The complex relative dielectric function, dielectric loss tangent, electric modulus, alternating ... more The complex relative dielectric function, dielectric loss tangent, electric modulus, alternating current electrical conductivity and impedance spectra of ethylene glycol oligomers (EGOs) i.e., ethylene glycol, diethylene glycol and poly(ethylene glycol)s of average molecular weight 200, 300, 400 and 600 g mol-1 have been investigated in the frequency range 20 Hz to 1 MHz at 25 °C. These EGOs show the low frequency dielectric/electrical dispersion due to electrode polarization and ionic conduction effects. The ‘master curves representation’ of the real and imaginary parts of the intensive dielectric/electrical functions were used to evaluate the relaxation times corresponding to these effects processes. The comparative dielectric study of EGOs confirms that the values of low frequency relaxation times and direct current electrical conductivity are influenced by the chain flexibility and its random coiling.
Colloids and Surfaces A-physicochemical and Engineering Aspects, 2009
Frequency-dependent complex dielectric function, loss tangent, electric modulus, alternating curr... more Frequency-dependent complex dielectric function, loss tangent, electric modulus, alternating current electrical conductivity, and impedance spectra of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG), and blends of PVA-PVP and PVA-PEG, loaded with polymer grade montmorillonite (MMT) clay upto 5 wt% of solute (polymer + clay) in aqueous colloidal suspensions, have been investigated in the frequency range 20 Hz to 1 MHz at 27 • C. These materials show the dielectric dispersion corresponding to ionic conduction and electrode polarization phenomena in the experimental frequency range. The loss tangent peak frequency which separates the contribution of the bulk material and the electrode polarization phenomenon was used to evaluate the electrode polarization relaxation time corresponding to the dynamics of electric double layers. The dielectric and electrical conductivity spectra were interpreted as a result of these material complex structures formed by constituents H-bonding interactions, and the clay intercalation and exfoliation that alter the conduction pathways. Results show that the dielectric/electrical properties of the polymer-clay nanocomposites aqueous colloidal suspension have good resemblance to their structural properties, which were explored from other spectroscopic and morphological techniques. A close look on the dielectric parameters of the investigated materials proves the suitability for the synthesis of new materials with desirable and predicted properties.
The formation of hydrogen bonds between different types of molecules in binary alcohol mixtures (... more The formation of hydrogen bonds between different types of molecules in binary alcohol mixtures (methyl alcohol, ethyl alcohol, ethylene glycol, propylene glycol and glycerol) have been investigated (each system at 21 mixture concentrations) by an analysis of their dielectric parameters. The static dielectric constant ε o, limiting high-frequency dielectric constant ε ∞, excess dielectric parameters ε oE and ε ∞E, effective Kirkwood correlation factor g eff, and corrective Kirkwood correlation factor g f of the binary alcohol mixtures were determined at 25 °C in order to explore hydrogen-bond interactions and the strength of molecular connectivities between unlike alcohol molecules and their dipole alignment. These results confirm that the different alcohol mixtures form hydrogen-bonded structures, which are strongly influenced by the numbers of hydroxyl groups and carbon atoms of the alcohol molecules and vary with the concentrations of the mixtures.
The complex dielectric constant 3 Ã ðuÞ ¼ 3 0 À j3 00 , electric modulus M Ã ðuÞ ¼ M 0 þ jM 00 , ... more The complex dielectric constant 3 Ã ðuÞ ¼ 3 0 À j3 00 , electric modulus M Ã ðuÞ ¼ M 0 þ jM 00 , impedance Z Ã ðuÞ ¼ Z 0 À jZ 00 and ac conductivity dispersion behaviour of 5, 10 and 15 wt% concentration aqueous solutions of poly(vinyl alcohol) (PVA) (14 000 and 77 000 g mol À1 ) and poly-(vinyl pyrrolidone) (PVP) (24 000, 40 000 and 360 000 g mol À1 ) and their binary mixtures were investigated in the frequency range 20 Hz to 1 MHz at 25 C. Analysis of dielectric constant values confirms that hydrophilic effect of PVA in aqueous solution increases the real part of dielectric constant 3 0 , whereas for aqueous PVP solutions the hydrophobic effect masks the hydrophilic effect, which reduces 3 0 values below 10 kHz. Low-frequency dielectric constant of these aqueous polymeric systems is sensitive to ionic conduction and electrode polarization. The monotonous change in various electrical properties with change in volume percentage of mixture constituents indicates that individual aqueous polymer system retains their own electrical properties in the aqueous two-phase polymeric system.
