Complete devulcanization of sulfur‐cured butyl rubber by using supercritical carbon dioxide

Sulfur‐cured butyl rubber was devulcanized completely in supercritical CO₂ by using diphenyl disulfide (DD) as a devulcanizing reagent. The optimum devulcanizing conditions were studied and the sol fraction of the reclaimed rubber obtained was up to 98.5%. The possible devulcanizing mechanism was investigated. Then, the sol component of reclaimed rubber was characterized by gel permeation chromatography, ¹H‐NMR, and differential scanning calorimetry, and the reclaimed rubber was characterized by TGA. Because of the substitution of a large portion of allylic hydrogen by sulfurated functional groups during vulcanization, the signal of the olefinic proton shift. As a result of the numerous decreases in the active crosslinking sites and the remaining DD, reclaimed rubber could not be cured by sulfur. At last, the blends of virgin butyl rubber and different contents of reclaimed rubber were revulcanized and their mechanical properties investigated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties of novel diallyl phthalate resin modified with sulfur‐containing allyl ester compounds

Sulfur‐containing allyl ester, which reacts with diallyl phthalate (DAP) resin to have allyl groups, was synthesized by the reaction of allyl phthalic acid with bisphenol having sulfur atoms. The sulfur‐containing allyl ester compound was blended with DAP resin to improve the adhesive properties to copper. By modification with sulfur‐containing allyl ester compound, the T‐peel adhesive strength and the lap shear adhesive strength to copper was improved. In particular, the adhesive strength was greatly improved when the resin was modified with the allyl ester compound having a disulfide bond (?S?S?) (DADS). It is concluded that this result is due to the improvement of the interfacial adhesive strength because the sulfur atom was found to be located in the surface of the copper by Fourier transform infrared (FTIR) analysis. The glass transition temperature (T_g) and the thermal decomposition temperature (T_d) of the cured DAP resin modified with DADS slightly decreased with increasing concentration of DADS. The lowering of T_g is because the crosslinking density of the DAP resin modified with DADS is smaller than that of DAP resin. Moreover, from thermogravimetric analysis, the lowering of Td of the DAP resin modified with DADS is because DADS is likely to pyrolyze. © 2013 Society of Chemical Industry     

Synthesis and application of a sulfur‐containing phosphoric amide flame retardant for nylon fabric

A sulfur‐containing flame retardant (SFR) was synthesized from polyphosphoric acid, epoxy chloropropane, and thiourea. Using a water‐soluble isocyanate‐terminated (WIT) cross‐linker, the flame retardant was applied as a flame‐retardant finishing on nylon fabric. WIT is a compound that not only cross‐links SFR and nylon cellulose but also contains no formaldehyde. Comparisons of the main performances of SFR with those of N‐methyloldimethylphosphonopropionamide (known as ‘Pyrovatex CP’) and a bicyclic phosphonite (known as ‘Antiblaze 19T’) indicate that the presence of sulfur in SFR plays a crucial role in decreasing the flammability of the nylon fabric. The limiting oxygen index value and damaged carbon length of the finished nylon fabric were 29.4% and 5.7 cm, respectively, when the concentrations of SFR and WIT were 200 and 40 g/L, respectively, and the baking temperature and time were 150 °C and 3 min, respectively. After 10 laundry cycles, the fabric still retains some flame retardancy. Copyright © 2016 John Wiley & Sons, Ltd.     

The identity of the sulfur‐containing phases present in cement clinker manufactured using a high sulfur petroleum coke fuel

Cement clinker produced using a high sulfur petroleum coke fuel has been analysed to determine the identity of the sulfate‐containing phases. Quantitative X‐ray diffraction methods were used in conjunction with extraction procedures to concentrate or extract the sulfate phases. The minerals of interest were anhydrite (CaSO₄), aphthitalite (3K₂SO₄·Na₂SO₄), arcanite (K₂SO₄), calcium langbeinite (K₂SO₄·2CaSO₄) and thenardite (Na₂SO₄). Overall sulfur content of the clinker increased in proportion with the amount of sulfur in the fuel. The clinker produced using the high sulfur fuel was found to contain a significantly increased concentration of aphthitalite but a reduced amount of thenardite. Comparison of the experimental results with theoretical predictions based on the Bogue formulae shows differences in respect of calcium langbeinite, which is not detected in the clinker, and thenardite, which is detected. Copyright © 2004 Society of Chemical Industry     

