Polymeric Sulfur Research Articles

Water permeability and rapid self-healing of sustainable sulfur composites using superabsorbent polymer and binary cement

This study investigated the rapid self-sealing of modified sulfur polymer composites incorporating superabsorbent polymer (SAP) and binary cement. The SAP was employed as a primary remedy for the rapid self-sealing in less than 30 min. The binary cement was used as a secondary self-healing element, and was composed of calcium sulfoaluminate (CSA) expansive agent and Portland cement. The mixture cases were prepared and tested varying the proportions of the components of binary cement, depending on the presence of SAP. Water permeability tests were conducted on through-crack samples to evaluate their rapid self-sealing performances under water penetration. Nondestructive tests including elastic wave transmission and optical microscopy were carried out to assess the effectiveness of SAP and binary cement on the rapid self-healing. The test results revealed that the presence of SAP dramatically accelerated the rapid self-sealing performance. The SAP particles quickly swelled up by absorbing water, and sealed and bridged between the two crack faces, which likely assisted the nucleation and growth of hydrated products around them. In addition, an increasing ratio of CSA expansive agent in the binary cement led to the better rapid self-sealing.

Multiple sulfur isotope fractionation in hydrothermal systems in the presence of radical ions and molecular sulfur

This study is aimed to evaluate the role played by the sulfur radical ions (S3− and S2−) and molecular sulfur (S0) on sulfur isotope fractionation and to investigate if these species may leave an isotope fingerprint in hydrothermal systems. For this purpose, we combined (i) experiments using a hydrothermal reactor with aqueous S3−(S2−)-S0-sulfate-sulfide fluids and pyrite across a wide range of temperatures (300–450 °C), pressures (300–800 bars), fluid acidity (4 < pH < 8) and with elevated total sulfur concentrations (0.1–1.0 mol/kg fluid) favorable for formation of those polymeric sulfur species, (ii) precise quadruple S isotope analyses of the different S-bearing aqueous species in sampled fluids and in-situ precipitated pyrite, and (iii) thermodynamic modeling of sulfur aqueous speciation and solubility. Our results quantitatively confirm both equilibrium and kinetic SO4-H2S and pyrite-H2S mass dependent fractionation (MDF) factors previously established using extensive experimental and natural data from more dilute fluids in which polymeric sulfur species are negligible. MDF signatures of S0 measured in the sampled fluids of this study reveal different S0-forming pathways such as (i) breakdown on cooling of S3− (and S2−) and other chain-like S0 polymers only stable at high temperature and being isotopically identical to H2S; (ii) cyclooctasulfur (S80, liquid or solid) precipitating by recombination of sulfate and sulfide and/or by exchange with polysulfide dianions (Sn2−) on cooling and being slightly 34S-enriched compared to H2S (by ∼2‰ of δ34S); and iii) a different type of S0 resulting from thiosulfate irreversible breakdown and being highly 34S-depleted (by ∼12‰) relative to H2S. Our data do not show any significant mass independent fractionation (MIF) of 33S and 36S, with Δ33S and Δ36S values of any S aqueous species and pyrite being within ±0.1‰ and ±1.0‰, respectively. Therefore, under the investigated experimental conditions, the radical S3− ion is unlikely to generate significant MIF in the hydrothermal fluid phase and in pyrite and native sulfur precipitated therefrom. Our study supports the existing interpretations of small Δ33S and Δ36S variations between sulfide/sulfate-bearing fluid and pyrite as MDF in terms of reaction kinetics, different reaction pathways, and mass conservation effects such as mixing of S reservoirs or Rayleigh distillation. Our data extend, across a wider range of sulfur concentration and chemical speciation, the existing multiple S isotopes models that exploit such variations as a complement to the traditional δ34S tracer to monitor the approach to equilibrium and evolution of hydrothermal fluids.

Radiation induced strength enhancement of sulfur polymer concrete composites based on waste and residue fillers

The behavior and properties of sulfur polymer concrete composites (SPC) based on mineral fillers (industrial waste and residues) were investigated towards potential application under high radiation exposure conditions. The composites were irradiated in a dose range up to 1.5 MGy using Co-60 gamma source. The test specimens were subjected to compressive tests, SEM analysis, capillary water absorption tests, XRD, FTIR and DSC analysis. The obtained results indicate for a high radiation resistance of investigated materials. The irradiated samples exhibit up to 35% higher compressive strength in comparison with the native samples with retaining other parameters unchanged. According to the XRD, FTIR and DSC analyzes, the proposed mechanism laying behind enhancement of mechanical properties of SPC is the sulfur polymer binder amorphization with a possible simultaneous radiation induced polymerization and/or crosslinking. The SPC materials can be considered as promising alternative for hydraulic cement concrete composites, especially in radiation and nuclear technology sectors.

