Characterization of synthesized poly(aryldisulfide) through interfacial polymerization using phase-transfer catalyst

Fabrication and evaluation of novel sulfur/epoxy resin composites

In recent years, and with the progress of oil and natural gas purification processes, it has been noticed that huge quantities of sulfur are produced with millions of tons as byproducts, which is considered a dangerous substance that may threaten the safety and health of the environment. So, this study aims to maximize elemental sulfur benefits in construction applications, especially in the coating sector. In this study, sulfur has been modified to be used with epoxy as a high-performance coating material. Firstly, sulfur was modified with linseed oil at 160 °C. The modified sulfur was chemically characterized by using FTIR and XRD. After that, epoxy was then partially replaced by polymeric sulfur with different weight percentages starting from 10 to 40%. Then, the hardener was added to form cured sulfur/epoxy composites. Different techniques were used to examine the morphology of the prepared composites such as AFM, polarizing microscope, and SEM. The thermal study was also conducted by TGA. In addition, the mechanical properties were comprehensively studied including Young’s modulus, toughness, tensile strength, hardness, and adhesion. The results approved that Young’s modulus, toughness, tensile strength, hardness, and adhesion of the PC4 composite have been improved by 54%, 87%, 15%, 40%, and 33%, respectively. Moreover, the prepared composites give high thermal stability than virgin epoxy. The overall results approved that the epoxy can be partially replaced by modified sulfur with high weight ratios reached to 40%.

Enhanced thermal properties of poly(ethylene tetrasulfide) via expanded graphite incorporation by in situ polymerization method

In this study, a novel poly(ethylene tetrasulfide) (PETS)/expanded graphite (EG) nanocomposite with 40°C improvement in melting point is prepared via in situ polymerization technique. The morphology, chemical characteristics and the structural behavior of nanocomposites are characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and x-ray diffraction (XRD) techniques, respectively. XRD observations show about 0.1 nm increase in d-spacing of PETS crystals in the presence of 2 wt% EG in nanocomposite. This behavior could be related to the intercalation of polysulfide macromolecules in the interlayer structure of EG sheets. Furthermore, the thermal properties of nanocomposites are investigated using differential scanning calorimetry and thermogravimetric analysis techniques. The thermal degradation temperature of nanocomposite containing 2 wt% graphite shows an improvement of about 10°C compared to unfilled polysulfide. Moreover, the chemical resistance of nanocomposites in different common solvents increases in the presence of EG, which could be accounted as a clear proof of interconnections for EG and macromolecular structure of the polymer.