The hydrogen-bond molecular interactions and molar ratio of stable adduct in binary mixtures of N... more The hydrogen-bond molecular interactions and molar ratio of stable adduct in binary mixtures of N,N-dimethylethanolamine with alcohols (ethyl alcohol, ethylene glycol, glycerol) and amides (formamide, N,N-dimethylformamide, N,N-dimethylacetamide) have been investigated over the entire concentration range at 30°C by dielectric measurements. The effect of molecular size, number of hydroxyl groups of alcohols molecules and the extent of substitution in amide molecules
The dielectric constant of binary mixtures of formamide with some common dipolar aprotic and prot... more The dielectric constant of binary mixtures of formamide with some common dipolar aprotic and protic solvents has been investigated at sixteen molar concentrations over the entire mixing range at 30 °C. The solvents used for binary mixtures with formamide are water, dimethylsulphoxide, N,N-dimethylformamide, acetone, 1,4-dioxane, mono-, di- and trihydric alcohols, and homologous series of 2-alkoxyethanol, 2-(2-alkoxyethoxy)ethanol, and ethylene glycol oligomers. The
The complex relative dielectric function $ \varepsilon *{\left( \omega \right)} = \varepsilon \pr... more The complex relative dielectric function $ \varepsilon *{\left( \omega \right)} = \varepsilon \prime - j\varepsilon \prime \prime $ , loss tangent $ \tan \delta = {\varepsilon \prime \prime } \mathord{\left/ {\vphantom {{\varepsilon \prime \prime } {\varepsilon \prime }}} \right. \kern-0em} {\varepsilon \prime } $ , complex electric modulus $ M*{\left( \omega \right)} = M\prime + jM\prime \prime $ and alternating current electrical conductivity dispersion behaviour of liquid poly(vinyl pyrrolidone)-poly(ethylene glycol) (PVP–PEG) blends in water, ethyl alcohol and 1,4–dioxane solvent over the entire volume mixture concentration range has been investigated in the frequency range of 20 Hz to 1 MHz at 25 °C. The PVP–PEG blends show the dielectric dispersion corresponding to the micro-Brownian motion of the PVP chain in the upper frequency region, whereas in the lower frequency region, dielectric dispersion is due to ionic conduction and electrode polarization phenomena. Results show that the conductivity values of these blends in water and dioxane can be monitored with the change in the solvent concentration, whereas it has a small variation with ethyl alcohol concentration. The comparative dielectric dispersion shape study confirms that the chain dynamics of polymers blend is influenced by heterogeneous interactions and solvent polar strength.
Polymer nanocomposite electrolytes (PNCEs) of poly(ethylene oxide) and sodium perchlorate monohyd... more Polymer nanocomposite electrolytes (PNCEs) of poly(ethylene oxide) and sodium perchlorate monohydrate complexes with montmorillonite (MMT) clay up to 20 wt.% MMT concentration of poly(ethylene oxide) (PEO) are synthesized by melt compounding technique at melting temperature of PEO (∼70 °C) and NaClO4 monohydrate (∼140 °C). Complex dielectric function, electric modulus, alternating current (ac) electrical conductivity, and impedance properties of these PNCEs films are investigated in the frequency range 20 Hz to 1 MHz at ambient temperature. The direct current conductivity of these materials was determined by fitting the frequency-dependent ac conductivity spectra to the Jonscher power law. The PNCEs films synthesized at melting temperature of NaClO4 monohydrate have conductivity values lower than that of synthesized at PEO melting temperature. The complex impedance plane plots of these PNCEs films have a semicircular arc in upper frequency region corresponding to the bulk material properties and are followed by a spike in the lower frequency range owing to the electrode polarization phenomena. Relaxation times of electrode polarization and ionic conduction relaxation processes are determined from the frequency values corresponding to peaks in loss tangent and electric modulus loss spectra, respectively. A correlation is observed between the ionic conductivity and dielectric relaxation processes in the investigated PNCEs materials of varying MMT clay concentration. The scaled ac conductivity spectra of these PNCEs materials also obey the ac universality law.
