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1.
G. V. Romanov R. G. Fitzeva I. V. Konovalova A. N. Pudovik N. P. Burmistrova 《Journal of Thermal Analysis and Calorimetry》1974,6(1-2):119-130
The application of DTA with the simultaneous recording of electrical conductivity variation in the study of the thermal behaviour ofα-oxyalkylphosphonates and their analogues is considered. The investigation of electrical conductivity variation during a reaction helps clarify certain problems of the phosphonate-phosphate rearrangement and the decomposition ofα-oxyalkylphosphonates to their components. 相似文献
2.
Polymer electrolyte systems were prepared for the first time by dissolution of amidomagnesium chlorides in poly(ethylene oxide),
(PEO). For the preparation, solutions of (hexamethyldisilylamido)magnesium chloride, (dimethylpyrrolyl)magnesium chloride,
(diisopropylamido)magnesium chloride, piperidinomagnesium chloride and morpholinomagnesium chloride were chosen. The composition
of these polymer electrolyte systems corresponds to the general formula R2NMgCl·P(EO)n·THF. Most work has been done with the system (hexamethyldisilylamido)magnesium chloride in PEO, (Me3Si)2NMgCl·P(EO)n·THF, with n= 3, 4, 5, or 7. The electrolytes have a soft rubber-like consistency. At 30 °C, electrical conductivities of 10−6–10−5 S/cm were found. The conductivities were measured in the temperature range 20–60 °C. Within this temperature range a linear
dependence of the logarithms of the conductivity on the inverse temperature was found and activation energies for the conducting
process of 30–60 kJ/mol were calculated. Using those polymer electrolytes with a high content of the amidomagnesium compound,
a reversible magnesium deposition takes place by cathodic reduction at potentials below −1.9 V vs. a Ag/AgCl reference electrode.
These polymer electrolytes were found to be stable against oxidation up to about −0.3 V vs. Ag/AgCl.
Electronic Publication 相似文献
3.
Munehisa Yasuniwa Shinsuke Tsubakihara Takahiro Murakami 《Journal of Polymer Science.Polymer Physics》2000,38(1):262-272
Pressure effect on the melting behavior of poly(butylene terephthalate) (PBT) and poly(hexamethylene terephthalate) (PHT) was studied by high‐pressure DTA (HP‐DTA) up to 320 and 530 MPa, respectively. Cooling rate dependence on the DSC melting curves of the samples cooled from the melt was shown at atmospheric pressure. Stable and metastable samples were prepared by cooling from the melt at low and normal cooling rates, respectively. DTA melting curves for the stable samples showed a single peak, and the peak profile did not change up to high pressure. Phase diagrams for PBT and PHT were newly determined. Fitting curves of melting temperature (Tm) versus pressure expressed by quadratic equation were obtained. Pressure coefficients of Tm at atmospheric pressure, dTm/dp, of PBT and PHT were 37 and 33 K/100 MPa, respectively. HP‐DTA curves of the metastable PBT showed double melting peaks up to about 70 MPa. In contrast, PHT showed them over the whole pressure region. HP‐DTA of stable poly(ethylene terephthalate) (PET) was also carried out up to 200 MPa, and the phase diagram for PET was determined. dTm/dp for PET was 49 K/100 MPa. dTm/dp increased linearly with reciprocal number of ethylene unit. The decrease of dTm/dp for poly(alkylene terephthalate) with increasing a segmental fraction of an alkyl group in a whole molecule is explained by the increase of entropy of fusion. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 262–272, 2000 相似文献
4.
The Na/Tl exchange is investigated in two silicate glasses (Na2O·2SiO2 and crown-flint KF3) by estimation of concentration or refractive index profiles, resp. (c
Tl(x) orn(x)). The forms of the profiles are discussed in connection with changes of the glass transition temperature Tg owing to an increase of Tl2O contents, determined by DTA on homogeneous glass samples. During the Na/Tl exchange the local and temporal enlargement of the Tl2O content causes a drastic decrease ofT
g(x, t) values and of the viscosity (x, t), which yields a remarkable acceleration of the Na/Tl interdiffusion.
Zusammenfassung Der Na/Tl-Austausch wird in zwei Silicatgläsern (Na2O.2SiO2 und Kron-Flintglass KF3) anhand der Bestimmung von Konzentrations- oder Brechzahlprofilen (c Tl(x) odern(x)) untersucht. Die Profilformen werden im Zusammenhang mit Änderungen der Glastransformations-TemperaturT g bei steigendem Tl2O-Gehalt diskutiert, die mittels DTA an homogenen Glasproben bestimmt wurden. Während des Na/Tl-Austausches verursacht die lokale und zeitliche Erhöhung des Tl2O-Gehaltes ein drastisches Absinken derT g(x, t)-Werte bzw. der Viskosität (x, t), das zu einer bemerkenswerten Beschleunigung der Na/Tl-Interdiffusion führt.
