The work described in this report involved examination of the development of IB strength in OSB panels as a function of pressing parameters and mat moisture content. Response surface methodology (RSM) was used in the design the experimental work employing a Box-Behnken design with four (4) variables (platen temperature, pressing time, moisture content (MC) of the face layers of the mat and face/core ratio).
Results showed that the relationships between the study parameters and IB strength fit very well the form of quadratic polynomials. Within the limits studied, it was found that increasing the pressing time and/or temperature could significantly improve the IB strength in OSB panels. Also, the study showed that bonding strength is improved by reducing mat moisture content.
It recommended that the study proceed as planned, using a thermal analysis technique (DSC) to compare the chemical reactions and curing behaviour of some commercial PF resins. Also, lap-shear tests, will be employed to evaluate strength development of the adhesives as function of time, temperature and furnish moisture content. It also recommended that a bench-making will be proceeded at laboratory and mill scale to verify the model.
Les facteurs clé à la source du gauchissement des panneaux ont été identifiés suite à une revue de littérature exhaustive. Les méthodes pour mesurer ces variables ont été soit identifiées dans la littérature soit mises au point au laboratoire de l'Est de Forintek. les méthodes de laboratoire incluent la mesure du gauchissement ainsi que celle des gradients des propriétés suivantes : densité; module d'élasticité; dilatation linéaire; teneur en humidité. Des gauchissements ont été induits en laboratoire sur des panneaux de diverses configurations et ces variables ont été mesurées. Les expériences ont permis de construire une base de données sur le comportement ds panneaux agglomérés en fonction des variations de conditions ambiantes. La base de données a ensuite été utilisée pour vérifier la comformité des phénomènes observés avec les meilleurs modèles de prédictions disponibles.
Part 1 : Plywood press emissions as a function of panel processing parameters were evaluated by means of a laboratory caul plate press stack collection system. Panel pressing temperatures were 140, 150 and 160°C and pressing times 7, 9 and 11 minutes. Glue spreads in terms of resin solids were 0.033, 0.040 and 0.046 lbs/ft² (161.46, 193.75, 226.04 g/m², respectively). Response surface methodology (RSM) with the Box and Behnken design was used to define the minimum number of experimental points needed to fully represent a quadratic regression model. A total of 15 experimental points and 3 extra centre points was determined leading to an incomplete 33 factorial design. Results indicated that plywood press emissions are affected by processing parameters in different ways depending on the type of the volatile organic compound of interest. The quadratic RSM models in terms of the coded factors showed that formaldehyde emissions were more sensitive to pressing time while methanol and total volatile organic chemical (TVOC) emissions were more sensitive to resin content. However, an increase in any processing parameter resulted in an overall increase in press emissions. On the other hand, the amounts of formaldehyde and TVOC emitted from the resulting plywood panels were more sensitive to resin solids content than to pressing temperature or time, showing decreases with increasing resin contents. The use of an optimization procedure based on the geometric mean of each response desirability function allowed multiple solutions with minimum press emission levels with a desirability value of up to 0.97 when the imposed limits during the optimization procedure were less stringent. The ideal desirability value is 1.0.
Part 2 : A laboratory method was developed to evaluate the effects of key wood particleboard processing parameters on hot-press emissions of volatile organic compounds (VOCs). The method was based on an enclosed caul plate system that trapped the gas stream containing the VOCs emitted during board pressing. The hot gases trapped in the caul plate were cleaned through cold traps containing distilled water or organic solvent for non-water-soluble chemicals, in order to condense and trap VOCs from the air stream. Formaldehyde was quantified by the chromotropic acid method (NIOSH* modified method), while methanol and phenol were quantified by gas chromatography/flame ionisation detection (GC/FID. Other VOCs were characterised and quantified by gas chromatography/mass spectroscopy (GC/MS). Formaldehyde emissions as well as methanol, phenol and total volatile organic compound (TVOC) emissions, which consisted mainly of terpenes, increased with platen temperature, pressing time and mat resin solids content conversely, subsequent emissions from the panels themselves decreased. Inversely, panels produced showed decreasing emission levels when processing parameters such as resin content, pressing time and pressing temperature were increased. Furnish composition significantly affected press emissions in terms of both nature and amount of chemicals emitted. The surface moisture content of the mat also seems to increase press emissions but further work needs to be conducted to support this observation. This includes works on the response surface methodology in the study of plywood press emissions of volatile organic compounds; Press volatile organic compound emissions as a function of wood particleboard processing parameters
Le présent rapport traite de l'utilisation de panneaux alvéolaires, ou "géocellulaires", pour former des murets de soutènement dans l'installation de ponceaux et pour stabiliser les pentes. FERIC a planifié et participé à l'installation de panneaux géocellulaires de marque Geoweb dans deux opérations et a constaté que, même si ces matériaux coûtent plus cher que d'autres solutions, ils sont faciles à installer, efficaces et économiques dans des conditions de site appropriées.