... solute solutions for the confirmation of watersolute interactions and their molecular dynami... more ... solute solutions for the confirmation of watersolute interactions and their molecular dynamics. ... In solutewater mixture, the H-bonds form the homogeneous and heterogeneous cooperative domain ... constant ε o of the studied molecules and their binary mixtures were determined ...
Influence of polar solvents environment and polymer concentrations on the electrical properties (... more Influence of polar solvents environment and polymer concentrations on the electrical properties (complex dielectric constant, ac electrical conductivity, complex electric modulus and complex impedance) of the solutions of poly(vinyl pyrrolidone) (PVP) in polar solvents, namely water, ethyl alcohol, ethylene glycol, diethylene glycol, poly(ethylene glycol), glycerol, dimethyl sulfoxide and dimethyl formamide, have been investigated in the frequency range 20 Hz–1 MHz at 25°C. Comparative analysis of the dielectric dispersion curves confirms that the solvent molecular size and number of its hydroxyl groups, and the solutions viscosity, are the major factors which governs the PVP chain segmental motion. The ionic conduction and electrode polarization phenomena has a dominant influence on the large increase of complex dielectric constant values of the solutions of PVP‐polar solvent in the lower frequency region. The values of relaxation times corresponding to these phenomena are also reported.
The heterogeneous H-bonded interactions in mixtures of glass-former liquids, i.e., binary mixture... more The heterogeneous H-bonded interactions in mixtures of glass-former liquids, i.e., binary mixtures of ethyl alcohol (EA) with ethylene glycol (EG) and ternary mixtures of equi-molar EA + EG system with glycerol (Gly) have been investigated at 21 concentrations by using precisely measured values of static and high frequency limiting dielectric constants at 25°C. Concentration dependent observed negative values of excess dielectric constant (e E ) and effective Kirkwood correlation factor (g eff ) implies the formation of H-bonded complexes between EA and EG molecules which reduces the effective number of dipoles. The EA + EG system forms the strongest complexes corresponding to the molar ratio $1:1. The observed positive e E values of the (EA + EG) + Gly ternary mixtures confirm the increase in number of effective dipoles contributed to the dielectric constant values due to the formation of the ternary complexes. Critical analysis of the experimental results of the EA + EG and the (EA + EG) + Gly mixtures suggest the suitability of e E and g eff study in order to explain the dipolar ordering mechanism formed during the complexes between the alcohol molecules in their ternary mixtures.
ABSTRACT The static dielectric constants of binary mixtures of N-methylformamide (NMF), used as a... more ABSTRACT The static dielectric constants of binary mixtures of N-methylformamide (NMF), used as a solute with the solvents water (W), ethyl alcohol (EA), ethylene glycol (EG), dimethyl sulphoxide (DMSO), acetone (Ac) and 1,4-dioxane (Dx), have been measured over the entire concentration range at 30°C. The negative values of excess dielectric constant and less-than-unity values of the corrective Kirkwood correlation factor of these binary mixtures are used to analyse the formation of H-bond complexes and molar ratio of the stable adduct. In these systems, the unassociated mixture constituents, DMSO, Ac and Dx, act as structure-breakers for self-associated linear structures of NMF, whereas, both the self-associated mixture constituents (W, EA and EG mixtures with NMF) act as structure-breakers to each other during the complexations. It is found that the large variations in the strength of H-bond complexation and the effective number of parallel aligned dipoles in the mixtures are governed by the dielectric constant of the solvents.
