to represent the movement of water in wood during continuous vacuum drying. In order to solve the flow equation, the effective water conductivity under vacuum must be known. A new apparatus is proposed to determine this moisture transport coefficient based on the instantaneous profile method, where moisture content profiles are established at different drying times, making possible the measurement of the moisture flux and driving force at a given position. One-dimensional moisture flow measurements were conducted through two sides of a cubic wood specimén under constant temperature and absolute pressure. The effective water conductivity function was established from green to dry conditions at 60°C in the radial and tangential directions; at 8, 13, and 18 kPa for sugar maple sapwood; and at 8 kPa for white spruce heartwood. The results show that the effective water conductivity decreases exponentially from green conditions to about 35% moisture content for sugar maple. Beyond this point, the effective water conductivity decreases more gradually with a decrease in moisture content for both sugar maple and white spruce. The effective water conductivity is generally higher in radial than in tangential direction for both species. The results obtained for sugar maple show that the effective water conductivity increases significantly as the pressure decreases. The effect of pressure can be explained by the contribution of the apparent gas permeability. The contribution of the pressure potential to the total water potential can be neglected below fiber saturation point. The flux-gradient relationships obtained at given moisture contents are linear, confirming the validity of the flow equation based on water potential used in the present work.
  • PublicationAccès libre
    Optimization of the thermo-hygromechanical (THM) : process for sugar maple wood densification
    (Dept. of Wood and Paper Science College of Natural Resources North Carolina State University, 2016-08-31) Fu, Qilan; Laghdir, Aziz; Cloutier, Alain
    Densified wood is a promising engineered wood product, especially for heavy-duty applications. This study optimized the temperature and duration of the thermo-hygromechanical (THM) densification process applied to sugar maple (Acer saccharum Marsh.) wood. The response variables studied were compression set recovery and hardness. The THM densification process was performed at three temperatures (180°C, 200 °C, and 220 °C), densification times (450 s, 900 s, and 1350 s), and post-treatment times (900 s, 1350 s, and 1800 s). Response surface methodology was used to analyze the impact of the three parameters. The effect of temperature on the density profile across thickness was also determined. The results suggested that the optimum densification conditions resulting in high hardness and low compression set recovery were obtained at a temperature of 180 °C, a densification time of 1004 s, and a post-treatment time of 1445 s. Additionally, the density of the densified samples was relatively homogeneous across thickness, although it was dramatically increased compared with control samples. However, density did not increase linearly with temperature. A much higher weight loss occurred at 220 °C, resulting in a significant decrease in density and hardness, whereas little compression set recovery was observed for sugar maple densified at this temperature.
  • PublicationRestreint
    Modeling vacuum-contact drying of wood : the water potential approach
    (2007-05-10) Defo, Maurice.; Cloutier, Alain; Fortin, Yves
    A two-dimensional mathematical model for vacuum-contact drying of wood is presented. The moisture and heat equations are based on the water potential concept whereas the pressure equation is formulated considering unsteady state conservation equation of dry air. Most of the model parameters were determined during independent experiments. The set of equations is then solved in a coupled form using the finite element method. The validation of the model is performed using experimental results obtained during vacuum-contact drying of sugar maple sapwood. The experimental and calculated data are in good agreement. Nevertheless, some discrepancies are observed which can be attributed to the boundary conditions used and to the fact that heat transfer by convection was neglected.
  • PublicationAccès libre
    Effects of heat and steam on the mechanical properties and dimensional stability of thermo-hygromechanically densified sugar maple wood
    (Dept. of Wood and Paper Science, College of Natural Resources, North Carolina State University, 2017-10-19) Fu, Qilan; Laghdir, Aziz; Cloutier, Alain
    Effects of heat and steam were investigated relative to the mechanical properties and dimensional stability of thermo-hygromechanically-densified sugar maple wood (Acer saccharum Marsh.). The densification process was performed at four temperatures (180 °C, 190 °C, 200 °C, and 210 °C) with and without steam. The hardness, bending strength, bending stiffness, and compression set recovery of the control and densified samples were determined. The effects of heat and steam on the density profile of the samples across thickness were also investigated. The results suggested that the effects of steam on the mechanical properties and dimensional stability of sugar maple wood were more important than that of heat’s influence. Compared to the samples densified without steam, the samples densified with steam showed higher values for hardness, bending strength, bending stiffness, compression set, and density, but much lower compression set recovery when treatment temperature was below 200 °C. High temperature combined with steam contributed to decreased compression set recovery. The lowest compression set recovery was obtained after the first swelling/drying cycle for all of the treatments. A higher weight loss occurred at 210 °C, which resulted in a noticeable decrease of wood density.