(Na2O.2SiO2 «») Na/Tl 1(x) 321in(x). , , . Na/Tl g(, t) i (x,t), Na/Tl .相似文献
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José L. de la Fuente Marta Ruiz-BermejoCésar Menor-Salván Susana Osuna-Esteban 《Polymer Degradation and Stability》2011,96(5):943-948
This paper presents a thermogravimetry (TG) study of hydrogen cyanide polymers, synthesized from the reaction of equimolar aqueous solutions of sodium cyanide and ammonium chloride. Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were also used to evaluate the thermal behaviour of these black polymers, which play an important role in prebiotic chemistry. A coupled TG-mass spectrometer (MS) system allowed us to analyze the principal volatile thermal decomposition and fragmentation products of the isolated HCN polymers under dynamic conditions and an inert atmosphere. After dehydration, a multi-step decomposition occurred in this particular polymeric system, due to the release of ammonia, hydrogen cyanide (depolymerization reaction), isocyanic acid (or cyanic acid) and formamide; these two latter species allow us identify bond connectivities. Finally, data collected from TG experiments in an oxidative atmosphere showed significant differences at higher temperatures, above 400 °C. According to these results, the different techniques of thermal analysis here applied have demonstrated to be an adequate methodology for the study and characterization of this complex macromolecular system, whose structure remains controversial even today. 相似文献
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A self-recording conductivity meter used by the Rotterdam Waterworks is described. The importance for the waterworks of this instrument for the controlling the water catchment is shown. 相似文献
8.
Kralchevsky PA Boneva MP Danov KD Ananthapadmanabhan KP Lips A 《Journal of colloid and interface science》2008,327(1):169-179
Here, we propose a method for determining the stoichiometry of acid-soap crystallites. The method is based on dissolving the crystallites in water at an appropriate working temperature, followed by measurement of the electrolytic conductivity of the obtained solutions. The working temperature is chosen in such a way that the only precipitate in the solutions is that of carboxylic acid, whereas the carboxylate salt is dissociated, and its content in the dissolved crystals determines the solution's conductivity. In the theoretical model for data interpretation, we took into account the dependence of the molar conductance on the ionic strength. The method was applied for determining the stoichiometry of acid-soap crystals collected from solutions of potassium myristate (tetradecanoate) at 25 degrees C. The crystals were dissolved in water at working temperature of 40 degrees C, at which the conductivity was measured. The stoichiometry of all samples determined in the present study coincides with that independently obtained by another method that is based on in situ pH measurements. 相似文献
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Journal of Thermal Analysis and Calorimetry - A new apparatus for measurement of electrical conductivity during thermogravimetric analysis is described. Results of an investigation of the... 相似文献
12.
Maurizi Enrici Tommaso Mertens Anne Sinnaeve Mario Tchuindjang Jérôme Tchoufang 《Journal of Thermal Analysis and Calorimetry》2020,141(3):1075-1089
Journal of Thermal Analysis and Calorimetry - In this work, a complex graphitic high-speed steel (Gr-HSS) obtained from a spin-casting process that allows high cooling rates during solidification... 相似文献
13.
Journaux Y Glaser T Steinfeld G Lozan V Kersting B 《Dalton transactions (Cambridge, England : 2003)》2006,(14):1738-1748
The ligating properties of the 24-membered macrocyclic dinucleating hexaazadithiophenolate ligand (L(Me))2- towards the transition metal ions Cr(II), Mn(II), Fe(II), Co(II), Ni(II) and Zn(II) have been examined. It is demonstrated that this ligand forms an isostructural series of bioctahedral [(L(Me))M(II)2(OAc)]+ complexes with Mn(II) (2), Fe(II) (3), Co(II) (4), Ni(II) (5) and Zn(II) (6). The reaction of (L(Me))2- with two equivalents of CrCl2 and NaOAc followed by air-oxidation produced the complex [(L(Me))Cr(III)H2(OAc)]2+ (1), which is the first example for a mononuclear complex of (L(Me))2-. Complexes 2-6 contain a central N3M(II)(mu-SR)2(mu-OAc)M(II)N3 core with an exogenous acetate bridge. The Cr(III) ion in is bonded to three N and two S atoms of (L(Me))2- and an O atom of a monodentate acetate coligand. In 2-6 there is a consistent decrease in the deviations of the bond angles from the ideal octahedral values such that the coordination polyhedra in the dinickel complex 5 are more regular than in the dimanganese compound 2. The temperature dependent magnetic susceptibility measurements reveal the magnetic exchange interactions in the [(L(Me))M(II)2(OAc)]+ cations to be relatively weak. Intramolecular antiferromagnetic exchange interactions are present in the Mn(II)2, Fe(II)2 and Co(II)2 complexes where J = -5.1, -10.6 and approximately -2.0 cm(-1) (H = -2JS1S2). In contrast, in the dinickel complex 5 a ferromagnetic exchange interaction is present with J = +6.4 cm(-1). An explanation for this difference is qualitatively discussed in terms of the bonding differences. 相似文献
14.
