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

• Type: Article in International Scientific Journal
• Date: 2018

Authors

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

Journal

Title: Materials

Vol. 11 No. 6

Pages: 1-11

ISSN: 1996-1944

Publisher: MDPI

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 4 Citations

INSPEC

Associated Projects

2GAR - 2GAR - Resinas Amino de segunda Geração

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

Other information

Authenticus ID: 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).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11