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301.
Vincenzo Mirabello Maria Caporali Luca Gonsalvi Gabriele Manca Andrea Ienco Maurizio Peruzzini 《化学:亚洲杂志》2013,8(12):3177-3184
The selective functionalization of the polyphosphorus moiety Ph2PCH2PPh2PPPP present as a tetrahapto‐ligand in complex [Ir(dppm)(Ph2PCH2PPh2PPPP)]+ ( 1 , dppm=Ph2PCH2PPh2) was obtained by reaction of 1 with water under basic conditions at room temperature. The formation of the new triphosphaallyl moiety η3‐P3{P(O)H} was determined in solution by NMR spectroscopy, and confirmed in the solid state by a single‐crystal X‐ray structure of the stable product [Ir(κ2‐dppm)(κ1‐dppm)(η3‐P3{P(O)H})] ( 2 ). In solution, 2 has a fluxional behavior attributable to the four P atoms belonging to the tetraphosphorus moiety in 1 and exhibits a chemical exchange process involving the two PPh2 moieties of the same bidentate ligand, as determined by 1D and 2D NMR spectroscopy experiments carried out at variable temperature. The mechanism of the reaction was investigated at the DFT level, which suggested a selective attack of an in‐situ generated OH? anion on one of the non‐coordinated phosphorus atoms of the P4 moiety. The reaction then evolves through an acid‐assisted tautomerization, which leads to the final compound 2 . Bonding analysis pointed out that the new unsubstituted P3‐unit in the η3‐P3{P(O)H} moiety behaves as a triphosphallyl ligand. 相似文献
302.
Xiaofeng Wang Weiyi Xing Gang Tang Ningning Hong Weizhao Hu Jing Zhan Lei Song Wei Yang Yuan Hu 《Polymer Degradation and Stability》2013
A novel sulfur-bearing secondary antioxidant with a high molecular weight of 2252 (OS-POSS), successfully synthesized via photoinitiated thiol-ene click reaction, was compared with two commercial sulfur-bearing secondary antioxidants on the stabilization of polypropylene (PP). The results of their oxidation induction time (OIT) via differential scanning calorimeter measurement (DSC) showed that the higher the molecular weight of secondary antioxidant is, the longer the OIT value, whether such sulfur-bearing antioxidant is used singly or in combination with primary antioxidant. The study of their long-term accelerated thermal aging in the air oven at 150 °C displayed that the molecular structure of sulfur-bearing secondary antioxidant, besides molecular weight, is another highly important factor determining the antioxidant efficiency, i.e., physical loss of antioxidants with the relatively low molecular weight may determine antioxidant efficiency, whereas thioether groups having neighboring ester carbonyl moieties may decompose more hydroperoxides with quicker rate. 相似文献
303.
Brecht Van Hooreweder David Moens Rene Boonen Jean-Pierre Kruth Paul Sas 《Polymer Testing》2013,32(5):972-981
This paper describes the influence of dynamic tension/compression loading on notched and unnotched nylon specimens fabricated by Injection Molding (IM) and Selective Laser Sintering (SLS). The main objective of this work is to analyze and describe the differences in material structure and fatigue properties of as-built nylon parts produced by IM and SLM from the same polyamide 12 powder. The differences in dimensional quality, density, surface roughness, crystal structure and crystallinity are systematically measured and linked to the mechanical fatigue properties. The fatigue properties of the unnotched SLS specimens are found to be equal to those of the unnotched IM specimens. The presence of pores in the sintered samples does not lead to rapid failure, and the microvoid coalescence failure mechanism is delayed. The notched specimens show more brittle failure and increased fatigue resistance which is caused by local notch-strengthening. The results enable improved understanding of the difference in material structure and fatigue behavior of selective laser sintered and injection molded polyamide. 相似文献
304.
Zhaoyun Ding Liguo Zhou Shimin Fang 《Journal of Dispersion Science and Technology》2013,34(9):1342-1349
Effect of surfactants [polyglycerol diisostearate ethoxylates (PGDIS-E31, PGDIS-E36 and PGDIS-E40) and Tween-80], alcohols (1,2-propandiol, ethanol, 1-propanol, 1-butanol, 2-butanol and 1-pentanol), oils [isopropyl palmitate (IPP), isooctyl palmitate (IOP), dioctyl carbonate (DOC), and dioctyl hexanediate (DOH)], temperature and sodium chloride on the microemulsion formation of the surfactant/alcohol/oil/water system has been investigated by the pseudo-ternary phase diagrams. The capacities of the four surfactants in the microemulsion formation of the surfactant/alcohol/IPP/water system at surfactant/alcohol of 2:1 are in the order of PGDIS-E31 > PGDIS-E36 > Tween-80 > PGDIS-E40, whatever alcohol (ethanol, 1-propanol, and 1-butanol) is used. PGDIS-E31 and 1-butanol exhibit best synergism in the microemulsion formation. In addition, the volume, structure and polarity of oil all influence the microemulsion formation. At the optimum weight ratio 2:1 of PGDIS-E31/1-butanol, the microemulsion region of the PGDIS-E31/1-butanol/IPP/water system is the largest among the studied systems. The microemulsion system of PGDIS-E31/1-butanol/IPP/water is not sensitive to lower temperature such as 40°C. It is also not sensitive to sodium chloride when the concentration of sodium chloride is in the range of 0 to 1.0%. 相似文献
305.
