Elastic Properties of Oak Wood Finger Joints with Polyvinyl Acetate and Isocyanate Adhesives

Abstract

In this study, the elastic properties of 23 specimens of oak timber (Quercus castaneifolia), including the longitudinal modulus of elasticity (MOE), acoustic coefficient (K), and acoustic converting efficiency (ACE) in free vibration using the free-free beam method with different planes of vibration, i.e. tangential (LT) and radial (LR), were studied. These elastic parameters were examined in both sound wood and finger jointed timbers with two different lengths of fingers (5- and 10-mm finger lengths) and individually glued with two different types of adhesives (isocyanate and polyvinyl acetate). Comparing the elastic properties of solid beams with finger jointed beams of oak wood in both (LT) and (LR) planes, 10-mm finger joints with polyvinyl acetate adhesive did not cause any serious change to the studied elastic properties of the beams, while shorter finger length (5 mm) with isocyanate adhesive severely changed the acoustic properties; therefore, beams having longer finger lengths may have enhanced acoustical properties.