Polymerization of commercial Mexican sulfur

Abstract

As it is well known, the physical characteristics of sulfur exhibit a wide range of interesting phenomena around 160 degrees C [1]: a) A shear viscosity change of four orders of magnitude over a 25 degrees C interval [2]. b) Changes in density and in sound velocity. c) Its color becomes darker and its refractive index and dielectric permittivity reach a minimum. d) Of special interest, because of its possible industrial applications, is the polymerization process that occurs at around 160 degrees C. Studies made in ultra pure sulfur (99.999%) have shed some light on this phenomenon, but a coherent picture is still missing. The properties of sulfur are strongly affected by impurities and dissolved gases, so that a great deal of care is necessary when performing these experiments. If the purpose is to take advantages of these properties for industrial applications, one must rule out the use of ultra-pure sulfur and think in terms of a simple process with a commercial substance. In this work we shall report some infrared spectroscopy, Raman spectroscopy and X-ray diffraction results obtained in our attempts at the polymerization of commercial Mexican sulfur.