Hardwood species bonding properties after cyclic changes of environmental conditions

The focus of this research was to investigate the bonding quality of the adhesives type after exposure to various moisture and temperature changes. This exposure was to simulate the changes in the interior application, which can cause problems in furniture manufacturing, especially with the usage of different adhesives. Different types of adhesives (Polyvinyl acetate (PVAc), Polyurethane (PUR), urea-formaldehyde (UF), and melamine-urea-formaldehyde (MUF)) were tested for bonding quality on two hardwood species; European beech (Fagus sylvatica L.) and English oak (Quercus roburL.). Bonding quality was tested based on EN13354 standard for control specimens, after 8 and 16 cycles of moisture and temperature changes. There was no statistical difference in bonding quality for the PVAc adhesive on beech and oak wood. PUR adhesive showed a significant decrease in the bonding quality of beech wood and no change in oak wood after exposure. The highest reduction in bonding quality after exposure cycles was found in the UF adhesive due to hydrolysis of the adhesive, regardless of the wood species. There was only reduction in the bonding quality for the MUF adhesive for beech wood after 16 cycles of the exposure condition.