Study on the optical properties of sulfur‐containing poly(methyl methacrylate)‐inorganic hybrid

High refractive index homogeneous hybrid materials were successfully prepared. The polymer matrix was the copolymer of methyl methacrylate, sulfur‐containing monomer 2,2′‐mercaptoethylsulfide dimethacrylate (MESDMA), and nanotitania was prepared by in situ solgel process of titanium n‐butoxide. The transmission electron microscope (TEM) study suggested that the hybrid was homogeneous without inorganic agglomerate, and the inorganic particles were 4–7 nm. The refractive index was ～ 1.75 when the inorganic content of the hybrid film reached to 70 wt %, and the transmittance maintained up to 85%. The sulfur‐containing monomer was used to improve the refractive index, also, it was a crosslinking reagent, which improved the film‐forming ability of the hybrid. After copolymerized with MESDMA, the film‐forming ability of the hybrid was better than the one without MESDMA. Even if the inorganic content exceeded 75 wt %, the films kept integrity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Optical material of high refractive index resin composed of sulfur‐containing aliphatic and alicyclic methacrylates

A resin having a high refractive index and a high Abbe number was produced by radical polymerization of a polymerizable monomer mixture composed of essentially sulfur‐containing aliphatic methacrylates or alicyclic methacrylates. We provide an optical material composed of said resin, specifically, a lens. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 45–49, 2000     

Synthesis of a phosphorus and sulfur‐containing aromatic diamine curing agent and its application in flame retarded epoxy resins

A novel curing agent of epoxy resins (EPO), bis(3‐amino‐2‐thienyl) phenylphosphine oxide (ABTPPO), was synthesized and characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and ³¹P NMR. ABTPPO was used as a flame retardant curing agent, and a novel halogen‐free flame retardant EPO composite was prepared. The flame retardant properties of ABTPPO‐cured EPO were evaluated in terms of limiting oxygen index and vertical burning test (UL‐94), while the combustion and thermal degradation behaviors were investigated by cone calorimeter test (CONE) and thermogravimetric analysis, respectively. The cured EPO composite passed the UL‐94 V‐1 and V‐2 rating when the sample thickness is 3.0 and 1.6 mm, respectively, and the limiting oxygen index value reached 38.3%. The morphological structures of char residue tested by scanning electron microscopy demonstrated that ABTPPO benefited to the formation of a more compact and homogeneous char layer on the materials' surface during burning, which protected the underlying matrix from decomposition and enhanced the flame retardancy of materials. The cured EPO showed excellent fire performance after the water resistance test because of the low water uptake (0.6 wt%), which demonstrated that the flame retardant EPO composite possessed excellent water resistance property. Copyright © 2014 John Wiley & Sons, Ltd.     

Functionalization of low‐molecular‐weight oligomer dienes and olefins with sulfur‐ and oxygen‐containing compounds

The functionalization of piperylene fractions, oligodienes, and oligo‐olefins by elemental sulfur and phenols was carried out. The functionalized compounds were shown to be multipurpose additives, exhibiting high antiwear and antiscuff properties and simultaneously antioxidant and viscous properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3097–3105, 2006     

Nonhalogen flame retarded poly(butylene terephthalate) composite using aluminum phosphinate and phosphorus‐containing deoxybenzoin polymer

Synergistic charring effect was observed between aluminum diethlyphosphinate (AlPi) and 4,4‐bishydroxydeoxybenzoin‐polyphosphonate (BHDB‐PPN) in the poly(butylene terephthalate) composite. By combining them together, robust UL 94 V0 rating was achieved at 0.8 mm thickness for poly(butylene terephthalate)/AlPi/BHDB‐PPN composite which exhibited better mechanical properties than the samples without BHDB‐PPN. The thermal degradation behavior of BHDB‐PPN was investigated by analyzing its evolution and residues under different temperatures. It was found that the radical termination reaction of formed benzyl group may play a critical role in the high charring capacity of BHDB‐PPN. Part of the volatile diethlyphosphinate fragments reacted with the degradation intermediates from BHDB‐PPN to form big chain structure for further carbonization was a possible reason for the synergistic charring effect between AlPi and BHDB‐PPN. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45537.     