Hydrogen bond molecular interactions and dipolar ordering in binary mixtures of amides (N-methylf... more Hydrogen bond molecular interactions and dipolar ordering in binary mixtures of amides (N-methylformamide (NMF), formamide (FA), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA)) with dimethylsulphoxide (DMSO) and 1,4-dioxane (Dx) have been investigated by dielectric measurements at 30°C. The static dielectric constant, high frequency limit dielectric constant, excess dielectric constant, effective Kirkwood correlation factor, and corrective Kirkwood correlation factor of the binary mixtures over the entire concentration range were determined to explore the effect of substituted and unsubstituted amides on hetero-molecular interactions. Results confirm that the unlike molecule hydrogen bond interaction strength is comparatively 1.5 times stronger in amides-Dx mixtures as compared to the amides-DMSO mixtures, which vary linearly with the values of dielectric constant and Kirkwood correlation factor of pure amides. Dielectric studies inferred 2:1 complexation of NMF to DMSO/Dx, whereas other amides-DMSO and amides-Dx mixed solvents form most likely 1:1 complexes.
The relative complex dielectric function, electric modulus, alternating current (ac) electrical c... more The relative complex dielectric function, electric modulus, alternating current (ac) electrical conductivity and complex impedance spectra of poly(ethylene oxide) (PEO)–montmorillonite (MMT) clay aqueous colloidal suspension (hydrocolloids) were investigated over the frequency range 20 Hz to 1 MHz at 27 °C. The relaxation time corresponding to electrode polarisation and Maxwell–Wagner polarisation processes (ionic conduction) were determined from these plots. The direct current (dc) electrical conductivity is evaluated from the fitting of real part ac conductivity data to the Jonscher power law. A correlation of increase in dc conductivity and decrease of ionic conduction relaxation time with increase of clay concentration is discussed considering intercalation of PEO chains and its dynamics and exfoliation of MMT clay nanoplatelets in these complex fluids. The formation of PEO–MMT clay supramolecular lamellar nanostructures with increase in continuity of lamellae arrangements were explored for the structural conformation of these nanocomposite novel materials.
ABSTRACT The dielectric constant of binary mixtures of formamide with some common dipolar aprotic... more ABSTRACT The dielectric constant of binary mixtures of formamide with some common dipolar aprotic and protic solvents has been investigated at sixteen molar concentrations over the entire mixing range at 30 °C. The solvents used for binary mixtures with formamide are water, dimethylsulphoxide, N,N-dimethylformamide, acetone, 1,4-dioxane, mono-, di- and trihydric alcohols, and homologous series of 2-alkoxyethanol, 2-(2-alkoxyethoxy)ethanol, and ethylene glycol oligomers. The concentration dependent plots of excess dielectric constant and Kirkwood correlation factor were used to explore the complexes formed between unlike molecules, the molar ratio of a stable adduct, dipolar ordering, hydrogen-bond molecular connectivities, and their strength in the binary mixtures. Results confirmed that the complexation strength of dipolar aprotic solvents with formamide strongly depends on the value of solvent dielectric constant. The dependence of the hydrogen-bond complexation on number of hydroxyl groups and molecular size of the homologous series of the solvents is recognized from the comparative excess dielectric constant values of the mixed solvents.
