resumo
In this work, two synthesis procedures for the preparation of urea-formaldehyde (UF) resins, based on the alkaline-acid process, are studied in order to better understand the chemical reactions involved. For that purpose, the number of urea loads and the methyolation temperature were varied. The molecular weight distribution of the resins was monitored by gel permeation chromatography/size exclusion chromatography and the unreacted oligomers by high-performance liquid chromatography, during the synthesis processes. Chemical modifications were investigated using quantitative analysis by carbon-13 nuclear magnetic resonance of samples taken during the synthesis. The largest difference identified between the procedures regards the methylene linkages and methylol groups determined by C-13 NMR. With the results of this study, it is possible to optimize the process and the properties of particleboards produced.
palavras-chave
ADHESIVES; CRYSTALLINITY; SPECTROSCOPY; PERFORMANCE; SEPARATION; STRENGTH; FTIR
categoria
Engineering
autores
Goncalves, C; Pereira, J; Paiva, N; Ferra, J; Martins, J; Magalhaes, F; Barros-Timmons, A; Carvalho, L
nossos autores
Ana Margarida Madeira Viegas de Barros Timmons
Professor associado
Carolina Helena Peixoto Gonçalves
Estudante de doutoramentoagradecimentos
Carolina Goncalves thanks ENGIQ - Doctoral Programme in Refining, Petrochemical and Chemical Engineering (PDERPQ); FCT and EuroResinas - Industrias Quimicas for the PhD grant PD/BDE/114352/2016. This work was financially supported by project UID/EQU/00511/2019 - Laboratory for Process Engineering, Environment, Biotechnology and Energy - LEPABE funded by national funds through FCT/MCTES (PIDDAC); the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement and 2GAR project under PT2020.