Journal of Environmental Biology

Adhesive bond performance of heat-treated wood at

various conditions

Hamiyet Şahin Kol* and G?nay ?zbay

 Department of Forest Products Engineering, Forestry Faculty, Karab?k University, Karab?k-78050, Turkey

*Corresponding Author E-mail: hsahinkol@karabuk.edu.tr

Publication Data

Paper received:

21 April 2015

Revised received:

04 November 2015

Re-revised received:

24 November 2015

Accepted:

20 January 2016

Abstract

Heat treatment of wood leads to chemical, structural and physical changes in wood constituents, which can significantly affect the bonding performance of wood in several ways depending on the adhesive type used. In the present study, fir (Abies bornm?lleriana Mattf.) and beech (Fagus orientalis L.) were heat treated at 170 ^?C, 180 ^?C, 190 ^?C, 200 and 212 ^?C for 2 hours. Four different types of adhesives were used for bonding process: melamine-urea-formaldehyde (MUF), melamine formaldehyde (MF), phenol formaldehyde (PF), and polyurethane (PUR). For all the pretreatment conditions, highest shear strength of adhesive bonds of each adhesive system was observed for untreated samples and shear strength decreased with increasing heat treatment. The strength of each adhesive bond of samples which were soaked in water was much less than dry samples, approximately half of the dry strength. Generally, the shear strength of the adhesive bonds after boiling was smaller than or similar to the values obtained for soaking. The untreated samples lost more strength after soaking and boiling than heat treated samples. With increasing heat treatment severity, reduction in shear strength increased in dry samples while decreased in soaking and boiling samples. For instance, after soaking, the untreated samples lost more strength (almost 39%) than heat treated samples (almost 24% for most severely heat treated samples). The results showed that the shear strength of adhesive bonds was influenced by heat treatment and depended on pretreatment of samples prior to testing. In general, all adhesives used performed in quite a similar way for all pretreatment conditions, and the bonding performance of heat treated fir wood was less satisfactory than that of beech wood for all adhesive system and condition.?        

 Key words

Adhesive bond, Boiling, Heat-treated wood, Shear strength, Wood adhesive

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