Variation in wood pH and its impact on resin cure in oriented strand board, OSB

grantor: University of TorontoThe variation of pH was investigated in wood strands and log sections of aspen and birch in relation to certain process parameters employed in the manufacture of oriented strand board (OSB). Mine member mills of the Structural Board Association provided green and dry wood strands from winter and summer harvested logs. The acidity of samples from summer harvest was higher than those from the winter. Wood acidity increased with drying temperature and time, as well as duration of storage. A negative correlation was found between wood pH, acid buffering capacity and gelation time with four different phenol-formaldehyde resins. The internal bond strength of laboratory made boards was positively correlated with strand pH. This study demonstrated that wood acidity had a marked influence on the curing of phenol-formaldehyde resins and on the adhesive bonding of wood. It should not be construed, however, that wood acidity is the only factor affecting its bonding.M.Sc.F