Abstract
This study was conducted to test the strength of glue line in wood structures by using some mechanical tests (shear strength test, Dry and wet tensile tests). Two kinds of adhesives (Urea-formaldehyde (UF) and poly-vinyl acetate (PVA) with three types of wood surfaces (Pure Pine, Pure Sycamore and substrate of Pine with Sycamore) and two methods of adhesive curing (Electrical and microwave domestic ovens) were used. It was shown from the study results that wood type had an effect in share tension test, pine wood gave the best results followed by shear tension of sycamore wood and pine with sycamore wood, but there were no significances between the three types of woods. Urea formaldehyde adhesive got the highest shear tension values when compared with PVA adhesive. Solidification by using electrical oven method gave the best values in shear tension as compared with the microwave oven curing method. The results also showed that 1 gm adhesive quantity gave the best results as compared with 0.75 gm and 0.5 gm in shear tension. Concerning the dry and wet tensile tension of the PVA glue line by using electrical oven dry, microwave oven and room temperature solidification methods, the results showed that pine wood had greater dry and wet tensile tension than sycamore wood and pine with sycamore wood. Also, parallel grain direction gave the best values as compared to perpendicular grain direction for both dry and wet tensile tension. The results also showed that the highest dry tensile tension was by using electrical oven solidification method، followed by room temperature method، while solidification by using microwave oven gave the lower tensile tension value. Room temperature solidification method gave the best results in tensile tension after emersion in water for 30 and 60 minute as compared to electrical oven and microwave oven solidification process respectively. Also, 2 gm adhesive gave the best results in tensile tension compared to 1.5 gm and 1 gm adhesive quantities.
