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Study of influence of synthesis conditions on properties of melamine–urea formaldehyde resins

2012; Taylor & Francis; Volume: 3; Issue: 1 Linguagem: Inglês

10.1179/2042645312y.0000000009

2042-6453

Nádia Paiva, João Pereira, João Ferra, Paulo J. S. Cruz, Luísa Carvalho, Fernão D. Magalhães,

Lignin and Wood Chemistry

The aim of this work is to assess the differences in the polymeric structure and performance of melamine–urea formaldehyde (MUF) resins, when changing relevant synthesis variables: formaldehyde/amine groups [F/(NH2)2] molar ratio (both in the methylolation and the condensation steps) and the feedrate of urea during the condensation step. This synthesis process differs from the traditional alkaline acid process, since the F/(NH2)2 molar ratio is different for the methylolation and condensation steps. It was found that the F/(NH2)2 molar ratio and urea feedrate in the condensation step are the most influential variables on the product characteristics. A relationship was established between polymeric structure of the resin and the physicomechanical properties, as well as the levels of formaldehyde. A resin formulation was obtained that exhibits a formaldehyde content, evaluated both by perforator and desiccator methods, within the Japanese F**** requirements. This resin presents an overall performance better than the one obtained by two representative commercial resins.