Soy meal adhesive with high strength and water resistance via carboxymethylated wood fiber-induced crosslinking

• DOI: 10.1007/s10570-021-03732-x
• Publication Date: 2021-02-19T23:58:10Z
• Authors: Huiwen Pang; Yuyang Wang; Zhiwei Chang; Changlei Xia; Chunrui Han; Hongguang Liu; Jianzhang Li; Shifeng Zhang; Liping Cai; Zhenhua Huang
• Keywords: Water resistance

Soy meal-based wood adhesive has received much interest for its environmentally friendly properties, as it is thought to provide an effective alternative to conventional formaldehyde-based wood adhesives. However, the abundant hydrophilic groups and weak internal structure result in poor water resistance and low bonding strength of soy meal-based wood adhesives. In this study, bio-based carboxymethylated wood fibers (CMWFs) were used to develop a high-performance soy meal-based adhesive. Wood fibers (WFs) were pre-treated via carboxymethylation to endow WFs with abundant carboxyl groups and facilitate their dispersion in soy protein matrix. CMWFs containing abundant carboxyl groups served as a multiple “crosslinking core” and effectively cross-linked with soy protein side-chain, resulting in the construction of a stable adhesive system. The modified soy meal-based adhesive exhibited excellent bonding strength and water resistance. In particular, tension tests indicated that the water-resistant bonding strength of the adhesive modified with CMWFs reached 1.69 MPa, which was 160% higher compared with the unmodified adhesive; the wood failure percentage of the plywood bonded by CMWF-modified soy meal-based adhesive was as high as 100%. Moisture uptake and residual rate tests indicated that high water resistance of the adhesive was achieved. This design provides a facile and sustainable strategy for developing high-performance soy meal-based adhesives.