Physical properties of plywood during prolonged water exposure

Abstract

Тhe aim of this research is to study the physical properties of experimental plywood bonded with alcohol-soluble phenol-formaldehyde resin during prolonged water exposure. On the basis of the obtained data for the changes of the physical properties of plywood after exposure to prolonged water treatment of 192 days, water resistance of experimental plywood is evaluated. Tests for the thickness swelling, volume swelling and water absorption are made after immersion in water for prolonged period in controlled laboratory conditions. The measuring of thickness, length, width and mass of plywood test specimens for determination of these properties is made after immersion in water for the period of 1 day (24 hours) to 192 days (4608 hours). Plywood model in this experiment was made from peeled beech veneers bonded with pure alcohol-soluble phenol-formaldehyde resin. The results from the research showed that the plywood model is characterized by uniform density; it is dimensionally stable during and after prolonged water exposure, without any deformations of the shape of the test specimens. The changes of the values of thickness and volume swelling, as well as the values of water absorption in the analyzed period are proportional to change of the duration of the period of water exposure. According to the obtained data from the tests of these properties the plywood model meets the requirements for load-bearing plywood for use in construction.