Correlation between clay type and performance of swelling inhibitors based on polyetherdiamine in aqueous fluids

In this work, the linear swelling of four samples of natural clays was evaluated, using poly(propylene glycol) bis(2-aminopropyl ether) ~230 g mol⁻¹ (PEDA-230) and ~400 g mol⁻¹ (PEDA-400) as shale inhibitors for water-based drilling fluids, in comparison to a commercial shale inhibitor. The swelling kinetics was described by a semiempirical equation. A correlation was found between the cation exchange capacity of the clays and the diffusion kinetic constant of the inhibitors. Increased molar mass of PEDA favored swelling inhibition. The swelling inhibition was also evaluated by rheology, and the results were in agreement with the linear swelling tests. Scanning electron microscopy demonstrated the occurrence of microfractures on the clay surface after water contact, as well as the adsorption of the different shale inhibitors on the clay surfaces after contact with the aqueous inhibited fluid. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47661.     

Resin-silica composite nanoparticle grafted polyethylene membranes for lithium ion batteries

To avoid the peeling-off of ceramic nanoparticles (NPs) from polyolefin membranes usually occurred in commercially available ceramic NPs coated polyolefin separators for lithium batteries, we propose a simple one-pot in-situ reaction method to modify commercial polyethylene (PE) separators by surface grafting 3-Aminophenol/formaldehyde (AF)/silica (SiO₂) composite NPs. The AF/SiO₂ composite NPs form self-supporting connected pores on the modified layer of the separator surface, which ensures the transportation of Li⁺. Moreover, the PE@AF/SiO₂ separators has higher electrolyte wettability and compatibility than neat PE separators attributed to the plentiful polar functional groups in the AF/SiO₂ layer and AF/SiO₂ composite NPs, resulting in higher lithium ion transference number (= 0.62) and ionic conductivity (σ = 0.722 mS cm⁻¹). More importantly, the discharge capacity, capacity retention rate and coulombic efficiency (136.2 mA h g⁻¹, 87.9% and 99%, respectively) after 200 cycles of Li|NMC half batteries with PE@AF/SiO₂ separators, are all more excellent than that with the pure PE separator (125 mA h g⁻¹, 83.1% and 85%, respectively). Our results show that the PE@AF/SiO₂ separators obtained by this modification method have higher electrochemical stability in the lithium battery system.     

Synthesis,thermal, dielectric,and microwave reflection loss properties of nickel oxide filler with natural fiber-reinforced polymer composite

Fabrication of hybrid composite of nickel oxide (NiO) combined with oil palm empty fruit bunch (OPEFB) reinforced with polycaprolactone (PCL) has been done by using thermal Haake blending machine, which ensured mixture homogeneity. All hybrid composites' characterizations were carried out using X-ray diffraction (XRD), Fourier transform infrared spectrometry, differential thermogravimetry, thermogravimetric analysis, and scanning electron microscopy. The results showed that the XRD profile patterns of the composites clearly changed as the filler loading amount was increased. Fourier transform infrared spectra illustrated a slight change in the frequencies and positions of the peaks after adding NiO, indicating that some interactions occurred between C=O and O–H or among the fiber, NiO, and PCL. The microwave electromagnetic properties, such as reflection loss (dB), relative complex permittivity (ε_r =–j), and permeability (−j) were calculated at various microwave frequencies in the X-band (8–12 GHz) range. It was observed that the thermal stability, magnetic, and dielectric properties of NiO:OPEFB:PCL composites were modified significantly with NiO addition. This enables the new hybrid composites to be used as engineering materials in the microwave applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46998.     

Synthesis and evaluation of an environment-friendly terpolymer CaCO3 scale inhibitor for oilfield produced water with better salt and temperature resistance

The CaCO₃ deposits exist widely in the petroleum industry, causing severe damage to the equipment and production. In this article, a novel environment-friendly terpolymer scale inhibitor Poly (maleic anhydride - acrylic acid -2- acrylamide -2- methyl propanesulfonic acid) (P(MA-AA-AMPS))-containing carboxylic acid group, sulfonic acid group, and amide group was synthesized. The structure and molecular weight were characterized by FTIR, ¹H-NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca²⁺ concentration, and concentration on the scale inhibition performance of CaCO₃. The results show that when the monomer ratio is 2.0:1.0:0.5 and the dosage is 20 mg L⁻¹, the maximum scale inhibition efficiency is 95.52%. Even when Ca²⁺ concentration exceeds 1200 mg L⁻¹ and temperature reaches 90 °C, the scale inhibition efficiency is still larger than 80%. The results of SEM and XRD show that P(MA-AA-AMPS) interferes with the growth of CaCO₃ crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO₃ crystals, the size of which drops from 20–30 μm to 2–5 μm. The P(MA-AA-AMPS) can transform CaCO₃ from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO₃ scale is well inhibited. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48460.     

