Viscoelastic relaxation in the acetamide + sodium thiocyanate binary system

Berchiesi, G.; Vitali, G.; Passamonti, Paolo; Płowiec, R.

doi:10.1039/f29837901257

Cited by 43 publications

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“…In general, either negative or positive deviations in Tg or To with alkali ion concentration have been reported for mixed alkali systems in hydrate melts (4)(5)(6) or molecular liquids (8-1 1) but a system with both positive and negative deviations in To has not yet been reported. For x = 1.0, the system represents the binary system 0.25NaSCN + 0.75CH3CONH2 with To = 210.1 K, which is in reasonable agreement with T, = 234 K (14) reported for the system 0.225NaSCN + 0.775CH3CONH2. The observed variation of To, A, and B with x ( Fig.…”

Section: Resultssupporting

confidence: 76%

“…3 it is apparent that the nature of the variation of K with x varies with temperature. There is no clear transition, such as that reported in the Arrhenius plot of viscosity for the 0.225NaSCN + 0.775CH3CONH, binary system (14). On the contrary, the K VS. x isotherms of the 0.…”

Section: I Mol T R a C T I O Nmentioning

confidence: 75%

“…Similarly Na/KN03 -hydrate melt (16), -water (9), and -glycerol (8) systems also exhibit negative deviation in K VS. x isotherms, and the anion polarization model (APM) (17,18) has been used to explain the MAE on the electrical conductivity. Berchiesi et al (14) suggested that the transition at ca. 293 K in the Arrhenius plot of the viscosity inay be due to a change in liquid structure.…”

Section: I Mol T R a C T I O Nmentioning

confidence: 99%

“…As the system has an inherent tendency to supercool (14), the temperature dependence of the molar volume may also be represented as…”

Section: I Mol T R a C T I O Nmentioning

confidence: 99%

“…Molten acetamide is a good nonaqueous solvent for many inorganic salts due to its dipolar nature (13), and molten acetamide-electrolyte binary systems have a tendency to form supercooled liquid (14). It has been reported that Na' ion forms a polymeric type of solvated ion of low ionic mobility with acetamide (15).…”

Section: Introductionmentioning

confidence: 99%

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Mixed alkali effect in sodium thiocyanate–potassium thiocyanate – acetamide melt systems

Mahiuddin¹

1996

Can. J. Chem.

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Electrical conductivity and molar volume of the 0.25[xNaSCN + (1 -x)KSCN] + 0.75CH3CONH, systems were measured as functions of temperature (~293.15-358.15 K) and composition (x = 0.0 -1 . O mol fraction). Temperature dependence of the electrical conductivity was non-Arrhenius in nature and has been analysed by using the Vogel-TammannFulcher (VTF) equation. Molar volume data were fitted to an equation similar to the VTF equation based on the free volume model. Molar volumes and intrinsic volumes were found to be additive in nature. Electrical conductivity isotherms deviate from linearity in different fashion for different temperature regions. The onset of the mixed alkali effect is governed by the anion polarization effect, by a contribution of the auto-dissociated molten acetamide, and by polymeric-type solvated ions.

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Section: Resultssupporting

confidence: 76%

Section: I Mol T R a C T I O Nmentioning

confidence: 75%

Section: I Mol T R a C T I O Nmentioning

confidence: 99%

“…As the system has an inherent tendency to supercool (14), the temperature dependence of the molar volume may also be represented as…”

Section: I Mol T R a C T I O Nmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mixed alkali effect in sodium thiocyanate–potassium thiocyanate – acetamide melt systems

Mahiuddin¹

1996

Can. J. Chem.

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Acetamide-ammonium sulfamate

Castellani

Berchiesi

Bartocci

1990

Journal of Thermal Analysis

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Molten mixtures of acetamide and ammonium sulfamate (indicated here AS) are reacted at mole fraction XAs < 0.35 to produce (NH4)2SO4 and CH3CN. The experimental conditions and analytical methods adopted are given and a kinetic mechanism is proposed.For several years we have been studying the particular properties of molten mixtures of amides and electrolytes [1][2][3][4][5][6][7][8][9][10]. In some cases they show polymeric structures which are reponsible for supercooling phenomena and for a very high dielectric constant [11][12][13][14][15]. With the aim of clarifying the chemical conditions where this type of phenomena oeeurs, we studied the liquid-solid equilibrium temperatures, in binary mixtures, amide + electrolytes; of these systems the acetamide + ammonium sulfamate mixture showed reactive properties. ExperimentalThe cryoscopic method employed is reported elsewhere [16]: it consists of a potentiometrie measurements of temperature (via a ehromel-alumel thermocouple, calibrated against a Pt thermometer). NMR measurements were performed by means of a Varian XL-300. The chemicals employed were: acetamide Fluka AG, Buchs SG purum ammonium sulfamate Fisher Scientific Company certified. They were dried under dynamic vacuum for several days before use.

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Supercooling phenomena in the binary systems: Acetamide-electrolytes

Berchiesi

Lobbia

Berchiesi

et al. 1984

Journal of Thermal Analysis

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This paper presents a final discussion on studies of solutions of electrolytes in molten acetamide. These studies deal with cryoscopic and ultrasonic (by shear waves) techniques and reveal the complexity of the behaviour of these systems due to strong ion-solvent interactions.Acetamide is considered a good solvent for electrolytes and is often empolyed in electrochemistry as a non-aqueous solvent [1][2][3][4][5]. This fact and the similarity of some its physical properties (e.g. dielectric constant or ionization constant) with the corresponding values of water tend to induce the belief that solutions in acetamide are similar in structure to the corresponding solutions in water.This paper and previous ones [6-9] may give a clearer idea of the complexity of these non-aqueous mixtures.The methods employed were reported in previous papers [6, 10, 11], and are not given here. Discussion CryoscopyLiquid-solid equilibria in the binary systems acetamide + electrolytes [7][8][9] present differences in behaviour, depending on the types of the ions..Two classes may be distinguished:1) The anion is CIO4, NO~-or CNS-(derived from strong acids) and the cation is an alkali metal or an alkaline earth metal.2) The anion is CH3COO-or HCOO-(derived from weak acids) and the cation is an alkali metal.In general, the temperature Teut in the first class is lower than Teu t in the second class. That is, the solubility of a salt of the first class is higher in acetamide. SchematiThermalAnaL 29, 1984

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Viscoelastic relaxation in the acetamide + sodium thiocyanate binary system

Cited by 43 publications

References 0 publications

Mixed alkali effect in sodium thiocyanate–potassium thiocyanate – acetamide melt systems

Mixed alkali effect in sodium thiocyanate–potassium thiocyanate – acetamide melt systems

Acetamide-ammonium sulfamate

Supercooling phenomena in the binary systems: Acetamide-electrolytes

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