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Dynamic mechanical analysis of urea–formaldehyde resin adhesives with different formaldehyde‐to‐urea molar ratios
Author(s) -
Park ByungDae,
Kim JaeWoo
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.27595
Subject(s) - adhesive , urea formaldehyde , molar , dynamic mechanical analysis , materials science , curing (chemistry) , formaldehyde , composite material , molar ratio , urea , nuclear chemistry , polymer chemistry , chemistry , organic chemistry , catalysis , polymer , dentistry , medicine , layer (electronics)
As a part of abating formaldehyde emissions of urea–formaldehyde (UF) resin adhesives, using dynamic mechanical analysis (DMA), we attempted to investigate the influence of the formaldehyde to urea (F/U) molar ratio on the thermomechanical curing of UF resin adhesives with different F/U molar ratios. The thermomechanical curing of these UF resin adhesives was characterized with DMA parameters such as the gel temperature, maximum storage modulus, peak temperatures of the storage and loss moduli, and maximum tan δ. As the F/U molar ratio decreased, the gel temperature of UF resin adhesives increased, whereas the maximum storage modulus, an indicator of the rigidity of UF resin adhesives, decreased. The maximum tan δ increased with the F/U molar ratio decreasing, and this indicated that the UF resin adhesive with a low F/U molar ratio had greater damping than the one with a high F/U molar ratio. A decrease in the rigidity of the UF resin with a lower F/U molar ratio was explained by the calculated crosslinking density, which decreased with the F/U molar ratio decreasing. These results partially explained why UF resin adhesives with lower F/U molar ratios showed relatively poor adhesion performance when they were applied to the manufacture of wood panels. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008