Personne : Landry, Véronic
En cours de chargement...
Date de naissance
Projets de recherche
Nom de famille
Université Laval. Département des sciences du bois et de la forêt
Résultats de recherche
Voici les éléments 1 - 10 sur 30
- PublicationAccès libreRevêtements nanocomposites à haute teneur en solide cuits aux ultraviolets pour les couvre-planchers en bois(2009) Landry, Véronic; Riedl, Bernard; Blanchet, PierreLes revêtements à haute teneur en solide cuits aux ultraviolets sont présentement utilisés par la très grande majorité des industries produisant des couvre-planchers en bois pré-vernis. Leurs propriétés mécaniques exceptionnelles, de même que leur vitesse de cuisson nettement plus élevée que celle des autres types de revêtements, expliquent leur grande popularité. Or, il est possible d’obtenir des propriétés mécaniques, entre autres, encore plus impressionnantes par l’addition de différents renforts. Dans ce projet, des oxydes métalliques nanométriques (oxyde d’aluminium et oxyde de zirconium) de même que des argiles modifiées avec des groupements organiques ont été ajoutés à une formulation acrylate typique de l’industrie des revêtements de couvre- planchers en bois. Les nanoparticules ont été ajoutées et dispersées dans cette formulation à l’aide de différents appareils de dispersion : mélangeur haute vitesse, moulin à billes (bead mill), moulin à balles (ball mill) et moulin trois rouleaux (three roll mill). Suite à la préparation des revêtements nanocomposites, la taille des particules dans la matrice polymère a été étudiée à l’aide de différents appareils. Pour les oxydes métalliques, la diffusion dynamique de la lumière a été utilisée. Pour ce qui est argiles, la diffraction des rayons X aux petits angles a quant à elle été employée. Dans les deux cas, nous avons eu recours à la microscopie électronique à transmission afin de supporter ces données. Quelques essais supplémentaires tels des mesures de stabilité et de viscosité sont aussi venus supporter les résultats obtenus. L’addition de nanoparticules affecte généralement la cuisson des revêtements UV. La spectroscopie infrarouge en temps réel (RT-FTIR) de même que la photo-calorimétrie (photo-DSC) ont été employées afin d’étudier les changements apportés à la cuisson suite à l’addition de nanoparticules. Finalement, les propriétés optiques (brillance, voile, couleur et clarté optique) et mécaniques (dureté, résistance à l’abrasion, résistance à l’égratignure, résistance à l’impact et à l’impact inverse) des différentes formulations ont été étudiées. Pour les formulations préparées à base d’argile, une analyse de variance (ANOVA) a été réalisée afin de vérifier si la concentration de l’argile de même que la façon dont celle-ci a été ajoutée à la formulation de base affectent les propriétés finales des revêtements.
- PublicationAccès libreEvaluation of environmental impacts of citric acid and glycerol outdoor softwood treatment : case-study(Elsevier, 2017-06-18) Essoua Essoua, Gatien Géraud; Landry, Véronic; Beauregard L., Robert; Blanchet, Pierre; Ben Amor, MouradOver the last few decades, wood modification has been performed to improve wood product technical performance. Using renewable based chemicals for wood modification is an innovative alternative to the non-renewable petrochemicals commonly used. However, it should be kept in mind that having the raw material from renewable sources does not guarantee zero environmental impacts. In this study, the treatment considered uses citric acid and glycerol mixture; two chemical products derived from renewable sources. In the residential building context of Quebec-Canada, the cradle-to-grave life cycle assessment for untreated and treated lodgepole pine wood siding was performed and compared. The results obtained show that the treated wood siding has higher environmental impacts than the untreated wood siding, in spite of its longer service life. This is partially caused by the high contribution of citric acid production used for treatment. The current service life expectancy of treated wood siding was estimated to be 2.8 times longer than the one of untreated wood siding based on standardized durability test and classification (AWPA E 10–12 and ASTM D 2017-05). Sensitivity analysis showed that life cycle impacts of treated wood siding become lower than those from untreated wood siding when service life expectancy reaches 5-times that of untreated wood siding. Life cycle assessment could be used for guidance in developing better treatments to improve their environmental impacts.
