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Dynamic mechanical analysis of urea formaldehyde resin modified by ammonium pentaborate as wood adhesive
Author(s) -
Gao Wei,
Du Guanben,
Ma Hong,
Li Jianzhang
Publication year - 2016
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.23422
Subject(s) - urea formaldehyde , materials science , molar ratio , formaldehyde , hexamethylenetetramine , adhesive , molar , ammonium , composite material , bond strength , dynamic mechanical analysis , urea , nuclear chemistry , chemistry , organic chemistry , catalysis , medicine , polymer , dentistry , layer (electronics)
Urea formaldehyde (UF) resins with varied molar ratio of formaldehyde (F) to urea (U), modified by ammonium pentaborate (APB) at different loading level, was analyzed by dynamic mechanical analysis (DMA) and evaluated via bonding properties of its glued plywood. The result indicated that a higher loading of APB made a slower gelling and improved the Δ E ′ (the difference of storage modulus) of UF resin with F/U molar ratio of 1.8. Hexamethylenetetramine, generated from the ammonium ion in APB and formaldehyde in UF resin and characterized by the covalent bond connections, was considered as the main reason to improve the rigidity of the cured UF resin system. The bond strength result confirmed the DMA analysis that the addition of APB improved bonding performance of UF resin with higher F/U molar ratio such as 1.8. A specific recommendation loading level of APB was made to modify UF resins, of which 6.0 to 8.0% APB should be used to modify UF resin with F/U molar ratio of 1.8, then 6% and 4% loading level of APB to UF resin with F/U molar ratio of 1.50 and 1.25, respectively. Finally, APB was n'ot suggested to modify UF resin at F/U molar ratio less than 1.20. POLYM. COMPOS., 37:2404–2410, 2016. © 2015 Society of Plastics Engineers