|KOSTYAL, DAVID - Akron Rubber Development Laboratory|
|CORNISH, KATRINA - The Ohio State University|
Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2015
Publication Date: 3/17/2015
Citation: Mcmahan, C.M., Kostyal, D., Lhamo, D., Cornish, K. 2015. Protein influences on guayule and Hevea natural rubber sol and gel. Journal of Applied Polymer Science. 132, 42051, DOI: 10.1002/app.42051.
Interpretive Summary: Widespread cultivation of guayule (Parthenium argentatum) in the southwestern US will require high demand for guayule natural rubber. The fit of this material for use in specific applications, such as medical products, consumer goods, or tires, depends on the physical and chemical properties of guayule rubber, which can be different from those of the incumbent Hevea (rubber tree) natural rubber. In this study we demonstrate two important differences: 1) Proteins from Hevea and guayule do not cross-react, demonstrating that guayule rubber is safe for people with Type I latex allergy, and that guayule rubber contains low levels of its unique set of proteins. 2) The material stiffness of natural rubber, measured as bulk viscosity, determines it’s processability in manufacturing. For natural rubbers, manufacturing processability depends on rubber molecule size (length), the amount of extractable (oils and resins) and the amount of insoluble (cross linked gel) present. All of these features are controlled by the biology of the plants, the environment in which they are cultivated, and the processes used to extract the rubber.
Technical Abstract: Guayule (Parthenium argentatum) is under cultivation in the southwestern United States as an alternative source of natural rubber free from proteins that cause Type I latex allergies. However, since guayule lacks the protein-polymer interactions present in Hevea latex, its physical and chemical properties may differ. The solvent-soluble (Sol) and insoluble (Gel) fractions from guayule and Hevea natural rubbers were isolated through a solubilization/centrifugation deproteinization process. Protein could be reduced or removed by centrifugation, or concentrated in the gel fraction for both Hevea and guayule rubber. Separation of the sol fraction of Hevea rubber reduced the overall protein level, in some cases to below detection limits, without impacting rubber thermo-oxidative stability. Notably, no detectable cross reactions took place between guayule protein antibodies and Hevea-based materials, nor vice versa.