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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Bioproducts Research » Research » Publications at this Location » Publication #335297

Research Project: Domestic Production of Natural Rubber and Industrial Seed Oils

Location: Bioproducts Research

Title: Effect of non-rubber constituents on Guayule and Hevea rubber intrinsic properties

item MONADJEMI, SHIRIN - The Ohio State University
item McMahan, Colleen
item CORNISH, KATRINA - The Ohio State University

Submitted to: Journal of Research Updates in Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2016
Publication Date: 8/11/2016
Citation: Monadjemi, S., McMahan, C.M., Cornish, K. 2016. Effect of non-rubber constituents on Guayule and Hevea rubber intrinsic properties. Journal of Research Updates in Polymer Science. 5(5):87-96. doi: 10.6000/1929-5995.2016.05.03.1.

Interpretive Summary: Parthenium argentatum (guayule) has emerged on the market as a potential commercial source of high quality natural rubber from US agriculture. However, compared to the incumbent Hevea natural rubber, guayule rubber exhibits low green strength and low strain-induced crystallizability. This study documents the plasticizing (softening) effect of organic resins and neutral lipids present in guayule natural rubber. Removal of the resins increased the material strength. Removal of residual rubber particle membrane components also had beneficial effects. Post-harvest modification of guayule rubber is one approach to expanding the uses of the material in industrial markets.

Technical Abstract: To meet the increasing demand for natural rubber (NR), currently sourced from the tropical rubber tree Hevea brasiliensis, and address price volatility and steadily increasing labor costs, alternate rubber-producing species are in commercial development. One of these, guayule (Parthenium argentatum), has emerged on the market as a commercial source of high quality rubber. Non-rubber constituents play an important role in the physical properties of NR products. The intrinsic composition of the two NR materials differs and these differences may be a principal cause of the performance differences between them. We have compared the effect of non-rubber constituents, such as protein, lipids, resin and rubber particle membranes. Firstly, a film casting method was developed to obtain rubber films with a uniform thickness. Secondly, the glass transition temperature of different rubbers was determined by dynamic mechanical analysis, and tensile properties were tested for uncompounded materials. Guayule natural rubber (GNR), from which most of the membranes were removed while in latex form (MRGNR) was found to have higher intrinsic strength than GNR or gel-free NR (FNR). An acetone extraction was performed to quantify the resin and free lipids in the rubber samples.