Ibrahim Kayali Mohammad Karaein Khawla Qamhieh Salam Wadaah Wisam Ahmad Ulf Olsson 《Journal of Dispersion Science and Technology》2013,34(1):10-17
Bicontinuous and water-in-diesel microemulsions were formulated using single nonionic alkyl poly glycol ethers combined with hydrophilic alcohol ethoxylates. The phase behavior at temperatures ranging from 0°C to 50°C was investigated. Visual inspection as well as cross-polarizers were used to detect anisotropy. The fish phase diagrams were determined. The presence of the hydrophilic alcohol ethoxylates was necessary to initiate both types of microemulsions. Increasing the hydrophobic chain length of the surfactant led to a wider range of temperature stability at lower surfactant concentration. Meanwhile, increasing the ethylene oxide units in the headgroup by two units led to a phase diagram that is dominated by lyotropic liquid crystal. The formulated water in diesel microemulsions were tested experimentally in a 4-cylinder diesel engine. From this it is observed that the emissions of NOx, soot, and CO2 were reduced substantially compared to neat diesel, while for the CO the reduction occurs just at low load. 相似文献
306.
Lok Kumar Shrestha 《Journal of Dispersion Science and Technology》2013,34(8):1236-1241
We have investigated the phase behavior of diglycerol monomyristate (DGM) in a variety of organic solvents over a wide range of temperatures and compositions. At lower temperature, there exists a surfactant solid, which solubilize different amounts of oils depending on the oil nature. The melting temperature of the solid phase is virtually constant in a wide range of composition. In all the systems, a lamellar liquid crystal (Lα) is formed in surfactant‐rich regions at intermediate temperatures between the solid‐melt and isotropic two‐ or single‐phase regions. In the dilute regions reverse vesicles are formed in the Lα+O regions mainly in the case of linear hydrocarbon type oils. In the aromatic and cyclic aliphatic oils, there are isotropic solutions at 25°C. However, there is dispersion of α‐solid in the case of liner hydrocarbon oils. Two liquid‐phase regions above the Lα phase are observed in the case of tetradecane and hexadecane. In the shorter chain oil systems, such as octane and decane, no two liquid‐phase appear above Lα region. That is the two liquid‐phase region is largely dependent on the chain length of the oils, and becomes wider in longer hydrocarbon oil. 相似文献
307.
Xia Dong 《Journal of Dispersion Science and Technology》2013,34(6):750-755
A series of dye-polyether derivatives, supposedly to be used as dispersants for parent dye, were synthesized by grafting poly(oxyalkylene)-amines based on differing both molecular weights and degrees of hydrophilicity/hydrophobicity, onto C.I. disperse red 60 via a stable urea linkage. The structures of the dye-polyether derivatives were characterized by FTIR, 1H NMR, and SEC. The influence of pH on the hydrolysis behaviors of the dye-polyether derivatives were studied in buffered aqueous solutions within the pH range of 4 to 10. The hydrolysis of dye-polyether derivatives was pH dependent and relatively faster in mild alkaline buffer solution than in acidic one. The influence of poly(oxyalkylene)-amine structure on the hydrolysis behavior was also investigated; it was found that the hydrolysis rate is affected little by the molecular weight and increases with the increasing hydrophilicity of the poly(oxyalkylene)-amine. 相似文献
308.
Multiple emulsions stabilized by colloidal microcrystalline cellulose (CMCC, Avicel RC591) at the w/o and o/w interfaces, and by the addition of Span 80 or Span 85 at the w/o interface, were studied by means of brightfield microscopy, freeze-etch electron microscopy, droplet size distribution analysis and rheologic measurements. Stable multiple emulsions were prepared by incorporation of sodium chloride in the innermost aqueous phase, thereby creating an osmotic gradient preventing loss of the inner aqueous phase to the external aqueous phase. Freeze-etch electron microscopy of the multiple emulsions indicated the presence of a network of microcrystalline cellulose at the outer o/w interface. It may be assumed that the surfactant directly stabilized the w/o interface by adsorption at the interface, as well as indirectly by facilitating wetting of the microcrystalline cellulose by the oil. From rheologic measurements, the existence of a three-dimensional network in the external aqueous phase was indicated by the considerable degrees of thlxotropy and significant static yield values of these multiple emulsions. 相似文献
309.
Heikki Torvela 《International journal of environmental analytical chemistry》2013,93(2):143-154
Abstract The determination of sulphur and heavy metals in plants is an integral part of many environmental studies. Pine needles (Pinus Sylvestris) have proved to be suitable air quality indicators for pollutants, especially for sulphur. This study was carried out in the vicinity of Kemi, a town situated on the Gulf of Bothnia in northern Finland. An industrial complex comprising two pulp and paper mills is located in the centre of the area. Scots pine (Pinus Sylvestris) needles were collected from 29 sampling sites. The samples were dried, homogenized and digested with nitric acid. The concentrations of the elements S, Fe, Zn, Ca, V, and Pb were determined by ICP-AES. According to our results pine needles (Pinus sylvestris) appear to be an ideal bioindicator and sampling material for identifying and assessing atmospheric sulphur pollution derived from pulp and paper mills and can complement the information provided by plant mapping studies around pulp and paper mills. 相似文献
310.
Abstract The use of methane chemical ionisation GC/MS gave satisfactory results when applied to environmental analysis of halogenated octylphenol polyethoxylates residues. In addition the selected ion monitoring GC/MS technique has been successfully applied for simulataneous qualitative and quantitative determination of some refractory metabolites of nonylphenol polyethoxylates in secondary sewage effluent and surface waters. 相似文献