Low-Cost and High-Strength Soybean Meal Adhesives Modified by Tannin–Phenol–Formaldehyde Resin

Abstract

Wood adhesive is very important to the quality of wood-based panels in the forest product industry. Researchers are currently focused on developing green and environmentally friendly adhesives using biomass materials. Soybean meal (SM), a cheap and high-protein byproduct from soybean processing, is considered a green biomaterial resource for adhesive production. In this study, SM was modified using urea and sodium hydroxide as denaturants, and two cross-linking agents were prepared to incorporate into the soybean meal adhesive for bonding reactions. Sodium hydroxide added to soybean protein caused structural damage to the protein structure, which allowed the peptide chains to unfold extensively, forming a low-molecular-weight peptide mixture with a good size distribution and exposing numerous active functional groups for cross-linking with the tannin–phenol–formaldehyde resin (TR) and wood. Adding the epoxy resin CA and TR enabled the cross-linking agents to react with the active functional groups on proteins, forming a cross-linked network structure. As a result, the adhesive’s strength, residual rate, and solid content were improved.

In Situ Synthesis of Gold Nanoparticles from Chitin Nanogels and Their Drug Release Response to Stimulation

“…The microscopic morphology of the prepared CNGs@AuNP samples was observed by high-resolution transmission electron microscopy (HRTEM, JEM-2100, Japan) [30,31]. The samples were dispersed and diluted to a suitable magnification with an ultrasonic cell disruptor (ultrasonic cell disrupt, SB-3200D, China).…”

Crosslinking Mechanism of Tannin-Based Adhesives Based on Model Compounds: Copolycondensation of Resorcinol with Dimethylol Urea

“…As a result, the final bonding strength of TF resin is not ideal. Meanwhile, it shows poorer water resistance and higher brittleness than traditional adhesives [18,[27][28][29][30].…”