Enhancing the performance of low molar ratio urea-formaldehyde resin adhesives via in-situ modification with intercalated nanoclay

Low molar ratio urea-formaldehyde (UF) resin adhesives are primarily used for the reduction of formaldehyde emission (FE) from wood-based composites, at the expense of poor reactivity and adhesion. This study aimed to enhance the performance of low molar ratio UF resins via in-situ modification, via the addition of octadecylamine (ODA)-modified bentonite (ODA-BNT) nanoclay. The molecular weights, curing behavior, chemical groups, and crystallinity of modified UF resins with different levels of ODA-BNT were characterized by gel permeation chromatography, differential scanning calorimetry, Fourier-transform infrared spectroscopy, and X-ray diffraction (XRD). The ODA-BNT/UF resins showed better reactivity and lower activation energy compared with neat resins. The XRD results clearly showed that ODA-BNT in modified UF resins had been intercalated. A 5% ODA-BNT addition resulted in a decrease in the crystallinity of the modified UF resins, leading to better adhesion strength and lower FE compared with neat UF resins. These results suggest that intercalation of ODA-BNT in low molar ratio UF resins improve their cohesion through the formation of a larger branched network in their cured state.

Automated summary

This study aimed to enhance the performance of low molar ratio UF resins by in-situ modification with ODA-BNT nanoclay. The modified UF resins showed better reactivity and lower activation energy, resulting in improved adhesion strength and lower formaldehyde emission compared to neat resins. The intercalation of ODA-BNT in low molar ratio UF resins improved their cohesion by forming a larger branched network in their cured state.