Location: Commodity Utilization ResearchTitle: Evaluation of adhesion properties of blends of cottonseed protein and anionic water-soluble polymers
Submitted to: Journal of Adhesion Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2018
Publication Date: 1/15/2019
Citation: Cheng, H.N., Wyckoff, W., Dowd, M.K., He, Z. 2019. Evaluation of adhesion properties of blends of cottonseed protein and anionic water-soluble polymers. Journal of Adhesion Science and Technology. 33(1):66-78. https://doi.org/10.1080/01694243.2018.1495404.
Interpretive Summary: The global wood adhesives market is very large, but most of the product formulations include formaldehyde-based resins as the main components. In order to decrease the usage of formaldehyde and petroleum-derived raw materials, there has been a lot of interest in using protein-based wood adhesives as more eco-friendly and sustainable alternatives. However, the adhesive strength, water resistance, and cost of the proteins remain to be the main issues that prevent their wide acceptance. In our previous work, we have found cottonseed protein to be a promising wood adhesive material. In this work, we found a number of polymeric additives that could further improve the benefit/cost ratio of cottonseed protein. Thus, we investigated 12 different polymers and found most of them to exhibit enhanced dry adhesive strength and hot water resistance relative to cottonseed protein by itself. In particular, carboxymethyl cellulose and low methoxy pectin imparted 50% or higher dry adhesive strength to cottonseed protein and about 30% improvement to hot water resistance. The improved performance should make cottonseed protein more competitive in wood adhesive formulations.
Technical Abstract: There is increasing interest in agro-based, biodegradable and eco-friendly wood adhesives as partial replacements for petroleum-based adhesives. In this work we studied the adhesion of cottonseed protein isolate (CPI) as blends with several anionic water-soluble polymers. In general, the adhesive strength of CPI was found to increase with the addition of an anionic polymer up to a certain level and then decrease with further polymer addition. However, different types of anionic polymers showed different enhancements. Anionic vinyl polymers that we studied included poly(acrylate), poly(acrylate-co-acrylamide), poly(vinyl sulfate), poly(vinyl sulfonate), and poly(vinyl phosphonate). The best result among them was observed for the blend of CPI/poly(vinyl sulfate) with about 30% improved dry strength over CPI alone. Anionic polysaccharides that we studied included three types of carrageenan, carboxymethyl cellulose (CMC), low-methoxy pectin, alginate, and chondroitin sulfate. The best results were obtained for CPI/CMC and CPI/pectin blends with improvements in dry adhesive strength of 66% and 50%, respectively, over CPI. The CPI/CMC and CPI/pectin blends also showed improved hot water resistance over CPI. These findings suggested that the CPI/anionic polymer blends might be promising materials to be used in wood adhesive formulations.