Reactive Compression Molding Post-Inverse Vulcanization: A Method to Assemble, Recycle, and Repurpose Sulfur Polymers and Composites.

Inverse vulcanization provides dynamic and responsive materials made from elemental sulfur and unsaturated cross-linkers. These polymers have been used in a variety of applications such as energy storage, infrared optics, repairable materials, environmental remediation, and precision fertilizers. In spite of these advances, there is a need for methods to recycle and reprocess these polymers. In this study, polymers prepared by inverse vulcanization are shown to undergo reactive compression molding. In this process, the reactive interfaces of sulfur polymers are brought into contact by mechanical compression. Upon heating these molds at relatively low temperatures (≈100 °C), chemical bonding occurs at the polymer interfaces by S-S metathesis. This method of processing is distinct from previous studies on inverse vulcanization because the polymers examined in this study do not form a liquid phase when heated. Neither compression nor heating alone was sufficient to mold these polymers into new architectures, so this is a new concept in the manipulation of sulfur polymers. Additionally, high-level ab initio calculations revealed that the weakest S-S bond in organic polysulfides decreases linearly in strength from a sulfur rank of 2 to 4, but then remains constant at about 100 kJ mol-1 for higher sulfur rank. This is critical information in engineering these polymers for S-S metathesis. Guided by this insight, polymer repair, recycling, and repurposing into new composites was demonstrated.

Improving the Aging Resistance of Asphalt by Addition of Polyethylene and Sulphur

With the increase in demand of flexible pavements, due to their various advantages over rigid pavements, there is a need to improve the aging properties of the bitumen in order to enhance its resistance against different types of distresses such as rutting, fatigue cracking. This research focus on the use of one polymeric additive Polyethylene (PE) and one non polymeric additive Sulphur (S) to enhance the aging resistance of asphalt. These modifiers are evaluated for their effect on the aging mechanism in comparison with the unmodified bitumen. Aging of the original and modified bitumen is realized by the Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV). Physical properties of the aged and unaged asphalt binders are evaluated through empirical testing like penetration, ductility and softening point test. Optimum content of the modifiers is obtained by comparing the results of conventional properties before and after aging. Fourier Transformed Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) are performed to bring out the chemical and morphological changes in the modified binder. Rheological properties of modified asphalt are evaluated with the help of a Dynamic Shear Rheometer (DSR). Results indicate improvement in physical properties of the modified asphalt even after the aging. Penetration index increased which shows less temperature susceptibility of the modified binders. Carbonyl and sulfoxide index are used as aging indicators which shows reduction in case of modified samples. Decrease in the sulfoxide and carbonyl index indicates better oxidation resistance of the modified samples. Morphological analysis proves good compatibility of the modifiers with asphalt binders. DSR results indicate improved viscoelastic properties of the modified binders. Hence it can be concluded that Polyethylene and Sulphur are good options to improve the aging resistance of asphalt in terms of their cost effectiveness and environment friendly nature.

Tung oil as an effective modifier for sulfur polymer cement and its performance in galvanic waste encapsulation

