Utilize este identificador para referenciar este registo:
https://hdl.handle.net/10216/103475
Autor(es): | João M. M. Ferra Ana Henriques Adélio M. Mendes Mário Rui N. Costa Luísa H. Carvalho Fernão D. Magalhães |
Título: | Comparison of UF synthesis by alkaline-acid and strongly acid processes |
Data de publicação: | 2012 |
Resumo: | 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 |
Assunto: | Ciências Tecnológicas, Química Technological sciences, Chemical sciences |
Áreas do conhecimento: | Ciências exactas e naturais::Química Natural sciences::Chemical sciences |
URI: | https://hdl.handle.net/10216/103475 |
Informação Relacionada: | info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e a Tecnologia/Programa de Financiamento Plurianual de Unidades de I&D/PEst-C/EQB/LA0020/2011/Projeto Estratégico-LA 20 - 2011-2012/LA 20 |
Tipo de Documento: | Artigo em Revista Científica Internacional |
Condições de Acesso: | restrictedAccess |
Aparece nas coleções: | FEUP - Artigo em Revista Científica Internacional |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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62255.pdf Restricted Access | Artigo original publicado | 721.77 kB | Adobe PDF | Request a copy from the Author(s) |
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