Chitosan functionalization with a series of sulfur‐containing α‐amino acids for the development of drug‐binding abilities

Chitosan (Chi; 0.5 g) in 69.66 mM aqueous acetic acid was mixed with 312.4 mM methionine (methi) at 0.01 mL/s to disperse and cause optimum collisions for supporting condensation reactions through ? NH₂ of Chi and ? COOH groups of methi. The functionalized chitosan (f‐Chi) product with methi developed an amide bond, which was represented as methi‐functionalized chitosan [Chi–NH? C(?O)–methi]. Both the 1‐Ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) and Dean–Stark methods were followed for Chi functionalization. Sulfonation with chlorosulfonic acid in a dimethylformamide medium was conducted at 90 °C and 750 rpm with an approximately 72% yield. The Chi–NH? C(?O)–methi was characterized by ¹H‐NMR spectroscopy and Fourier transform infrared stretching frequencies. The onset temperature of 280 °C recorded by thermogravimetric analysis/differential scanning calorimetry analysis, confirmed the high stability of the covalent bonds in Chi–NH? C(?O)–methi. The synthesis was repeated with other series members of sulfur (S) atoms containing α‐amino acids: homocysteine, ethionine, and propionine. The shielding of terminal ? CH₃ was enhanced on elongation of the terminal alkyl chain in the case of propionine. The peak for the ? NH₂ of Chi at a δ value of 4.73 ppm shifted to 5.36 ppm in Chi–NH? C(?O)–methi because of the involvement of ? NH₂ in ? NH? C(?O)? . Theoretically, the value of ? NH₂ of Chi was 5.11 ppm, with a difference of 0.38 ppm as compared to the experimentally determined value of 4.73 ppm. Additionally, a new peak at a δ value of 3.26 ppm also confirmed Chi functionalization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46000.     

Anaerobic Palladium‐Catalyzed Chemoselective Oxidation of Allylic and Benzylic Alcohols with α‐Bromo Sulfoxide as a Co‐oxidant

A chemoselective palladium‐catalyzed anaerobic oxidation of allylic and benzylic alcohols using an α‐bromo sulfoxide as a co‐oxidant is described for the first time. The catalyst system is simple and has a long life because of the allowance of phosphane ligands under the non‐aerobic conditions. The advantages of the described method include no overoxidation of primary alcohols to carboxylic acids because of the mild conditions applied, the tolerance of oxygen‐sensitive functionalities such as a carbon‐carbon double bond, an organothio group, or a diorganoamino group and the effective preparation of α,β‐unsaturated aldehydes and ketones, resulting from the oxidation of primary and secondary allylic alcohols, since a competitive Heck reaction with the co‐oxidant does not occur.     

Process intensification using a two‐phase system and micromixing for consecutive and reversible reactions

This study aimed to find reaction conditions that improve the yield of target intermediate products, using a two‐phase system and a microspace for first‐order consecutive and reversible reactions. As a result, the yield of target products with a two‐phase system can be surpassed by that of a single‐phase system through selecting the organic phase such that the partition coefficient of the raw material to the aqueous phase is large, and that of the target product to the organic phase is also large. In addition, the volume ratio of two phases and the liquid–liquid interfacial area are also important factors for improving the target product yield. In a microspace, the microfluid segments can be designed both arbitrarily and precisely, and thus it is possible to control the interfacial area and mass transfer rates accurately. Utilization of a microspace can play a significant role in intensifying a two‐phase system. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Thermal degradation behaviors of polypropylene with novel silicon‐containing intumescent flame retardant