- PublicationAccès libreDetermination of in situ esterification parameters of citric acid-glycerol based polymers for wood impregnation(Kluwer Academic/Plenum Press, 2017-04-08) Bérubé, Marc André; Schorr, Diane; Ball, Richard J.; Landry, Véronic; Blanchet, PierreThe development of wood treatments is of increasing industrial importance. A novel technique for improving the properties of lodgepole pine and white pine through modification of the microstructure is described. The present investigation is devoted to the synthesis and determination of in situ parameters of citric acid and glycerol based polymers for wood impregnation. This solvent free approach is environmentally friendly and achieved through an esterification condensation reaction under acidic conditions. Crude glycerol and citric acid reactants were cross-linked via a curing process at 160 °C creating a polymer with only water as the byproduct. The ester bonds and crosslinking levels were controlled using different catalysts and citric acid contents and related to the reaction time and temperature. The nature of bonding within the polymers and at the wood cell walls was determined by FT-IR analysis. The thermal properties such as glass transition temperature (Tg) were studied using TGA/DSC and the effect of citric acid content and catalyst type determined. Dimensional stability of impregnated wood samples improved above 50% for each sample with HCl and p-TSA catalysts compared to control samples. FTIR spectra were studied to show the presence of the ester linkages of the polymer in situ at the wood cell walls. Bonding between the polymer and wood macromolecules were observed by scanning electron microscopy and interpreted as evidence of chemical bonds at the wood cells. When prepared using a catalyst, the polymer was intimately incorporated into wood structure significantly improving the substrate dimensional stability. Enhanced stability makes this approach of particular interest for exterior wood products especially as a green renewable option for the wood industry.
- PublicationAccès libreUV-LED curing efficiency of wood coatings(MDPI, 2015-12-18) Bouffard, Jean-François.; Boivin, Gabrielle; Landry, Véronic; Vlad-Cristea, Mirela Simona; Blanchet, PierreUltraviolet light emitting diodes (UV-LEDs) have attracted great interest in recent years. They can be used to polymerize coatings, such as those used for prefinished wood flooring. In this project, two lamps were compared for their suitability to be used on a wood flooring finishing line: a UV-microwave and a UV-LED lamp. Low heat emission was found for the UV-LED lamp compared to the UV-microwave one. This study also reveals that the 4 W/cm2 UV-LED lamp used is not powerful enough to cure UV high solids acrylate coatings while satisfactory results can be obtained for UV water-based formulations. In fact, conversion percentages were found to be low for the high solids coatings, leaving the coatings tacky. Higher conversion percentages were obtained for the UV water-based formulations. As a result, mass loss, hardness, and scratch resistance found for the samples cured by UV-LED were closed to the ones found for the samples cured using the UV microwave lamp.
- PublicationAccès libreImpact of indoor use of wood on the quality of Interior ambiances under overcast and clear skies : case study of the Eugene H. Kruger Building, Québec city(Dept. of Wood and Paper Science, College of Natural Resources, North Carolina State University, 2016-01-06) Demers, Claude; Landry, Véronic; Jafarian, Hoda; Blanchet, PierreThis paper explores the potential of wood for improving environmental quality in interior spaces. In northern climate cities where overcast skies predominate, interior spaces may appear gloomy or dull, since natural light is white and uniform. Nevertheless it is observed that wooden surfaces tend to create warmer and brighter spaces under overcast sky conditions. The objectives of this research were twofold. The first was evaluating the quality of wooden spaces under two sky conditions in terms of color, brightness and contrast. The second objective was to investigate daylight quantity of wooden spaces under diffuse and clear sky conditions. The method involved on site-surveys using Photolux, a calibrated photoluminance meter. Data consist of calibrated digital images that were processed to analyze the quality of spaces based on brightness, contrast, and color. The Kruger Building, with its internal wooden architectural structure and decorative indoor panels, was chosen as a site study for this research. Conclusions suggest that knowing the effect of different sky conditions on wooden spaces can help architects and other professionals in designing more comfortable and efficient ambiances. More particularly, this research addresses issues related to the quantitative effects of wood on daylighting distribution, visual comfort and luminance diversity
- PublicationAccès libreMaleic anhydride treated wood : effects of drying time and esterification temperature on properties(Dept. of Wood and Paper Science, College of Natural Resources, North Carolina State University, 2015-08-26) Essoua Essoua, Gatien Géraud; Landry, Véronic; Beauregard L., Robert; Blanchet, PierreTo improve technical performance of wood siding, treatment with maleic anhydride was applied. The effects on technical performance of drying time and esterification temperature parameters were analyzed. Wood samples of lodgepole pine and white pine were treated and tested. Results indicated that treatment improves technical performance of wood (dimensional stability, fungal degradation resistance, and accelerated aging). FTIR spectroscopy analysis showed spectra with peaks at 1750 to 1730 cm-1. These correspond to ester bonds formed between wood hydroxyl groups and MA carboxylic groups. SEM images indicate that the MA quantity in wood cavities was increased with decreasing esterification temperature. Weight percent gain (WPG) increased with decreasing time and temperature of esterification. Artificial aging and fungal degradation performances were monitored using FTIR analysis. Esterification temperature had no important effect on fungal degradation. Weight loss after fungal exposure of treated samples was not only due to fungal action but also due to evaporation of MA during the drying step. Regarding artificial aging, degradation of wood components and ester bonds were less for samples esterified at 180 °C than those esterified at 160 °C or 140 °C.
