Combining agriculture and energy industry waste products to yield recyclable, thermally healable copolymers of elemental sulfur and oleic acid

Abstract

ABSTRACTSulfur and oleic acid, two components of industrial waste/byproducts, were combined in an effort to prepare more sustainable polymeric materials. Zinc oxide was employed to serve the dual role of compatibilizing immiscible sulfur and oleic acid as well as to suppress evolution of toxic H2S gas during reaction at high temperature. The reaction of sulfur, oleic acid, and zinc oxide led to a series of composites, ZOSx (x = wt % sulfur, where x is 8–99). The ZOSx materials ranged from sticky tars to hard solids at room temperature. The ZOSx compositions were assessed by 1H NMR spectrometry, FTIR spectroscopy, and elemental microanalysis. Copolymers ZOS59‐99, were further analyzed for thermal and mechanical properties by thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. Remarkably, even ZOS99, comprising only 1 wt % of zinc oxide/oleic acid (99 wt % S) exhibits at least an eightfold increase in storage modulus compared to sulfur alone. The four solid samples (59–99 wt % S) were thermally healable and readily remeltable with full retention of mechanical durability. These materials represent a valuable proof‐of‐concept for sustainably sourced, recyclable materials from unsaturated fatty acid waste products. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1704–1710