The concentration dependent static dielectric constant, high frequency limit dielectric constant,... more The concentration dependent static dielectric constant, high frequency limit dielectric constant, excess dielectric constant and the effective Kirkwood correlation factor of the binary mixtures of glycerol with formamide, N,N-dimethylformamide, N,N-dimethylacetamide, ethanolamine and N,N-dimethylaminoethanol have been determined at 30°C. The values of these functions emphasize mainly on the hydrogen bonding interactions between the unlike molecules in glycerol-amides and glycerol-amines mixtures, in
The complex relative dielectric function, dielectric loss tangent, electric modulus, alternating ... more The complex relative dielectric function, dielectric loss tangent, electric modulus, alternating current electrical conductivity and impedance spectra of ethylene glycol oligomers (EGOs) i.e., ethylene glycol, diethylene glycol and poly(ethylene glycol)s of average molecular weight 200, 300, 400 and 600 g mol-1 have been investigated in the frequency range 20 Hz to 1 MHz at 25 °C. These EGOs show the low frequency dielectric/electrical dispersion due to electrode polarization and ionic conduction effects. The ‘master curves representation’ of the real and imaginary parts of the intensive dielectric/electrical functions were used to evaluate the relaxation times corresponding to these effects processes. The comparative dielectric study of EGOs confirms that the values of low frequency relaxation times and direct current electrical conductivity are influenced by the chain flexibility and its random coiling.
Colloids and Surfaces A-physicochemical and Engineering Aspects, 2009
Frequency-dependent complex dielectric function, loss tangent, electric modulus, alternating curr... more Frequency-dependent complex dielectric function, loss tangent, electric modulus, alternating current electrical conductivity, and impedance spectra of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG), and blends of PVA-PVP and PVA-PEG, loaded with polymer grade montmorillonite (MMT) clay upto 5 wt% of solute (polymer + clay) in aqueous colloidal suspensions, have been investigated in the frequency range 20 Hz to 1 MHz at 27 • C. These materials show the dielectric dispersion corresponding to ionic conduction and electrode polarization phenomena in the experimental frequency range. The loss tangent peak frequency which separates the contribution of the bulk material and the electrode polarization phenomenon was used to evaluate the electrode polarization relaxation time corresponding to the dynamics of electric double layers. The dielectric and electrical conductivity spectra were interpreted as a result of these material complex structures formed by constituents H-bonding interactions, and the clay intercalation and exfoliation that alter the conduction pathways. Results show that the dielectric/electrical properties of the polymer-clay nanocomposites aqueous colloidal suspension have good resemblance to their structural properties, which were explored from other spectroscopic and morphological techniques. A close look on the dielectric parameters of the investigated materials proves the suitability for the synthesis of new materials with desirable and predicted properties.
The formation of hydrogen bonds between different types of molecules in binary alcohol mixtures (... more The formation of hydrogen bonds between different types of molecules in binary alcohol mixtures (methyl alcohol, ethyl alcohol, ethylene glycol, propylene glycol and glycerol) have been investigated (each system at 21 mixture concentrations) by an analysis of their dielectric parameters. The static dielectric constant ε o, limiting high-frequency dielectric constant ε ∞, excess dielectric parameters ε oE and ε ∞E, effective Kirkwood correlation factor g eff, and corrective Kirkwood correlation factor g f of the binary alcohol mixtures were determined at 25 °C in order to explore hydrogen-bond interactions and the strength of molecular connectivities between unlike alcohol molecules and their dipole alignment. These results confirm that the different alcohol mixtures form hydrogen-bonded structures, which are strongly influenced by the numbers of hydroxyl groups and carbon atoms of the alcohol molecules and vary with the concentrations of the mixtures.
The complex dielectric constant 3 Ã ðuÞ ¼ 3 0 À j3 00 , electric modulus M Ã ðuÞ ¼ M 0 þ jM 00 , ... more The complex dielectric constant 3 Ã ðuÞ ¼ 3 0 À j3 00 , electric modulus M Ã ðuÞ ¼ M 0 þ jM 00 , impedance Z Ã ðuÞ ¼ Z 0 À jZ 00 and ac conductivity dispersion behaviour of 5, 10 and 15 wt% concentration aqueous solutions of poly(vinyl alcohol) (PVA) (14 000 and 77 000 g mol À1 ) and poly-(vinyl pyrrolidone) (PVP) (24 000, 40 000 and 360 000 g mol À1 ) and their binary mixtures were investigated in the frequency range 20 Hz to 1 MHz at 25 C. Analysis of dielectric constant values confirms that hydrophilic effect of PVA in aqueous solution increases the real part of dielectric constant 3 0 , whereas for aqueous PVP solutions the hydrophobic effect masks the hydrophilic effect, which reduces 3 0 values below 10 kHz. Low-frequency dielectric constant of these aqueous polymeric systems is sensitive to ionic conduction and electrode polarization. The monotonous change in various electrical properties with change in volume percentage of mixture constituents indicates that individual aqueous polymer system retains their own electrical properties in the aqueous two-phase polymeric system.
