@article {1709,
	title = { Comparison of the properties of urea-formaldehyde resins by the use of formalin or urea formaldehyde condensates },
	journal = { JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY },
	volume = {32},
	year = {2018},
	pages = {2537-2551},
	abstract = {<p>In industry, formalin and urea formaldehyde condensates (UFC) are used for the preparation of urea-formaldehyde adhesives. The aim of this study was to evaluate the characteristics of a UF resin prepared with formalin (42\% concentration) and two kinds of UFC with various urea content (F/U similar to 5 and 4.3 malar ratio). The resins were prepared with final molar ratio F/U = 1.1. The UF resin with formalin showed better mechanical properties than those with UFC. The C-13 NMR and FT-IR results indicated that methylene, methylene ether and urons groups in a UF resin prepared with formalin were present in higher proportion than observed in industrial UF resins. The DSC (differential scanning calorimetry) results showed that the curing temperature of a UF resin prepared with formalin is lower than that of a UF resin prepared with UFC. The mechanical properties of MDFs prepared with the three types of adhesives showed that MDFs bonded with a UF prepared with formalin yields a better mechanical properties than MDFs prepared with a UF resin based on UFC. Moreover, resin synthesized with UFC (F/U = 5) result in higher IBS (internal bond strength) MOR (modulus of rupture), MOE (modulus of elasticity), TS (thickness swelling) and formaldehyde emission (FE) than resin synthesized with UFC (F/U = 4.3). The MDF bonded with the UF2 resin presented poor results, with the highest TS and the lowest IBS, MOE, MOR and FE.</p>},
	author = {A. DORIEH and N. MAHMOODI and M. MAMAGHANI and A. PIZZI and M.M. ZEYDI}
}