The data on the performance of sulfur polymer cement crosslinked with tung oil polymerization modifier are presented. Specimens of sulfur polymer cement (SPC) were prepared with different doses of tung oil in amounts of up to 8.85% of the sulfur mass. The obtained SPCs were used as binders to encapsulate two galvanic wastes differing in their toxic metal composition: waste I and waste II with loadings of approximately 25 and 50% of the composites' mass, respectively. For comparative purposes, appropriate samples of the SPCs and their composites with galvanic wastes were obtained using very similar doses of dicyclopentadiene sulfur modifier. Waste II was also encapsulated using SPC, in which a mixture of tung oil and dicyclopentadiene in a 1:1 weight ratio was used as the modifier. Crosslinking of the tung oil to the SPC matrix was assessed by FT-IR. The obtained SPCs and their composites with galvanic wastes were characterized by SEM and tested for water sorption capacity, compressive strength and metal leaching toxicity using TCLP and EN standards. The effectiveness of the tung oil binding to the SPC network was evidenced by the complete disappearance of methine C–H stretching vibrations at 3010 cm−1 and the double bond –C=C– wagging vibrations at 990 cm−1 in the FT-IR spectrum after processing with sulfur. SEM observations revealed that all the specimens prepared with dicyclopentadiene had a glassy-like fracture surface and also showed fewer cavities and defects in cements and composites when compared to their counterparts prepared with tung oil. The water sorption capacities of all the specimens were below 1%, where the values of those prepared with the tung oil were two to three fold higher than the values of their counterparts prepared with dicyclopentadiene. The pH of the TCLP leachates was in the range of 2.75–2.98, and a decreasing trend in the pH value was found with an increasing modifier dose. The TCLP leachate pH from the waste I monoliths with dicyclopentadiene were generally lower by 0.1–0.35 when compared to the corresponding monoliths with tung oil. The toxic metals immobilization order revealed from the TCLP test (leachate pH around 2.85) is Cd > Sr ≥ Zn > Cu > Ni > Cr > Pb, while the resulting order from the EN test, due to a higher leachate pH of about 5.9, follows Cd > Pb > Zn > Cu ≥ Ni > Sr > Cr. An increased tung oil dose from 2 to 8.85% enhanced the SPC compressive strength by three to four fold, while the same increase of the dicyclopentadiene dose led to an increase of this parameter for less than two fold. The addition of galvanic wastes to the SPCs resulted in a further increase in compressive strength for the corresponding SPC samples.

Sulfur-containing emulsions under alternative non-thermal initiation: a way to increase the energy efficiency of chemical processes

Currently, there is a tendency to develop chemical and chemical-technological processes that consume as little energy as possible. Recently, ionizing and microwave radiation began to be used for these purposes in the chemical industry, since conventional heating can be slow and inefficient, which increases energy consumption. Polymer sulfur, which is one of the modifications of elemental sulfur, has a number of valuable properties, however, the existing methods for its synthesis are characterized by high energy consumption and therefore are disadvantageous. In order to develop a more efficient method for the synthesis of polymer sulfur, the processes that occur in sulfur-containing emulsions under the influence of ionizing and microwave radiation, and the products formed in these processes are investigated.

Investigating the Antibacterial Properties of Inverse Vulcanized Sulfur Polymers.

More than 60 million tons of sulfur are produced as a byproduct of the petrochemical industry annually. Recently, the inverse vulcanization process has transformed this excess sulfur into functional polymers by stabilization with organic cross-linkers. These interesting new polymers have many potential applications covering diverse areas. However, there has been very little focus on the potential of these high-sulfur polymers for their antibacterial properties. These properties are examined here by exposing two common bacteria species, Escherichia coli (E. Coli) and Staphylococcus aureus (S. aureus), to two structurally different, inverse vulcanized sulfur polymers: sulfur-co-diisopropenyl benzene (S-DIB) and sulfur dicyclopentadiene (S-DCPD). We report the highest bacteria log reduction (>log 4.3) of adhered bacterial cells (S. aureus) to an inverse vulcanized sulfur polymer to date and investigate the potential pathways in which antibacterial activity may occur.

Possible Formulations of Oil Binders Using Plant Materials

The effect of sulfur, polymeric petroleum resin and castor oil on the structural and mechanical characteristics of petroleum-based bitumen binders has been studied. On the basis of tar, binders were obtained that meet the requirements for road bitumen. It was noted that vegetable oil is highly effective as a modifying agent of bitumen properties. In samples containing polymeric petroleum resin, sulfur and vegetable oil, changes in some characteristics of bitumen are demonstrated: penetration, ductility, softening point. The fundamental possibility of modifying the properties of oil binders through the use of inexpensive oil products and vegetables oil, and as a result, the increase of hydrocarbon resource base for production of road bitumen through the involvement of alternative sources of raw materials, is shown.

Polymeric Sulfur as a Li Ion Conductor.

