ADHESIVE PROPERTIES OF LAMINATED WOODS CO MPOSED OF SOFTWOOD AND HARDWOOD

The dependence of adhesive properties on wood combinations was examine d by the use of various wood species. The combinations were softwood/s oftwood, hardwood/hardwood, and softwood/hardwood which were bonded wi th resorcinol-formaldehyde resin (RF) and aqueous polymer solution-iso cyanate resin (API). For the laminated wood composed of different wood species, dry strength and water resisting properties based on Japanes e Agricultural Standard (JAS) were related to those of laminated wood composed of the constituent species alone without larch (Larix leptole pis Gord.). Wet/dry cyclic (WDC) treatment had a much greater effect o n specimens with RF than on those with API. This is because the durabi lity depends on the mechanical properties of the adhesives: API deform s with swelling and shrinking, whereas RF does not. From a comparison of laminated wood composed of different wood species and that of one s pecies alone, it was found that the durability to a WDC treatment does not depend only on such properties of adhesives but also on other fac tors, especially water movement and moisture gradient.