The hydrogen-bond molecular interactions and molar ratio of stable adduct in binary mixtures of N... more The hydrogen-bond molecular interactions and molar ratio of stable adduct in binary mixtures of N,N-dimethylethanolamine with alcohols (ethyl alcohol, ethylene glycol, glycerol) and amides (formamide, N,N-dimethylformamide, N,N-dimethylacetamide) have been investigated over the entire concentration range at 30°C by dielectric measurements. The effect of molecular size, number of hydroxyl groups of alcohols molecules and the extent of substitution in amide molecules
The dielectric constant of binary mixtures of formamide with some common dipolar aprotic and prot... more The dielectric constant of binary mixtures of formamide with some common dipolar aprotic and protic solvents has been investigated at sixteen molar concentrations over the entire mixing range at 30 °C. The solvents used for binary mixtures with formamide are water, dimethylsulphoxide, N,N-dimethylformamide, acetone, 1,4-dioxane, mono-, di- and trihydric alcohols, and homologous series of 2-alkoxyethanol, 2-(2-alkoxyethoxy)ethanol, and ethylene glycol oligomers. The
The complex relative dielectric function $ \varepsilon *{\left( \omega \right)} = \varepsilon \pr... more The complex relative dielectric function $ \varepsilon *{\left( \omega \right)} = \varepsilon \prime - j\varepsilon \prime \prime $ , loss tangent $ \tan \delta = {\varepsilon \prime \prime } \mathord{\left/ {\vphantom {{\varepsilon \prime \prime } {\varepsilon \prime }}} \right. \kern-0em} {\varepsilon \prime } $ , complex electric modulus $ M*{\left( \omega \right)} = M\prime + jM\prime \prime $ and alternating current electrical conductivity dispersion behaviour of liquid poly(vinyl pyrrolidone)-poly(ethylene glycol) (PVP–PEG) blends in water, ethyl alcohol and 1,4–dioxane solvent over the entire volume mixture concentration range has been investigated in the frequency range of 20 Hz to 1 MHz at 25 °C. The PVP–PEG blends show the dielectric dispersion corresponding to the micro-Brownian motion of the PVP chain in the upper frequency region, whereas in the lower frequency region, dielectric dispersion is due to ionic conduction and electrode polarization phenomena. Results show that the conductivity values of these blends in water and dioxane can be monitored with the change in the solvent concentration, whereas it has a small variation with ethyl alcohol concentration. The comparative dielectric dispersion shape study confirms that the chain dynamics of polymers blend is influenced by heterogeneous interactions and solvent polar strength.
Polymer nanocomposite electrolytes (PNCEs) of poly(ethylene oxide) and sodium perchlorate monohyd... more Polymer nanocomposite electrolytes (PNCEs) of poly(ethylene oxide) and sodium perchlorate monohydrate complexes with montmorillonite (MMT) clay up to 20 wt.% MMT concentration of poly(ethylene oxide) (PEO) are synthesized by melt compounding technique at melting temperature of PEO (∼70 °C) and NaClO4 monohydrate (∼140 °C). Complex dielectric function, electric modulus, alternating current (ac) electrical conductivity, and impedance properties of these PNCEs films are investigated in the frequency range 20 Hz to 1 MHz at ambient temperature. The direct current conductivity of these materials was determined by fitting the frequency-dependent ac conductivity spectra to the Jonscher power law. The PNCEs films synthesized at melting temperature of NaClO4 monohydrate have conductivity values lower than that of synthesized at PEO melting temperature. The complex impedance plane plots of these PNCEs films have a semicircular arc in upper frequency region corresponding to the bulk material properties and are followed by a spike in the lower frequency range owing to the electrode polarization phenomena. Relaxation times of electrode polarization and ionic conduction relaxation processes are determined from the frequency values corresponding to peaks in loss tangent and electric modulus loss spectra, respectively. A correlation is observed between the ionic conductivity and dielectric relaxation processes in the investigated PNCEs materials of varying MMT clay concentration. The scaled ac conductivity spectra of these PNCEs materials also obey the ac universality law.