The N‐[3‐(dimethoxy‐methyl‐silanyl)‐propyl]‐N′‐ (9‐methyl‐3,9‐dioxo‐2,4,8,10‐tetraoxa‐3,9‐diphospha‐spiro[5.5]undec‐3‐yl)‐ethane‐1,2‐diamine/dimethoxy dimethyl silane copolymer (PSiN II), which simultaneously contains silicon, phosphorus, and nitrogen, is synthesized and incorporated into polypropylene (PP). The flame retardancy is evaluated by the limiting oxygen index value, which is enhanced to 29.5 from 17.4 with 20% total loading of PSiN II. The thermal degradation behavior of PP/PSiN II is investigated by thermogravimetric analysis under N₂ and air. The PP/PSiN II sample degrades at 400°C for different amounts of time, and the process of degradation is studied by Fourier transform IR. The morphology of the char formed at 400°C for 10 min is investigated by scanning electron microscopy. The swollen inner structure, close, and smooth outer surface provide a much better barrier for the transfer of heat and mass during fire and good flame retardancy. The thermal stability of PP is improved by incorporation of PSiN II. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2487–2492, 2005     

Adsorption of nitrogen‐ and sulfur‐containing compounds on NiMoS for hydrotreating reactions: A DFT and vdW‐corrected study

Adsorption of 35 molecules, comprising of organonitrogen and organosulfur compounds and hydrocarbons relevant to hydrotreating, was studied on the nickel‐promoted metal edge of molybdenum sulfide catalysts using periodic DFT, accounting for van der Waals interactions in several cases. Basic molecules tend to adsorb via their nitrogen atoms directly on top of nickel atoms while nonbasic molecules adsorb via carbon atoms relatively weakly. Molecular size, electron density, and alkyl substitution affects binding at the GGA‐PW91 level of theory. van der Waals corrections influence adsorption geometry and lead to significant additional stabilization of adsorbates. The differential binding energy of nitrogen‐containing compounds decreases by 0.2–0.3 eV for each additional molecule added on the edge and their presence destabilizes the binding of organosulfur compounds by more than 0.2 eV. The inhibition of hydrodesulfurization is suggested to arise from site blocking and destabilization of reaction intermediates and transition states by organonitrogen compounds. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4036–4050, 2015     

Computational analysis of an instantaneous chemical reaction in a T‐microreactor

We extend and apply a method for the numerical computation of convective and diffusive mixing in liquid systems with very fast irreversible chemical reaction to the case of unequal diffusivities. This approach circumvents the solution of stiff differential equations and, hence, facilitates the direct numerical simulation of reactive flows with quasi‐instantaneous reactions. The method is validated by means of a neutralization reaction which is studied in a T‐shaped micromixer and compared with existing experimental LIF‐data. Because of their large are‐to‐volume ratio, microreactors are well suited for fast chemical reactions which are seriously affected by the slow diffusive transport in aqueous media. Numerical computations for different reactor dimensions reveal the fact that, in a dimensionless setting, the obtained conversion is independent of the reactor size, if the flow conditions are the same. This corresponds to an increase of space‐time‐yield proportional to the square of the inverse scale factor. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Pervaporation of organic compounds from aqueous mixtures using polydimethylsiloxane‐containing block copolymer membranes

Pervaporation of aqueous mixtures of ethanol, acetone, butanol, isobutanol, and furfural through polystyrene‐b‐polydimethylsiloxane‐b‐polystyrene (SDS) triblock copolymer membranes is reported. These mixtures are important for biofuel production from lignocellulosic feedstocks. Feedstock depolymerization results in the formation of furfural which must be removed before fermentation. Ethanol, butanol, isobutanol, and acetone are important fermentation biofuels. The membrane selectivity of SDS is about unity over a wide range of concentrations of aqueous ethanol mixtures, similar to the membrane selectivity of crosslinked polydimethylsiloxane (PDMS). The permeabilities of butanol, isobutanol, and furfural are larger than those of ethanol and acetone. The volatile organic compound permeability through SDS is similar to or higher than that through PDMS across a broad range of temperatures and feed concentrations is found. More selective and permeable membranes are needed to lower the cost of biofuel purification. The SDS membranes developed are but one step toward improved membranes. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2789–2794, 2015