Effect of a magnetic field on the rheological properties of the systems hydroxypropyl cellulose–ethanol and hydroxypropyl cellulose–dimethyl sulfoxide

With the use of viscometry, the cloud-point method, polarization microscopy, the turbidity-spectrum method, and a polarization photoelectric apparatus, the relaxation pattern of the rheological behaviors, phase transitions, and structures of the systems hydroxypropyl cellulose–ethanol and hydroxypropyl cellulose–dimethyl sulfoxide are studied. The regions of existence of isotropic and anisotropic phases and the concentration dependence of the sizes of supramolecular particles are determined. It is found that a magnetic field increases the viscosities of solutions. The concentration dependences of viscosity and particle size are described by curves with maxima.     

Enthalpy of mixing in the propylene oxide–dimethylformamide and propylene oxide–ethylene glycol systems

Heat of mixing of propylene oxide with N,N-dimethylformamide and ethylene glycol has been determined by means of microcalorimetry. Theoretically suggested choice of the aprotic solvent as a selective separating agent for the propylene oxide–methanol binary mixture has been experimentally justified.     

Experimental study on rheological behavior of water–ethylene glycol mixture in the presence of functionalized multi-walled carbon nanotubes

Journal of Thermal Analysis and Calorimetry - This paper examines the rheological behavior of water (60%vol.)–ethylene glycol (40%vol.) mixture in the presence of functionalized multi-walled...     

Thermo-physical properties of pure ethylene glycol and water–ethylene glycol mixture-based boron nitride nanofluids

Journal of Thermal Analysis and Calorimetry - Nanofluids are suspensions of solid nanoparticles in conventional heat transfer fluids, and they often exhibit improved heat transfer characteristics....     

Phase equilibrium in the ternary system water–ethylene glycol–dimethyl sulfoxide

The ternary system water–ethylene glycol–dimethyl sulfoxide (H₂O–EG–DMSO) was investigated by differential scanning calorimetry in the temperature range of 188–298 K. In the concentration range from ∼10 to ∼50 mol% DMSO, crystallization or glass formation are not observed when the temperature is lowered to 188 K. Significant supercooling of the solution in this composition range is explained by the existence of spatial networks of H₂O and EG.     

Phase equilibria and structures of phases in the chitosan—polyvinyl alcohol systems

Russian Chemical Bulletin - Phase equilibria in the mixtures of polyvinyl alcohol (PVA) and chitosan were revealed. Structures of the phases were identified. The temperature and concentration...     

Phase composition,physicochemical and catalytic properties of cobalt–aluminum–zeolite systems

The phase composition and physicochemical and catalytic properties of three samples of cobalt–aluminum–zeolite systems were studied. The catalytic properties of the systems are related to the application of a highly porous acidic support and the presence of cobalt oxide crystallites of an optimal size (6–12 nm). The occurrence of an efficient heat-conductive spatial net formed by metallic aluminum particles is also important for catalytic performance.     

Using artificial neural networks to predict the rheological behavior of non-Newtonian graphene–ethylene glycol nanofluid

Journal of Thermal Analysis and Calorimetry - The ability of the artificial neural network (ANN) to predict the viscosity of graphene nanosheet/ethylene glycol ( $$\mu_{{\text{Gr/EG}}}$$ ) was...     

Characterization of a heavy oil–propane system in the presence or absence of asphaltene precipitation

When a light hydrocarbon solvent is injected into a heavy oil reservoir under a sufficiently high reservoir pressure, asphaltene precipitation occurs so that the heavy oil is in situ deasphalted during a hydrocarbon solvent-based heavy oil recovery process. The physicochemical properties of this in situ deasphalted heavy oil are rather different from those of the original crude oil in the heavy oil reservoir. In this paper, a heavy oil sample is saturated with a typical light hydrocarbon solvent (i.e., propane) under different saturation pressures in a see-through windowed high-pressure saturation cell. The heavy oil–propane system is characterized by measuring and comparing several important physicochemical properties of the propane-saturated heavy oil samples under different saturation pressures and the flashed-off heavy oil samples, such as the solubility, oil-swelling factor, density, viscosity, asphaltene content, hydrogen and carbon aromaticities. When the heavy oil is saturated with propane at P ≤ 780 kPa and T = 20.8 °C, there is no observable asphaltene precipitation and deposition under a microscope camera. The respective properties of the propane-saturated heavy oil samples taken from the upper and lower parts of the saturation cell are measured and found to be essentially the same within the experimental errors so that the entire system is considered to be almost homogeneous. If the saturation pressure is increased to P = 850 kPa, strong asphaltene precipitation occurs and some large asphaltene particles are deposited onto the bottom of the saturation cell. In this case, the heavy oil is deasphalted and the flashed-off heavy oil has lower density, viscosity, asphaltene content, hydrogen and carbon aromaticities than those of the original heavy crude oil.     

