Bond strength and durabilty behavior of polyurethane-based Desmodur-VTKA adhesives used for building materials after being exposed to water-resistance test

摘要

Polyurethane adhesives are being used increasingly in the construction of furniture frames and buildings. Yet, there is little information available concerning the durability behavior of polyurethane adhesives on various wood species, after being exposed to water-resistance test. For this purpose, oriental beech (Fagus orientalis L.), oak (Qercus petraea spp.), and scotch pine (Pinus sylvestris lipsky) woods were chosen as test materials and bonded with Desmodur-VTKA polymarine, according to the procedure of BS EN 204 standards. The shear strength test was applied to the samples, according to the procedure of BS EN 205 standards, before and after immersion in cold water and in hot water, and afterward boiled and boiled recurrently. At the end of the shear test, it was found that Desmodur-VTKA polymarine had lost its durability. The highest shear strength (10.723 N/mm(2)) was obtained in oak samples not exposed to water-resistance test. Owing to dissimilar swelling of Desmodur-VTKA polymarine and oak, resulting from moisture sorption, oak samples lost 85.6% of its strength after being boiled and boiled recurrently, and gave the lowest shear strength as 1.540 N/mm(2). As a result, if Desmodur-VTKA is used as an adhesive material in the long-term humidity condition, it cannot be recommended for bonding of wood materials with high density. (c) 2006 Wiley Periodicals, Inc.