... solute solutions for the confirmation of watersolute interactions and their molecular dynami... more ... solute solutions for the confirmation of watersolute interactions and their molecular dynamics. ... In solutewater mixture, the H-bonds form the homogeneous and heterogeneous cooperative domain ... constant ε o of the studied molecules and their binary mixtures were determined ...
Influence of polar solvents environment and polymer concentrations on the electrical properties (... more Influence of polar solvents environment and polymer concentrations on the electrical properties (complex dielectric constant, ac electrical conductivity, complex electric modulus and complex impedance) of the solutions of poly(vinyl pyrrolidone) (PVP) in polar solvents, namely water, ethyl alcohol, ethylene glycol, diethylene glycol, poly(ethylene glycol), glycerol, dimethyl sulfoxide and dimethyl formamide, have been investigated in the frequency range 20 Hz–1 MHz at 25°C. Comparative analysis of the dielectric dispersion curves confirms that the solvent molecular size and number of its hydroxyl groups, and the solutions viscosity, are the major factors which governs the PVP chain segmental motion. The ionic conduction and electrode polarization phenomena has a dominant influence on the large increase of complex dielectric constant values of the solutions of PVP‐polar solvent in the lower frequency region. The values of relaxation times corresponding to these phenomena are also reported.
The heterogeneous H-bonded interactions in mixtures of glass-former liquids, i.e., binary mixture... more The heterogeneous H-bonded interactions in mixtures of glass-former liquids, i.e., binary mixtures of ethyl alcohol (EA) with ethylene glycol (EG) and ternary mixtures of equi-molar EA + EG system with glycerol (Gly) have been investigated at 21 concentrations by using precisely measured values of static and high frequency limiting dielectric constants at 25°C. Concentration dependent observed negative values of excess dielectric constant (e E ) and effective Kirkwood correlation factor (g eff ) implies the formation of H-bonded complexes between EA and EG molecules which reduces the effective number of dipoles. The EA + EG system forms the strongest complexes corresponding to the molar ratio $1:1. The observed positive e E values of the (EA + EG) + Gly ternary mixtures confirm the increase in number of effective dipoles contributed to the dielectric constant values due to the formation of the ternary complexes. Critical analysis of the experimental results of the EA + EG and the (EA + EG) + Gly mixtures suggest the suitability of e E and g eff study in order to explain the dipolar ordering mechanism formed during the complexes between the alcohol molecules in their ternary mixtures.
ABSTRACT The static dielectric constants of binary mixtures of N-methylformamide (NMF), used as a... more ABSTRACT The static dielectric constants of binary mixtures of N-methylformamide (NMF), used as a solute with the solvents water (W), ethyl alcohol (EA), ethylene glycol (EG), dimethyl sulphoxide (DMSO), acetone (Ac) and 1,4-dioxane (Dx), have been measured over the entire concentration range at 30°C. The negative values of excess dielectric constant and less-than-unity values of the corrective Kirkwood correlation factor of these binary mixtures are used to analyse the formation of H-bond complexes and molar ratio of the stable adduct. In these systems, the unassociated mixture constituents, DMSO, Ac and Dx, act as structure-breakers for self-associated linear structures of NMF, whereas, both the self-associated mixture constituents (W, EA and EG mixtures with NMF) act as structure-breakers to each other during the complexations. It is found that the large variations in the strength of H-bond complexation and the effective number of parallel aligned dipoles in the mixtures are governed by the dielectric constant of the solvents.