The typical polymer electrolyte matrix has been limited to the chains consisting of -C-C- or -C-O-C- or -Si-O- backbone with different solvating groups for decades. In this work, the polymeric sulfur consisting of -(S-S)n- backbone with a high sulfur content (up to 90 wt % S) was reported for the first time. The flexible -(S-S)n- chains with high S atom density create an intense "solvating" environment for Li+ conduction, achieving an excellent Li+ conductivity of 1.69 × 10-3 S cm-1 at 80 °C. Benefiting from its unique thermoplasticity, a hot-rolling process was also developed for fabricating the poly-S membrane. The symmetric solid-state Li cell using the membrane showed a high cycling stability over 300 h. The work offers a novel platform for chemists to design new polymer electrolytes that are quite different with conventional carbon-based polymer electrolytes.

Thermodynamic estimination of adsorption ability of modified zeolites

The article presents the results of original investigations of the thermodynamic laws of sorption extraction of Ni2+, Zn2+, Cu2+from wastewater. As an adsorbent, a natural zeolite from the Holinsky deposit of the klinoptilolite type, modified with a sulphur polymer, obtained from waste in the production of epichlorohydrin was proposed. The limiting parameters of the adsorption process are described by the Langmuir equation. The graphical method the limiting value of adsorption, the adsorption equilibrium constant, the differential heat of adsorption, the adsorption rate constant, the activation energy, the Gibbs energy was founded. It is proved that the investigated processes obey the laws of physical adsorption and are spontaneous.

Investigation of sorption characteristics of modified klinoptilolites by the method of infra-red energy and differential X-ray spectroscopy

The article presents investigations of adsorption of heavy metal ions Ni2+, Zn2+, Cu2+ by modified zeolites. As a modifier of zeolites of the Holinsky deposit, a sulfur polymer is proposed that is obtained from waste during the production of epichlorohydrin, the main components of which is 1,2,3 - trichloropropane. The mechanisms of adsorption and the results of investigations by the methods of infra-red pectroscopy and energy differential X-ray spectroscopy of the initial samples of materials are described in detail. On the IR- spectres new absorption bands are considered. These bands reflect the nature of fixation of modifier on the surface of sorbent.

Synthesis of sulfur-co-polymer/porous long carbon nanotubes composite cathode by chemical and physical binding for high performance lithium-sulfur batteries

The composite cathode of sulfur-rich polymer and long cylindrical porous multiwalled carbon nanotubes (LCNT) is reported for high performance lithium-sulfur (Li–S) batteries through combining both chemical and physical binding strategies of sulfur, respectively. This technique efficiently exploits the synergistic effect of ability of stabilizing the polymeric sulfur. The role of uniform distribution of highly conductive LCNT network is optimized as a cathode host material by solution route. Annealed sulfur-co-polymer (S-co-poly) composites are homogeneously well attached via physisorption with LCNT submicron channel. The composite shows a high discharge capacity of 1040 mAh g−1 in the 1st cycle of galvanostatic charge-discharge at 0.5C. Whereas, the cell maintains a reversible capacity of 610 mAh g−1 after 200 cycles, showing good capacity rate. Therefore, solvent assisted both synthesis and further proper mixing enables high active material utilization whereas porous submicron channel of CNT network, which provides conducting pathway, adsorbs sulfur copolymer homogeneously for better electrochemical performance.

Dendrite-like carbon nanotube-confined polymeric sulfur as cathode materials for lithium–sulfur battery

We reported the synthesis of dendrite-like carbon nanotube-confined polymeric sulfur composite by modifying the surface of carbon nanotubes (CNTs) with trithiocyanuric acid (TTCA) and then copolymerizing with sulfur. DSC results show the successfully formation of robust chemical bonds between sulfur and TTCA modified CNTs, which effectively avoid the dissolution of polysulfide when used as cathodes for lithium–sulfur batteries. The composite with a high sulfur content of 78 wt% exhibits an initial charge capacity of 698 mAh g−1 and the residual capacity of 553 mAh g−1 after 1000 cycles at a rate of 1 C.

DEVELOPMENT OF ACIDIC, ALKALINE, AND SALINE ENVIRONMENTALLY RESISTANT SULFUR POLYMER AND SPENT FCC CATALYST CONCRETE AS PROMISING ALTERNATIVE CONSTRUCTION MATERIAL

DEVELOPMENT OF ACIDIC, ALKALINE, AND SALINE ENVIRONMENTALLY RESISTANT SULFUR POLYMER AND SPENT FCC CATALYST CONCRETE AS PROMISING ALTERNATIVE CONSTRUCTION MATERIAL

Chemically induced repair, adhesion, and recycling of polymers made by inverse vulcanization.

