Production of yellow poplar interior plywood with cottonseed-based protein adhesives

Authors: SHMULSKY, RUBIN - Mississippi State University; Dowd, Michael; LOPES, DERCILIO - Mississippi State University; MILLER, GEORGE - Mississippi State University; ENTSMINGER, EDWARD - Mississippi State University

Submitted to: Wood and Fiber Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2021
Publication Date: 8/11/2021
Citation: Shmulsky, R., Dowd, M.K., Lopes, D.J.V., Miller Jr., G.D., Entsminger, E.D. 2021. Production of yellow poplar interior plywood with cottonseed-based protein adhesives. Wood and Fiber Science. 53(3):206-215. https://doi.org/10.22382/wfs-2021-20.
DOI: https://doi.org/10.22382/wfs-2021-20

Interpretive Summary: In this work, cottonseed meals were used to formulate wood adhesives and were tested for their ability to make poplar plywood panels. Testing of the prepared panels found that the panels formed from the cottonseed-based adhesives had comparable adhesive strength to panels made from a control soybean formulation. Additionally, the cottonseed based-panels exhibited sufficient water resistant to pass standard water resistance tests for interior grade plywoods. The results indicate that cottonseed proteins can compete with soybean proteins for some wood adhesive applications. The work should be of interest to researchers developing formaldehyde free bio-based wood adhesives and members of the wood products industry.

Technical Abstract: Defatted cottonseed (CS) and water-washed CS meals were prepared from glandless CS and were used in adhesive formulations to produce 3-ply yellow poplar plywood panels. Adhesive resins were prepared from each protein meal with sodium bisulfite and one of two polyamido-amine-epichlorohydrin wet strength agents, and the plywood panels were produced by hot pressing. Shear strength and water resistance were determined by ASTM and ANSI/HPVA methods and were compared to the properties of plywood panels made with an adhesive formulated from a commercial soybean meal. All three protein meals resulted in panels with comparable shear strengths. The combinations of the two CS preparations and the two wet strength agents also produced panels with acceptable wet resistant properties, whereas the soybean meal only produced acceptable panels with one of the wet strength agents. As the two CS meal products resulted in plywood panels with comparable properties, there appears to be no benefit for including the additional water-washing step that was used to increase the meal’s protein level. In contrast with a recent literature report that suggests that the addition of alkali to elevate the formulation pH was necessary with CS meal, suitable panels were prepared herein without the addition of the base. The difference may have been due to the slightly higher pressing temperature and longer press times used in this work compared to earlier results. The CS meals showed promise as formaldehyde-free hardwood-plywood wood-based adhesives for interior applications.