Study of Morphology and Thermal Behavior of Newly Prepared Plasticized Sulfurs

The morphology of plasticized sulfur with styrene (STY) and dicyclopentadiene (DCPD) was studied using scanning electron microscopy, to investigate the influence of type of additive and time on the rate of conversion of β- to α-structure. The results revealed that major part of plasticized sulfur with STY converted to α-phase after 30 days. While the DCPD-plasticized sulfur mostly possessed a β-structure and only a minor part was converted to α-structure with the elapse of time. The thermal behavior of sulfur, molten sulfur, and the plasticized sulfur samples were studied by thermogravimetry (TG) and differential scanning calorimetry (DSC), 522 days after their preparation. The results clearly revealed that, among different samples studied, the DCPD-plasticized sulfur possesses the highest thermal stability. The effect of addition of micro- and nanosilica, as modifiers, on the morphology and thermal behavior of the STY-plasticized sulfur was also studied. It was found that the presence of the above fillers to the matrix of STY-plasticized sulfur not only caused the creation of some cracks in the sample, but also could not block the conversation of β- to α-structure.