Hydrogen bond molecular interactions and dipolar ordering in binary mixtures of amides (N-methylf... more Hydrogen bond molecular interactions and dipolar ordering in binary mixtures of amides (N-methylformamide (NMF), formamide (FA), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA)) with dimethylsulphoxide (DMSO) and 1,4-dioxane (Dx) have been investigated by dielectric measurements at 30°C. The static dielectric constant, high frequency limit dielectric constant, excess dielectric constant, effective Kirkwood correlation factor, and corrective Kirkwood correlation factor of the binary mixtures over the entire concentration range were determined to explore the effect of substituted and unsubstituted amides on hetero-molecular interactions. Results confirm that the unlike molecule hydrogen bond interaction strength is comparatively 1.5 times stronger in amides-Dx mixtures as compared to the amides-DMSO mixtures, which vary linearly with the values of dielectric constant and Kirkwood correlation factor of pure amides. Dielectric studies inferred 2:1 complexation of NMF to DMSO/Dx, whereas other amides-DMSO and amides-Dx mixed solvents form most likely 1:1 complexes.
The relative complex dielectric function, electric modulus, alternating current (ac) electrical c... more The relative complex dielectric function, electric modulus, alternating current (ac) electrical conductivity and complex impedance spectra of poly(ethylene oxide) (PEO)–montmorillonite (MMT) clay aqueous colloidal suspension (hydrocolloids) were investigated over the frequency range 20 Hz to 1 MHz at 27 °C. The relaxation time corresponding to electrode polarisation and Maxwell–Wagner polarisation processes (ionic conduction) were determined from these plots. The direct current (dc) electrical conductivity is evaluated from the fitting of real part ac conductivity data to the Jonscher power law. A correlation of increase in dc conductivity and decrease of ionic conduction relaxation time with increase of clay concentration is discussed considering intercalation of PEO chains and its dynamics and exfoliation of MMT clay nanoplatelets in these complex fluids. The formation of PEO–MMT clay supramolecular lamellar nanostructures with increase in continuity of lamellae arrangements were explored for the structural conformation of these nanocomposite novel materials.
ABSTRACT The dielectric constant of binary mixtures of formamide with some common dipolar aprotic... more ABSTRACT The dielectric constant of binary mixtures of formamide with some common dipolar aprotic and protic solvents has been investigated at sixteen molar concentrations over the entire mixing range at 30 °C. The solvents used for binary mixtures with formamide are water, dimethylsulphoxide, N,N-dimethylformamide, acetone, 1,4-dioxane, mono-, di- and trihydric alcohols, and homologous series of 2-alkoxyethanol, 2-(2-alkoxyethoxy)ethanol, and ethylene glycol oligomers. The concentration dependent plots of excess dielectric constant and Kirkwood correlation factor were used to explore the complexes formed between unlike molecules, the molar ratio of a stable adduct, dipolar ordering, hydrogen-bond molecular connectivities, and their strength in the binary mixtures. Results confirmed that the complexation strength of dipolar aprotic solvents with formamide strongly depends on the value of solvent dielectric constant. The dependence of the hydrogen-bond complexation on number of hydroxyl groups and molecular size of the homologous series of the solvents is recognized from the comparative excess dielectric constant values of the mixed solvents.
The concentration dependent static dielectric constant, high frequency limit dielectric constant,... more The concentration dependent static dielectric constant, high frequency limit dielectric constant, excess dielectric constant and the effective Kirkwood correlation factor of the binary mixtures of glycerol with formamide, N,N-dimethylformamide, N,N-dimethylacetamide, ethanolamine and N,N-dimethylaminoethanol have been determined at 30°C. The values of these functions emphasize mainly on the hydrogen bonding interactions between the unlike molecules in glycerol-amides and glycerol-amines mixtures, in
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Papers by Sonu Sankhla