Cottonseed used to be among the most useless of agricultural byproducts, until the industrial age figured out what it could do with cottonseed oil. Gradually, more and more uses were found for the oil, and now it and corn oil are being studied as sources of biobased polyols for making polyurethane (PUR), as described in a recently published paper. (This paper is one of the articles in the new special issue of the Journal of Renewable Materials, which contains a selection of papers presented at the 5th International Conference on Biobased and Biodegradable Polymers (BIOPOL-2015), held in Spain last October.)
A 19th-century stereoscopic image of “a pyramid of cotton seed” in Florida (image from commons.wikimedia.org).
Various vegetable oils (VOs) and natural oil byproducts have been turned into polyols for PUR (see, for example, the April 13 JRM Blog posting here). For cottonseed and corn oils, “the fatty acid profiles of both VOs provide them the potential as raw materials for the replacement of petroleum-based building blocks and monomers,” note the new JRM paper’s authors, three of which are based in Mexico. “In addition, corn and cotton crops are a highly social culture in Mexico, generating direct and indirect labor, as they are able to produce a high number of original products and by-products from their manufacturing…”
The researchers converted the two oils into polyols and reacted them with 4,4′-methylene diphenyl diisocyanate (MDI) and hexamethylene diisocyanate (HDI) to make PUR. FTIR spectroscopy and thermal analysis were performed to compare the different polyols and the resulting PURs. Thermal analysis (DSC), for instance, revealed that the choice of isocyanate influences glass transition temperature, making some PURs more rigid than others at or above room temperature.
Overall, as the authors conclude, “Polyurethanes synthesized by using both types of biobased polyols and HDI and MDI showed homogeneous and nonporous morphologies with high thermal stability.”
Again, for readers who missed attending BIOPOL-2015: Volume 4, number 3 of the JRM, filled with papers from the conference, will soon be released; check for the new papers here.
You can also follow the “J Renewable Materials Blog” via Twitter at @scrivpub.
Also online from the Journal of Renewable Materials: new “fast track” articles. You can sample an issue of the JRM, or acquire any article as an individual download. This blog’s moderator and editor is Mike Tolinski, author of Plastics and Sustainability.