Copolymerization of UF Resins with Dimethylurea for Improving Storage Stability without Impairing Adhesive Performance

• Tipo: Artigo em Revista Científica Internacional
• Data: 2018

Autores

Pedro Pereira (Autor) Outra; João Pereira (Autor) Outra; Nádia. T. Paiva (Autor) Outra; João. M. Ferra (Autor) Outra; Jorge M. Martins (Autor) Outra; Luísa H. Carvalho (Autor) FEUP; Fernão D. Magalhães (Autor) FEUP

Revista

Título: Materials

Vol. 11 Nº 6

Páginas: 1-11

ISSN: 1996-1944

Editora: MDPI

Indexação

ISI Web of Knowledge - 5 Citações

Scopus - 5 Citações

INSPEC

Projetos Associados

2GAR - 2GAR - Resinas Amino de segunda Geração

LEPABE - Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia

Outras Informações

ID Authenticus: P-00P-0JV

DOI: 10.3390/ma11061032

Abstract (EN): Urea-formaldehyde (UF) resins are the most used resins in the wood industry due to high reactivity and low price. However, their reduced stability during storage is a drawback, imposing strict limits in terms of allowable shipping distances and storage times. This instability, manifested by viscosity increase that renders the resin unusable, occurs due to the progress of condensation reactions between the polymeric species present in the liquid medium. In order to achieve a stable resin formulation, dimethylurea (DMeU) was selected for being less reactive than urea. Dimethylurea is shown to co-polymerize with the UF polymer during the acidic synthesis condensation step. However, during storage it behaves like an end group blocker, due to its lower reactivity at basic pH. By adding 1.25% DMeU, it was possible to obtain a formulation that remained with stable viscosity during two-month storage at 40 degrees C. The reference UF resin remained stable only for eight days in these conditions. Wood particleboards produced with modified resins showed internal bond strengths of about 0.5 Nmm(-2), similar to the fresh reference UF resin, even when the resins were used after the two-month storage period. Formaldehyde content values were below the limit for E1 class, 8 mg/100 g oven dry board (EN 13986).

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11