- PublicationAccès libreImpact of a reinforcement treatment with acrylate impregnation on the mechanical behavior of black spruce as connector member.(Elsevier, 2017-03-14) Lafond, Cassandra; Galimard, Philippe; Landry, Véronic; Blanchet, Pierre; Ménard, SylvainAs a previous study has shown, it is possible to increase by 50% the dowel bearing strength of black spruce with an acrylate formulation applied by impregnation. Three diameters of bolts and two orientations of loading were included in this study. The effect of treatment on the dowel-bearing strength appeared to increase while the diameter of bolt decreased. The orientation of loading was significant as the treatment had a major impact in the parallel to grain direction and no impact in the perpendicular direction. With the digital image correlation analysis, an expanded strain field perpendicular to the load direction was observed. The superior embedding capacity would help to reduce the dimensions of the timbers as well as the number of connections required in the building design. With an increase of ductility, wood connections show a safer yielding behavior.
- PublicationRestreintEffects of interior wood finishes on the lighting ambiance and materiality of architectural spaces(Sage, 2017-02-09) Demers, Claude; Landry, Véronic; Jafarian, Hoda; Blanchet, PierreWood is a material often used by architects to enhance the overall ambience of a space, but few researches have been reported to discuss its actual impact on visual impression and luminous effects. This research studies the influence of wood materiality in relation to creating specific lighting ambiances in architecture. In particular, it focuses on the impact of decorative wood indoor panels on the creation of daylighting diversity in interior space and the potential to improve daylighting quality and energy efficiency. The research uses scaled models for their accuracy in rendering complex daylighting ambiances. The photo-luminance meter enables the comparison between different settings of interior spaces created by a selection of wood type materiality: ratio (percentage), colour (Oak, Cape Cod Grey and Dark Walnut coatings) and gloss concerning illuminance patterns obtained from Ecotect software. The CIE L*a*b* colour space is used to classify luminous ambiances. Results indicate that bright colour Oak favours a deeper daylighting penetration and increases the colour temperature of the space by about 300% when applied on the floor. Cape Cod Grey coating provided a neutral colour balance even under sunlighting. High gloss Dark Walnut located on the ceiling produces the highest luminance values, enlarging the window-lighting pattern. The research underlines the role of wood materiality in achieving luminous diversity and creating visually comfortable interior ambiances.
- PublicationAccès libreThe multifactorial aspect of wood weathering : a review based on a holistic approach of wood degradation protected by clear coating.(North Carolina State University. College of Natural Resources, 2017-11-22) Landry, Véronic; Cogulet, Antoine; Blanchet, PierreWood is an abundant and renewable natural resource. Its use is promoted as a way to reduce the carbon footprint in building construction. Wood structures are degraded by their environment due to weathering. This review is a meta-analysis of the main factors of degradation that belong to this phenomenon. The impact of irradiation, the role of water, oxygen, temperature, and colonization by fungi are explained. To protect against these factors, the use of coatings is the most common solution. Since currently the trend is to maintain the grain and the natural color of the wood, the use of transparent coatings is favored. This review presents the main technologies used in clear wood coatings. The durability of this protection against weathering is approached. The whole of knowledge gathered has made it possible to begin a discussion on the multifactorial aspect of wood weathering. Schemes were created to synthesize the synergistic and antagonistic effects between the degradation factors.
- PublicationAccès libreEffect of adding UV absorbers embedded in carbonate calcium templates covered with light responsive polymer into a clear wood coating(MDPI AG, 2018-07-28) Schorr, Diane; Queant, Caroline; Landry, Véronic; Blanchet, PierreThe limited durability of clear coatings is a major issue for the coating and wood industry. The addition of organic UV absorbers improves coating resistance by the absorption and the conversion of the UV radiation into harmless heat. Organic UVAs are prone to degradation and can migrate in the binder of coatings. In this study, commercial UVAs and HALS have been entrapped into CaCO3 templates coated with stimuli responsive polymers. Microspheres were incorporated into a clear acrylic water-based coating formulation. The formulation was applied on glass and wood panels and was placed into an artificial UV chamber. This study presents a comparison between the aesthetic behavior of coating formulations with free and encapsulated commercial UVAs and HALS during the accelerated ageing test. Encapsulation of UVAs was confirmed by XPS and TGA analysis. Results have shown that the coating’s aesthetic was slightly improved when using the encapsulated products.
- 1 (current)