Hendrikus W. G. van Herwijnen

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Changes in formaldehyde emission guidelines led to changes in the resin formulation. These changes include reduced formaldehyde to urea molar ratio which is followed by a change in reactivity of aminoplastic resins. This resulted in an increased occurrence of an undesired type of tack, herein called “sticking”, which causes addition of resinated wood(More)
Ammoxidation of pine kraft lignin in aqueous 5 wt % ammonia affords a novel type of phenol substitute that significantly accelerates resole synthesis and curing as demonstrated for 40 wt % phenol replacement. Compared to non-ammoxidized lignin, which already shortens significantly the cooking time required to reach a resole viscosity of 1000 Pa·s (250 vs.(More)
A previously developed rheometer-based method to examine undesired cold tack (“sticking”) of aminoplastic resins to machinery parts was further modified to enable climate depending measurements. It could be shown that both relative humidity and temperature influence sticking, resulting in a variation in the extent of sticking as well as in the time window(More)
A new procedure to detect urea–formaldehyde adhesive in industrial particle board is presented. The method uses thin sections stained with a visible dye (gentian violet) and a fluorescent dye (brilliant sulphaflavine), respectively, in a two-step procedure. Microscope images of a selected area of interest acquired in visible and fluorescence modes are(More)
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