Autor(es): Nádia T. Paiva ; Ana Henriques ; Paulo Cruz ; João M. Ferra ; Luísa H. Carvalho ; Fernão D. Magalhães
Data: 2012
Identificador Persistente: https://hdl.handle.net/10216/103471
Origem: Repositório Aberto da Universidade do Porto
Assunto(s): Engenharia de materiais, Química; Materials engineering, Chemical sciences; Engenharia de materiais, Química; Engenharia de materiais, Química; Materials engineering, Chemical sciences; Materials engineering, Chemical sciences
Melamine can be incorporated in the synthesis of urea-formaldehyde (UF) resins to improve performance in particleboards (PB), mostly in terms of hydrolysis resistance and formaldehyde emission. In this work, melamine-fortified UF resins were synthesized using a strong acid process. The best step for melamine addition and the effect of the reaction pH on the resin characteristics and performance were evaluated. Results showed that melamine incorporation is more effective when added on the initial acidic stage. The condensation reaction pH has a significant effect on the synthesis process. A pH below 3.0 results on a very fast reaction that is difficult to control. On the other hand, with pH values above 5.0, the condensation reaction becomes excessively slow. PBs panels produced with resins synthesized with a condensation pH between 4.5 and 4.7 showed good overall performance, both in terms of internal bond strength and formaldehyde emissions. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
