Agricultural proteins as multifunctional additives in ZnO-free synthetic isoprene rubber vulcanizates |
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Authors: | Barbara L DeButts Natasha Chauhan Justin R Barone |
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Affiliation: | 1. Macromolecular Science and Engineering and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia, 24061;2. Department of Chemical Engineering, Virginia Tech, 245 Goodwin Hall, 635 Prices Fork Road, Blacksburg, Virginia, 24061 |
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Abstract: | Corn zein and wheat gliadin protein are compounded into synthetic cis-1,4-polyisoprene rubber (IR) and sulfur-cured in a zinc oxide (ZnO)-free system. The curing kinetics and mechanical and morphological properties are compared to a ZnO-activated or carbon black (CB)-reinforced cure system. The proteins provide reversion resistance and reinforcement to IR at filler loadings as low as 1 part per hundred rubber (phr). The zein-IR composites exhibit higher moduli, better filler–matrix adhesion, and less filler agglomeration/migration than gliadin-IR because zein is more chemically compatible with IR. The gliadin-IR composites have a lower percent set and hysteresis, indicating the formation of an elastic restoring gliadin network. Optimal properties are achieved at 2-phr gliadin and 4-phr zein. At gliadin loading >2 phr and zein loading >4 phr, the protein domain size increases and mechanical properties deteriorate. At equal filler loading, property improvements over CB-IR are observed for one or both proteins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48141. |
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Keywords: | composites mechanical properties proteins rheology rubber |
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