Abstract
When a formulated fungicide containing N-cyclohexyldiazeniumdioxy potassium (KHDO) and fenpropimorph was simultaneously sprayed onto strands with the resin, using a separate spray line, the resulting waferboard durability was enhanced against both brown and white rot fungi. The mass losses of the test blocks cut from the boards manufactured with different concentrations of fungicide and exposed to four decay fungi, suggest that the target retention of 0.44% KHDO and fenpropimorph (based on the oven dry weight of the strands) provided the same protection against two white rot (T. versicolor and P. ostreatus) and two brown rot fungi (G. trabeum and P. placenta) as waferboard which incorporated 0.83% zinc borate. The fungicide was most effective against the brown rot fungi, at a concentration of 0.29% KHDO and fenpropimorph. For the two white rot fungi, the toxic threshold was determined to be 0.44% (KHDO and fenpropimorph). At all concentrations the fungicide had no adverse effect on the static bending strength or stiffness of the waferboard, but caused a slight (17%) loss in mean internal bond strength.
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