Evaluation of Resin Penetration Effect on Bond Strength in Oriented Strand Board with Using a New Quantitative Method

摘要

Adhesive penetration plays an important role in product performances by increasing the adhesive-adherent contact area and providing the mechanical interlocking. The suggested penetration measurement methods for continues bondlines could not be generalized to particulate composites. Two objects of this study are developing a new quantitative method for measuring the resin penetration in discontinues bondlines and determines that, how the resin penetration influences the bond strength. For this purpose, phenol formaldehyde resin were sprayed on veneer strands. Then the strands were formed into well-organized mats to achieve a uniform structure of oriented strand board. To make a difference in resin penetration, strands were used with three levels of 2%, 6% and 10% for moisture content (MC). Cross-section specimens of each board were observed by epi-fluorescence microscopy. Four parameters were determined to quantify resin penetration patterns by counting the quantity of main anatomical elements of wood which were filled with resin. The penetration was evaluated in core layer of board and in 3 mm distance from core as a middle layer. X-ray densitometry was applied to determine average density of boards in above layers. Internal bonding (IB) test was done according to EN 319. It was found that this method could recognize the significant differences between adhesive penetration in boards produced with different level of strand MC. Penetration increased significantly by 6% and 10% strand MC and the similar trend was found for IB. According to the results, by using this method, it is possible to quantify resin penetration in a particulate wood-based composite made with a well-organized mat. Also it was found that the penetration in core and middle layer has significant correlation with IB.