Hydroxymethyl furfural-modified urea–formaldehyde resin: synthesis and properties

Abstract

Considering the importance of urea–formaldehyde (UF) resins in the wood industry, this work reports on a new bio-based modification of UF resins. The use of 5-hydroxymethyl furfural (HMF) is motivated by the current concerns about the effects of formaldehyde on human health. UF and urea–HMF–formaldehyde (UHF) resins were synthesized by an alkaline-acid method and characterized by FTIR, thermogravimetric analysis, and differential scanning calorimetry. The UHF, as a newly modified polymeric resin, was thermally characterized, and it was found that its thermo-stability and char yield was improved. In order to investigate the performance of the UHF, the preparation of particleboards with the UHF as adhesive, as well as its film formation ability have been studied. The UHF films formed on wood panels were uniform without any crack. Film formation ability of the UHF resin was improved due to the presence of more hydroxyl groups as well as furan rings of the HMF moieties resulting in more activated groups to be bonded by wood. Furthermore, formaldehyde release of the particleboards bonded by UHF was significantly lower than that of which bonded by the UF resin. Lab particleboards using the UHF resins showed higher modulus of rupture, modulus of elasticity, and internal bond compared to boards with UF resins, as well as lower water absorption and thickness swelling. Based on these results UHF resin can be considered as a possible candidate as adhesive for wood and wood based panels.