Cottonseed protein-based wood adhesive reinforced with nanocellulose

Authors: CHENG, HUAI; KILGORE, KAYLIN; Ford, Catrina; Fortier, Chanel; DOWD, MICHAEL; He, Zhongqi

Submitted to: Journal of Adhesion Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2019
Publication Date: 5/9/2019
Citation: Cheng, H.N., Kilgore, K., Ford, C., Fortier, C., Dowd, M.K., He, Z. 2019. Cottonseed protein-based wood adhesive reinforced with nanocellulose. Journal of Adhesion Science and Technology. 33(12):1357-1368. https://doi.org/10.1080/01694243.2019.1596650.
DOI: https://doi.org/10.1080/01694243.2019.1596650

Interpretive Summary: Since cotton is a major agricultural product in the southern United States, we have done a fair amount of work on the use of cottonseed protein as a wood adhesive. In view of the current interest in nanotechnology, a question may be asked if the addition of nanocellulose to cottonseed protein would improve its performance as a wood adhesive. It was shown in this work that indeed both types of nanocellulose (cellulose nanofibers and cellulose nanocrystals) could improve the adhesive performance of cottonseed protein at optimal additive levels. Cellulose nanofibers are optimal at about 2% additive level, giving approximately 25% improvement in dry adhesive strength over the cottonseed protein by itself. For cellulose nanocrystals, the optimal level was about 10%, where the adhesive performance improved by about 15% over the protein by itself. About the same percent improvements were also found for soy protein. These findings suggest that nanocellulose may be a useful additive for protein adhesive formulations.

Technical Abstract: Although protein-based adhesives are eco-friendly, sustainable, and biodegradable, continued improvement in their adhesive performance is desirable. In this work, the effect of adding nanocellulose particles to cottonseed protein-based wood adhesives was studied. Cellulose nanofibers (CNF) were found to be most beneficial at about a 2% additive level, giving 22% improvement in dry adhesive strength over the cottonseed protein control. Cellulose nanocrystals (CNC) were optimal at about 10% additive level, giving 16% strength improvement relative to cottonseed protein alone. The hot water resistance of cottonseed protein isolate was also improved with CNF addition, but not with CNC addition. For comparison, soy protein isolate was also studied and showed about the same relative dry strength improvements with nanocellulose addition, but improvement of hot water resistance was less apparent. Infrared and thermogravimetric analysis suggested that the protein and the nanocellulose were interacting with each other. Thus, CNF may be a useful additive to cottonseed protein formulations used as wood adhesives.