CONNECTION PERFORMANCE OF LENGTH-WISE FINGER-JOINTED EUCALYPTUS
The high density and large amount of extractives of eucalyptus (Eucalyptus maculata) wood are very unfavorable for the production of its finger-jointed timber. This study examined the mechanical properties of finger-joint nodes during the pressing and unloading processes at the ends, and investigated the effects of chemical agents and heat treatment methods on the performance of finger-joint connections. The results indicated that high end-pressure was crucial for maintaining the stability of finger joints, as a reduction in pressure led to significant displacement relaxation and springback. The high extractive content in eucalyptus had different effects on the bonding performance of different adhesives: polyvinyl acetate (PVAc) adhesive exhibited superior bonding performance, with tensile strength and flexural strength reaching 12.21 MPa and 52.61 MPa, respectively. Furthermore,heat treatment and anhydrous ethanol pretreatment can effectively reduce the impact of extractives at the joint interface, thereby enhancing the bonding strength. Compared to untreated controls, heat treatment improved tensile and flexural strength by 5.7% and 0.6%, respectively, while anhydrous ethanol pretreatment resulted in increases of 3.8% and 7.6%.