Inverse vulcanization is a copolymerization of elemental sulfur and alkenes that provides unique materials with high sulfur content (typically ≥50% sulfur by mass). These polymers contain a dynamic and reactive polysulfide network that creates many opportunities for processing, assembly, and repair that are not possible with traditional plastics, rubbers and thermosets. In this study, we demonstrate that two surfaces of these sulfur polymers can be chemically joined at room temperature through a phosphine or amine-catalyzed exchange of the S-S bonds in the polymer. When the nucleophile is pyridine or triethylamine, we show that S-S metathesis only occurs at room temperature for a sulfur rank > 2-an important discovery for the design of polymers made by inverse vulcanization. This mechanistic understanding of the S-S metathesis was further supported with small molecule crossover experiments in addition to computational studies. Applications of this chemistry in latent adhesives, additive manufacturing, polymer repair, and recycling are also presented.

Thermal Stability Change of Insoluble Sulfur by a Heat Treatment and Its Mechanism Study.

Insoluble sulfur (IS), used as a vulcanizing reagent of rubber, is prepared by the thermal ring-opening polymerization of sulfur (S8). Enhancing its thermal stability and content ratio (yield) is important for the industrial production of IS. The post-heating process at a high temperature of 70 or 90°C of the mixture of IS and S8 enhanced the thermal stability of IS and reduced the yield of IS. Further, the process at 30°C enhanced its thermal stability and maintained its yield. Since the thermal stability of IS is considered to be closely related to the chain length of polymer sulfur, a method for determining the chain length of IS was investigated by quantifying the amount of electron spin of radicals from sulfur, estimated from electron spin resonance (ESR) measurements. We confirmed that the long-period post-heating process at 30°C induced high thermal stability without reducing the yield of IS due to growth of the sulfur polymer chains.

The fatigue behavior of polymeric sulfur-modified asphalt mixtures subjected to freeze-thaw conditioning

Abundance, affordability, and also the usability of sulfur as a part of the binder are the main reasons for using this additive in asphalt mixtures. However, lack of proper adhesion and brittle behavior of sulfur-modified asphalt mixtures could make them susceptible to moisture damage and fatigue cracking. In this regard, anti-stripping agents and some polymers like crumb rubber may be used to overcome these types of distresses. This research aimed at investigating the effects of polymeric sulfur and crumb rubber on the moisture sensitivity and fatigue behavior of asphalt mixtures. To this end, asphalt mixtures were subjected to 1 and 3 freeze-thaw cycles. Then, an indirect tensile fatigue test was carried out. Moreover, the response surface method (RSM) was used to assess the interaction between various parameters in samples containing polymeric sulfur and crumb rubber. Results showed that with an increase in polymeric sulfur content, the fatigue life was reduced and the moisture sensitivity was increased. Additionally, the RSM was found to be effective in ranking parameters influencing the performance of asphalt mixtures. According to the experimental results, a crumb rubber-modified binder could improve the fatigue life of the polymeric sulfur-modified mixture up to 70%. Furthermore, experimental results and RSM analysis indicated that crumb rubber would be more effective in higher numbers of freeze-thaw cycles and raised temperatures, in which polymeric sulfur-modified asphalt mixtures are probably prone to moisture damages (i.e. the lack of adequate cohesion and adhesion).

Features of Influence the Temperature on the Electrochemical Parameters of Li-Battery with Cathode Based on Polymer Sulfur. Impedance and Galvanostatic Cycling

The effect of temperature on 1) impedance and discharge –charging characteristics of Li-S cells during cycling, and 2) the conductivity of non-aqueous electrolyte that is used in this system have been investigated. Particular attention is paid to the hysteresis of the conductivity in the temperature range from minus 25 °C to plus 60 °C and then back to plus 25 °C.

Innovating Cathode Based on Polymer Sulfur for Stable and Safer Lithium-Sulfur Batteries

The comparative characteristics of sulfur allotropes (orthorhombic and polymeric) in Li –S cells have been presented. The difference in the structure and physico-chemical properties of the initial material has been shown. The electrochemical properties of S-based cathodes in non-aqueous liquid electrolyte (0.7 M LiIm, 0.25 M LiNO3, DME: DOL (2:1) in lithium rechargeable batteries have been investigated.