2022 Annual Meeting
Guayule: A Domestic Source of Natural Rubber Ideal for Arid Regions
Guayule (Parthenium argentatum) is a perennial shrub native to the southwestern U.S. and north-central Mexico. Guayule is a member of the Asteraceae plant family (over 20,000 species) and a source of high-quality natural rubber very similar to that from the rubber tree (Hevea brasiliensis). Applications for natural rubber include vehicle tires, pharmacy/medicine, and food handling/packing. Natural Hevea latex rubber contains an allergic protein called pro-hevein; guayule rubber does not contain this protein and thus, can be used by those with a latex allergy. Identifying value-added commercial applications for guayule resin will reduce the environmental impacts and net costs of rubber production, and increase the economic viability of guayule as an industrial crop. Guayule can be grown in arid regions and does not require a high production input (irrigation, fertilizers, etc.). The physical properties of guayule rubber products are strongly affected by the non-rubber constituents (resin) in the plant, so the separation of resin is a crucial step in processing guayule. Here, we describe guayule resin chemical composition, extraction methods used to isolate guayule resin fractions, and applications for these fractions. The characterization of guayule resin showed the presence of fatty acids, mono- and sesquiterpenes, and their oxygenated derivatives. As part of this project, we are testing the toxicity and avoidance efficacy of guayule resin fractions as bio-based repellents for urban pest insects. Using resin chemistry information, a resin biorefinery model is being developed to include the most efficient and scalable separations for each group of compounds. The model focuses on maximizing total economic value of extractable fractions, increasing the scale and robustness of extraction methods, and lowering the operational costs and environmental impacts of extraction.