Sulfur polymer composites as controlled-release fertilisers

Abstract

A controlled-release fertiliser was prepared by the inverse vulcanisation of canola oil in the presence of nitrogen, phosphorous and potassium nutrients.

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

“…One reason for this may be that the molten sulfur and alkyl carboxylic acids are largely immiscible because of the incompatibility of the very polar carboxylic acid moiety and the hydrophobic sulfur phase. Immiscibility of sulfur and organics is a familiar problem in the rubber vulcanization literature, as sulfur and rubber are likewise relatively immiscible . To overcome this challenge and produce homogeneous vulcanized rubber products, early vulcanization processes used stearic acid, a saturated fatty acid, and ZnO as compatibilizing agents.…”

“…OA was selected as the FFA for inverse vulcanization in the current study because it is the major unsaturated fatty acid in animal and plant fats/oils targeted for valorization. Chalker has already established that elemental sulfur can react with triglycerides, which are esterified fatty acids. Initial efforts to employ FFAs as the olefinic component for inverse vulcanization, however, does not appear to have been undertaken.…”

“…Inverse vulcanization (Scheme ) has emerged as an intriguing approach to valorizing agricultural waste through the combination of sulfur with plant‐derived olefins . The sulfur used in the inverse vulcanization process is itself a waste product from desulfurization of fossil fuels, so when sustainably sourced waste product olefins are employed the materials achieved can be comprised entirely of waste products.…”

Valorization of Lignin as a Sustainable Component of Structural Materials and Composites: Advances from 2011 to 2019

“…Although elemental sulfur itself is quite brittle, durable materials can be obtained for the copolymers comprising up to 90 wt.% sulfur [51][52][53][54]. These efforts have employed a wide range of starting materials including cellulose, lignin, amino acids, terpenoids, algae acids, polystyrene derivatives, and other olefins [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70]. More recently, radical-induced aryl halide/sulfur polymerization (RASP) proved similarly effective for preparation of high sulfur-content materials (HSMs) but employing aryl halides in place of the olefins required for inverse vulcanization.…”

Crosslinker Copolymerization for Property Control in Inverse Vulcanization

“…Despite ac rosslinked structure, the reversibility of sulfur-sulfur bonds allows recycling [9] and repair. [6] Other reported applicationsi nclude LiS batteries, [4,10,11] water purification, [12][13][14][15][16][17] the stabilizationo fm etal nanoparticles and quantum dots, [18][19][20][21] controlled-release of fertilizers, [22] and antimicrobial materials, [23] and there are doubtless many more applicationsy et to be discovered. Fully realizing the potential of sulfur polymers for these applicationsw ill depend on the physicalp roperties of the polymers themselves.…”