Preparation of water-resistant soybean meal-based adhesives with waste paper cellulose via NaOH/urea pretreatment and oxidation

摘要

Fiber agglomeration and poor interfacial combination with the matrix restrict the performance of composites. Herein, soybean meal-based adhesives were fabricated via the addition of dialdehyde cellulose (DAC) obtained from waste paper dissolved in an alkali-urea system and oxidized with sodium periodate. Due to the dissolution by the alkali-urea system, DAC dispersed well in the solution and did not aggregate in the adhesive matrix. Because of the oxidation treatment, DAC was crosslinked with the adhesive matrix via a Schiff base reaction. Meanwhile, hydrogen bonds were formed at the interface between the DAC and the adhesive matrix. Plywood with the SM/DAC/PTGE adhesive reached its highest wet bonding strength of 1.27 MPa (4 wt% DAC addition), a 95% increase compared to that with the unmodified SM/PTGE adhesive. Fine DAC-to-SM interfacial bonding and a dense crosslinking network were constructed in the SM/DAC/PTGE adhesive systems. The cycle of reuse for the alkali-urea system in the experiments demonstrated that the preparation method of the cellulose solution was scalable and sustainable.