Plywood is valued for its uniform strength in all directions. This gives plywood an upper hand against solid wood in terms of cracking and warping. In Estonia, only birch is used for plywood production. On the other hand, birch logs prices are rather expensive compared to alternatives. This leaves us few species that are much cheaper than birch logs and at the same time promising to be comparable match by mechanical properties. Therefore, topic is very actual, to consider cheaper species in value adding manufacturing.
The aim of the research is to determine the effect of replacing some birch layers with alder wood and how mechanical properties are changed due that. As plywood structure is even, then changing plies direction is having impact on mechanical properties. Second aim of the research is to determine the effect of adding consecutive plies in same direction. For sustainable manufacturing, there is strong demand to remove formaldehyde from resins, as it is toxic and carcinogenic material. Therefore, in this research lignin substituted phenol formaldehyde adhesive is used for comparison to traditional phenol formaldehyde glue.
Keywords: Plywood, mechanical properties, adhesive
Authors
Heikko Kallakas
Tallinn University of Technology, Estonia, Laboratory of Wood Technology, Department of Material and Environmental Technology
Harti Vahermets
Anti Rohumaa
Triinu Poltimäe
Jaan Kers
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