67th Annual Meeting of the APS Division of Fluid Dynamics (November 23, 2014 — November 25, 2014)

V0090: Shades of Sulfur

Authors

• Gabriela Bran Anleu, University of California, Los Angeles
• Hamarz Aryafar, Univerity of California, Los Angeles
• Richard Wirz, Univerity of California, Los Angeles
• Pirouz Kavehpour, University of California, Los Angeles

DOI: https://doi.org/10.1103/APS.DFD.2014.GFM.V0090

Sulfur has unusual physical and chemical properties. It has a great variety of possible molecular structures and versatility by which it can react with inorganic and organic substances. In the study of material compatibility in sulfur systems, sulfur propensity to catenation and interconversion of its allotropic forms need to be well understood. Sulfur can exist in a large number of different molecular forms. The most stable form of sulfur is S8, and it is the predominant form at ambient temperature. Smaller sulfur molecules (S2, S3, and S4) are highly reactive. The most important modifications are Sα, Sλ, Sβ, Sμ, and Sπ. The change in molecular structure results in a change of color, viscosity, and solubility. The modifications of sulfur are strictly linked with changes in temperature. The stable solid modification of sulfur is yellow Sα. Sulfur melts at 112.8 ºC, and the yellow liquid sulfur contains a combination of Sα and Sλ. As temperature increases, the color changes to orange and then to red due to the presence of Sλ, Sμ, and Sπ. At 160ºC, the molten sulfur changes color to a dark brown solution and the viscosity increases drastically. A drastic change in viscosity is observed at temperatures between 150 ºC and 250 ºC.