Over 100 pertinent reports and publications were reviewed on the utilization of bark residues for energy and value-added products. Approximately 10 million bone-dry tonnes of bark residues are produced annually as a by-product from the Canadian forestry industry. Environmental agencies are invoking stricter regulations with regard to landfill disposal and phasing out the use of beehive burners. Hence there is an urgency to find alternative uses for bark residues. Although the use of bark residues in energy systems represents an attractive way to dispose of large quantities, these energy options are curtailed by low gas and electricity prices. A potential short term solution to dispose of large quantities of bark residues is to make the bark non-leachable by a practical method followed by disposal in landfills that accept non-leachable residues. However, this would only be possible in certain areas of the country. A new technology developed by Simco/Ramic Inc. shows good potential to sort out "white wood" from bark residues allowing a higher value-added application for the separated "white wood" such as in MDF. Bark has unique properties compared to wood in that it has a much higher inorganic and polyphenolic content. This facilitates the use of bark for higher-value products albeit these products consume much smaller quantities of bark compared to energy uses. Bark has been found to be an excellent material for agricultural and landscaping uses and has been utilized in this area for many years. Over the years, it has also been utilized as an adhesive filler for plywood glues. Much research has been conducted on other uses for bark and these include oil pollution control agents, adhesives, particleboard additives, frost-insulation materials, biofilter media and an oil drilling mud additive. Because of its unique adhesive properties, a future value-added product could be bark board made without synthetic adhesives. In particular, because of bark board's excellent durability properties, an overlaid bark board could have good market potential for exterior products such as siding. The volatile organic compounds (VOCs) emitted in the high-temperature bark board pressing process could be passed through a biofilter using bark as a medium.
Nous presentons ici une revue des travaux parus jusqu'a maintenant au sujet du comportement mecanique et de la modelisation des contraintes de sechage dans le bois. Notre presentation est articulee en fonction des principaux domaines - transferts de chaleur et de masse, modeles de contraintes de sechage, proprietes mecaniques du bois lors du sechage et modelisation numerique, l'accent etant mis sur les trois derniers domaines. Afin d'identifier les approches presentant le plus de potentiel pour la description mecanique et la modelisation de contraintes du sechage, notre revue est basee sur une compilation bibliographique d'environ 90 titres.
There are six species of poplar native to Canada's forests. One of the most abundant and widely used of the species is the aspen poplar (populus Tremuloides). Aspen has become the most desirable species for the production of oriented strandboard (OSB). Certain sections of Alberta and British Columbia have considerable stands of aspen. The aspen stands also contain varying amounts of balsam poplar (populus balsamifera) and black cottonwood (populus trichocarpa) and various hybrids of the three species. Forintek Canada Corp's Technical Advisory Committee (TAC) was asked by the B.C.Ministry of Forests to establish whether cottonwood could be a suitable furnish for the production of OSB, since it represented a sizeable potential resource in British Columbia. The poplar species are loosely identified by several names and to confirm the actual species we were referred to Mr.Bob Brash, District Manager, Dawson Creek Forest District. Mr.Brash confirmed that the species in question was in fact balsam poplar (populus balsamifera). Balsam poplar is also known as black poplar and balm poplar. An extensive literature search was conducted on the use of balsam poplar/cottonwood in the production of OSB. The literature review and a summary are reported here.