- Plasticized sulphur is produced when melted sulphur is reacted with selected hydrocarbons to produce polysulfides. These polysulfides help retain a 'polymeric' nature of the plasticized sulfur which is similar to asphalt cement. Plasticized sulphur was developed as a replacement for asphalt cement. The first generation of plasticized sulphurs developed by Southwest Research Institute (SWRI) were given the trade name Sulphlex. This paper discusses the development of a second generation of Sulphlex binders with improved structural properties. Second generation Sulphlexes were developed with improved cold climate fatigue resistance. This paper discusses the exhaustive research and development effort on these plasticized sulfur paving mixtures.