The experimental investigation concerning the heat transfer enhancement via a four-point star swirl generator in the presence of water–ethylene glycol mixtures

Journal of Thermal Analysis and Calorimetry - In the present study, a new swirling flow generator is studied which aims to enhance the convective heat transfer rate in a heat exchanger tube. This...     

Solvent-dependent structures of lanthanide–TCNQ coordination networks and their magnetic properties

Abstract

Lanthanide complexes were prepared with 2,6-diacetylpyridinebis(benzoylhydrazone) (DAPBH₂) and 7,7,8,8-tetracyano-p-quinodimethanide (TCNQ^??). The complexes adopted one of two structure types depending on the reaction solvent. The complexes were categorized as Type I (i.e. bis{[2,6-diacetylpyridinebis(benzoylhydrazone)] methanollanthanide(III)}bis(µ₂- 7,7,8,8-tetracyanoquinodimethanide(1?))bis(7,7,8,8-tetracyanoquinodimethanide(1?))bis(7,7,8,8-tetracyanoquinodimethanide(1?)) methanol disolvate, [Ln₂(DAPBH₂)₂ (µ₂-TCNQ^??)₂(TCNQ^??)₂(MeOH)₂](TCNQ^??)₂·2MeOH (Ln?=?Gd, Tb, or Dy) or Type-II (i.e. [Ln₂(DAPBH₂)₂(µ₂-TCNQ^??)₂(TCNQ^??)₂(EtOH)₂] (TCNQ^??)₂·solvent (Ln?=?Tb and Dy, solvent =4EtOH for the Tb and 2EtOH·2CH₂Cl₂ for the Dy complexes). These two complexes exhibit dramatically different molecular structures and packings. In all complexes, the strong intra- and intermolecular stacking interactions of the TCNQ^?? radicals lead to the formation of 1D TCNQ chains. Magnetic susceptibility measurements for Type I and Type II complexes reveal that they exhibit paramagnetic behavior and that their magnetic properties originate from the lanthanide ions alone, owing to the diamagnetic nature of the TCNQ^?? stacks.     

First principles study of the electronic and magnetic structures and bonding properties of UCoC2 ternary,characteristic of C–C units

The electronic structure of UCoC₂, a di-carbide with the C–C units is examined from ab initio with an assessment of the properties of chemical bonding. The energy–volume equation of state shows large anisotropy effects due to C–C alignment along tetragonal c-axis leading to high linear incompressibility. Relevant features of selective bonding of uranium and cobalt with carbon at two different Wyckoff sites and strong C–C interactions are remarkable. The vibrational frequencies for C⋯C stretching modes indicate closer behavior to aliphatic C–C rather than CC double bond. A ferromagnetic ground state is proposed from the calculations.     

Supramolecular engineering of a 2D Kagomé lattice: synthesis, structures, and magnetic properties

Two 2D Mn (II) complexes, [Mn3(TzDC)2(phen)3] x 2 H2O (1; H3TzDC = 1,2,3-triazole-4,5-dicarboxylic acid, phen = 1,10-phenanthroline) and [Mn3(TzDC)2(bipy)3] x 4 H2O (2; bipy = 2,2'-bipyridine), were synthesized by hydrothermal reactions and characterized magnetically, and complex 1 was the first example of the chiral complex with a Kagomé lattice connectivity obtained through spontaneous resolution.     

Investigation of the thermal properties of glycidyl methacrylate–ethylene glycol dimethacrylate copolymeric microspheres modified by Diels–Alder reaction

Journal of Thermal Analysis and Calorimetry - The study describes the thermal properties of functional microspheres composed of glycidyl methacrylate (GMA) and crosslinking agent ethylene glycol...     

Thermomechanical,calorimetric and magnetic properties of a Ni–Ti shape-memory alloy wire

Journal of Thermal Analysis and Calorimetry - In this work, some physical properties of a commercial Ni–Ti (nitinol) shape-memory alloy with cylindrical geometry (wire) were investigated; the...     

Phase equilibrium in aqueous two-phase systems containing ethylene oxide–propylene oxide block copolymers and dextran

Phase equilibrium of aqueous two-phase systems containing the polysaccharide dextran and ethylene oxide (EO)/propylene oxide (PO) triblock copolymers was investigated in this work. Phase diagrams at 25.0 °C were experimentally obtained for systems formed by either dextran 19 (average molar mass of 8200 g mol⁻¹) or dextran 400 (average molar mass of 236 kg mol⁻¹) and one of the following block copolymers F38, F68, F108, P105 and P103, which present different structures in terms of EO/PO ratios and molar masses. It was possible to assess the influence of the polymer features on the phase equilibrium: the main factors affecting phase equilibrium being the size of dextran molecule and the structure (mainly the EO/PO ratio) of the copolymer. The Flory–Huggins equation was used to correlate the experimental data with good qualitative agreement, allowing the inference that changes in the copolymer hydrophobicity are the main responsible for the observed phase diagrams.