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Author(s): João M. M. Ferra
Ana Henriques
Adélio M. Mendes
Mário Rui N. Costa
Luísa H. Carvalho
Fernão D. Magalhães
Title: Comparison of UF synthesis by alkaline-acid and strongly acid processes
Issue Date: 2012
Abstract: This work discusses two processes for producing urea-formaldehyde (UF) resins. One is the alkaline-acid process, which has three steps: usually an alkaline methylolation followed by an acid condensation and finally the addition of a final amount of urea. The other process, the strongly acid process, consists of four steps, in which the first step involves a strongly acid condensation followed by an alkaline methylolation, a second condensation under a moderately acid pH and finally, methylolation and neutralization under a slight alkaline pH. Two resins were produced using the two above described processes. The molecular weight distribution (MWD) of the resins was monitored off-line by GPC/SEC and the final resins were characterized by GPC/SEC and HPLC. These studies showed that the two resins differ greatly in chemical structure, composition, viscosity, and reactivity. The monitoring of MWD indicated that the first condensation under a strongly acid environment leads to the production of a polymer with a distinctly different chemical structure, therefore increasing the flexibility of polymer synthesis and opening the way to the improvement of end-use properties. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1764-1772, 2012
Subject: Ciências Tecnológicas, Química
Technological sciences, Chemical sciences
Scientific areas: Ciências exactas e naturais::Química
Natural sciences::Chemical sciences
Related Information: info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e Tecnologia/Programa de Financiamento Plurianual de Unidades de I&D/PEst-C/EQB/LA0020/2011/Projeto Estratégico-LA 20 - 2011-2012/LA 20
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Revista Científica Internacional

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