Allouche J Tyrode E Sadtler V Choplin L Salager JL 《Langmuir : the ACS journal of surfaces and colloids》2004,20(6):2134-2140
Two kinds of transitions can occur when an emulsified water-oil-ethoxylated nonionic surfactant system is cooled under constant stirring. At a water-oil ratio close to unity, a transitional inversion takes place from a water-in-oil (W/O) to an oil-in-water (O/W) morphology according to the so-called phase-inversion-temperature method. At a high water content, a multiple w/O/W emulsion changes to a simple O/W emulsion. The continuous monitoring of both the emulsion conductivity and viscosity allows the identification of several phenomena that take place during the temperature decrease. In all cases, a viscosity maximum is found on each side of the three-phase behavior temperature interval and correlates with the attainment of extremely fine emulsions, where the best compromise between a low-tension and a not-too-unstable emulsion is reached. The studied system contains Polysorbate 85, a light alkane cut oil, and a sodium chloride brine. All transitions are interpreted in the framework of the formulation-composition bidimensional map. 相似文献
15.
The cyclotetraphosphate ion (P(4)O(12)(4)(-)) as a PPN (PPN = (PPh(3))(2)N(+)) salt reacts with [MCl(cod)](2) (M = Rh, Ir; cod = 1,5-cyclooctadiene) to give the dinuclear complexes (PPN)(2)[[M(cod)](2)(P(4)O(12))], in which the two metal moieties are situated trans to each other with respect to the P(4)O(4) ring in the solid state. In solution, however, these complexes exist as mixtures of trans and cis isomers. On the other hand, the P(4)O(12)(4)(-) ion reacts with 4 equiv of [Rh(cod)(MeCN)(x)](+) cation to give the tetranuclear complex [[Rh(cod)](4)(P(4)O(12))], where the four Rh(cod) fragments are bound to the P(4)O(12) platform alternately on both sides of the P(4)O(4) ring. Dinuclear P(4)O(12) complexes of ruthenium and palladium are also synthesized. 相似文献
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A. Azioune M. Marcozzi V. Revello J.‐J. Pireaux 《Surface and interface analysis : SIA》2007,39(7):615-623
In this work, aluminium (Alclad 2024‐T3) substrates were cleaned by an r.f. (13.56 MHz) plasma, using argon (Ar), oxygen (O2) and a mixture of O2/Ar (50:50) gases. The effectiveness of plasma cleaning was checked in situ using X‐ray photoelectron spectroscopy (XPS) and ex situ using water contact angle measurements. XPS O/Al surface atomic ratios are in excellent agreement with those of the crystalline boehmite and the pseudoboehmite. Oxygen O 1s peak‐fitting was used to quantify the proportion of hydroxyl ions and the functional composition on the aluminium surface: the surface cleaned with O2 plasma contains 50% of aluminium hydroxides, the ones cleaned with Ar plasma and with Ar/O2 plasma contain, respectively, 25 and 37% hydroxyl ions. The binding energy separation between Al 2p and O 1s is characteristic of AlO(OH). Thin SiOx films were subsequently deposited from a mixture of hexamethyldisiloxane (HMDSO) and oxygen. In the absence of oxygen, a hydrophobic (Θ≥ 100° ) film characteristic of polydimethylsiloxane (PDMS) is formed: polysiloxane‐like thinner films (SiOx) are obtained with the introduction of oxygen. XPS and contact angle measurements confirmed both the composition and the structure of these films. More importantly, contact angle measurements using different liquids and interpreted with the van Oss‐Good‐Chaudhury theory allowed determination of the surface free energy of the deposited films: the calculated values of surface tension of the film formed from HMDSO/O2: (50/50) are in excellent agreement with those of reference silica‐based materials such as a silicon wafer and cleaned glass. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
19.
Copper(II) oxide was synthesized in a glass matrix by multiple cycles of impregnation of porous glass with an aqueous solution of copper nitrate, followed by dehydration and thermal decomposition of the salt. The electrical conductivity and its temperature dependences, measured during the progressive accumulation of copper(II) oxide in porous glass, are indicative of a gradual change from chains to 2D structures, eventually resulting in a conductive oxide monolayer. 相似文献
20.
İbrahim Erden Ali Erdoğmuş Nebahat Demirhan Ulvi Avcıata 《Transition Metal Chemistry》2008,33(4):439-442
A new fluorene ligand, benzo[15-crown-5]-5H-pyrido[3′,2′:4,5]cylopenta[1,2-b]pyridin-5-ylidenehydrazone (bph), has been synthesized from the reaction of 4,5-diazafluoren-9-one
with 4′-formylbenzo-15-crown-5. The Co(II), Cu(II), and Ru(II) complexes of the ligand were prepared and characterized. The
metal-to-ligand ratio of the Co(II) and Cu(II) complexes was found to be 2:1 and that of the Ru(II) complex was found to be
1:1. The ligand and complexes have been characterized by FTIR, UV–visible, 1H NMR and fluorescence spectra, as well as elemental analyses and mass spectra. 相似文献