Influence of a hydrocarbon side chain on the performance of Physaria fendleri-Castor oil polyurethane packaging adhesives

Authors: IVEY, ALEXANDRA - Iowa State University; TALBERT, JOEY - Iowa State University; Evangelista, Roque; VORST, KEITH - Iowa State University; CURTZWILER, GREG - Iowa State University

Submitted to: Cleaner Engineering and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2021
Publication Date: 7/16/2021
Citation: Ivey, A., Talbert, J., Evangelista, R.L., Vorst, K., Curtzwiler, G. 2021. Influence of a hydrocarbon side chain on the performance of Physaria fendleri-Castor oil polyurethane packaging adhesives. Cleaner Engineering and Technology. 4. Article 100216. https://doi.org/10.1016/j.clet.2021.100216.
DOI: https://doi.org/10.1016/j.clet.2021.100216

Interpretive Summary: This research evaluated the use of lesquerella oil, obtained from domestically grown mustard plant, as an alternative to imported castor oil used in producing bio-based and environmentally friendly adhesive for food packaging application. This new application is in addition to other potential uses of lesquerella oil in the manufacture of plastics, sealants and coatings, lubricants, and other fine chemicals. Expanding the use of renewable material will reduce our dependence on petroleum-derived products. In addition, creating more uses of lesquerella oil will reduce our demand for imported castor oil and, at the same time, enhance our rural economies.

Technical Abstract: Polyurethanes (PU) are an important class of materials used in various applications across industries. With increased global interest in sustainable and environmentally benign packaging, there is high demand to replace traditional petroleum-based materials with renewable, bio-derived sources. This research developed PU adhesives for multilayer flexible food packaging using Physaria fendleri oil (formerly Lesquerella fendleri) and Ricinus communis (Castor oil), each possessing naturally occurring hydroxyl functional groups. Physaria oil has, on average, hydroxyl functionality on two of the three fatty acids compared to all three for Castor oil; therefore systematically varying the concentration of each oil and maintaining a constant crosslink density for each adhesive facilitates an understanding of the effect of Physaria oil’s unreacted hydrocarbon sidechain on physical properties in biobased adhesives. The results of this study determined that the peel resistance of polyethylene and polyethylene terephthalate substrates adhered with adhesives containing varying amounts of Physaria and castor oils possessed average peel strengths of 6–8 N relatively independent of composition. Furthermore, the glass transition temperatures were measured to be within the range of -25 to -44 deg C with higher concentrations of the hydrocarbon sidechain resulting in lower Tgs. These physical properties indicate their use in multilayer food packaging adhesive applications where isocyanate PU adhesives are still commonplace. Understanding the PU adhesive network structure-property relationships will help develop the next generation of bio-derived PU adhesives with additional sources of renewable feedstocks for food packaging applications.