Shear rheology and scaling of semiflexible polymers: Effect of polymer-solvent interactions in the semidilute regime

Semiflexible polymers and their assemblies are important in biology as cross-linked networks of semiflexible polymers form a major structural component of tissue and living cells. This research used shear rheology to demonstrate the tuning from worm-like to rod-like conformation in semiflexible polymers by polymer-solvent interactions. The conformation was assessed by the persistence length l_p, and its influence, in the semidilute regime, was assessed by the scaling of zero-shear viscosity η_o with concentration c and molecular weight . The polymers were poly n-butyl and poly n-octyl isocyanate (PBIC and POIC, respectively). PBIC exhibited the largest l_p in chlorinated solvents, and the solutions obeyed the scaling law . However, when PBIC was dissolved in benzene the l_p was greatly reduced and the scaling law now was , consistent with a worm-like conformation. On the other hand, POIC dissolved in chlorinated and benzenic solvents exhibited a worm-like conformation and the scaling was . These results were contrasted with those of hydroxypropyl cellulose (HPC) aqueous solutions, which exhibit worm-like conformation, the solutions obeyed the scaling η_o ∝ c^2.5 . Finally, the shear viscosity of the polyisocyanates and HPC obeyed the Saito scaling, valid for anisotropic particles in solution.     

Regeneration and utilization of waste phenolic formaldehyde resin: A performance investigation

Recycled thermosetting phenolic formaldehyde (RPF) resins were pulverized to micron-sized powders and successfully reused as an effective component by reactive-injecting with neat phenolic formaldehyde (PF) and/or trioxymethylene (TOX) to prepare regenerated phenolic formaldehyde (i.e., and ). Tensile strength (σ_f), impact strength (I_s), and density (ρ) of and specimens were reduced as RPF concentrations or average particle sizes increased. It is worth emphasizing that σ_f, I_s, and ρ of each reaction-injected series having a fixed RPF concentration and average particle size improved to a maximum value, as TOX concentrations reached a corresponding optimal value. This is the first investigation to report that σ_f and I_s of proper regenerated PF/RPF/TOX specimens using ≦20 wt % RPF waste were ≥ 95% of those of the virgin reaction-injected PF. Possible reasons accounting for these improved mechanical properties were proposed based on results from their Fourier transform infrared analysis (FTIR). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47445.     

Elucidation of Interactions between l-Ascorbic Acid and Mixed Micellar Aggregates of Catanionic {Sodium Dodecylsulfate + Cetyltrimethylammonium Bromide} Surfactants via Physicochemical and Spectroscopic Studies

Surfactant micelles mimic the microenvironment present in biological systems and can act as a medium for antioxidant studies. Moreover, the thermodynamic profile of micellization and spectroscopic studies provides very good information about interactions in these systems. Thus, the mixed micellar behavior of sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) at varying mole fractions of SDS was studied in (0.01, 0.02, and 0.03) mol kg⁻¹ ʟ-ascorbic acid_(aq) solutions with the aid of various techniques viz., conductivity, density and sound velocity, and spectroscopy. From the CMC values of the mixed surfactants, the degree of ionization (β) and thermodynamic parameters (, , and ) were evaluated at 298.15, 308.15, and 318.15 K. The UV absorption spectra were recorded in (1–3) × 10⁻⁴ mol kg⁻¹ ʟ-ascorbic acid_(aq) solutions at various mole fractions of SDS. The proton (¹H) NMR spectra of mixed (SDS + CTAB) surfactants were studied in (0.01–0.03) mol kg⁻¹ ʟ-ascorbic acid solutions. Hydrodynamic diameters (D_h) of mixed micellar aggregates were obtained from the dynamic light scattering (DLS) studies. The present studies suggest the predominance of ionic-hydrophilic interactions between the ionic head groups {O-SO₃⁻ or N⁺ (CH₃)₃} of surfactants and the polar (–OH, –C=O and –O–) sites of ʟ-ascorbic acid.     

Study on single and binary catalytic systems of pyridine-imine catalysts based on nickel and iron in synthesis of reactor blends and low-density polyethylene nanocomposites

In the presence of modified methylaluminoxane as cocatalyst, the behavior of a binary catalytic system based on pyridine-imine nickel ( N ) and iron ( F ) catalysts was evaluated in order to reach a proper mixture of polyethylene (PE). A computational study along with kinetic profile suggested that the catalyst F with higher electron affinity (A) and electrophilicity (ω) in the methyl cationic active center and stronger interaction with the monomer led to high integrated monomer consumption and higher activity. In addition, the samples produced by the mixture of catalysts showed a higher value of [19.4 × 10⁴ g (PE) mol (Fe+Ni)⁻¹ h⁻¹)], melting point (127.8 °C), and crystallinity extent (41.29%) than the samples produced by the single catalysts. The addition of multiwalled carbon nanotubes (MWCNT) into the polymerization media reduced the activity of catalysts [from 7.50 × 10⁴ to 0.66 × 10⁴ g (PE) mol (Fe+Ni)⁻¹ h⁻¹] and the thermal properties of the low-density polyethylene nanocomposite samples. However, the sample containing 2.33% MWCNT_20-30 improved the total thermal stability of the neat polyethylene blend up to 400 °C. Scanning electron microscope images of the samples demonstrated irregular to virtually uniform morphologies were obtained through the in situ and solution-mixing techniques. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47376.     

Correlation between the mechanical and dielectric responses in polymer films by a fractional calculus approach

A fractional calculus approach was used to study the correlation between the complex elastic modulus and the complex relative permittivity for a polystyrene (PS) film with thickness of ~80 μm. Experimental measurements were carried out using dynamic mechanical analysis and dynamic dielectric analysis. Experimental results show the mechanical and dielectric manifestations of the main relaxation (glass transition process), whose molecular mobility was analyzed by two innovative models: a mechanical fractional model and a dielectric fractional model. Parameters of fractional models show that, when temperature increases, the molecular mobility of the main relaxation also increases, but the cooperativity of mobility decreases. Besides, molecular mobility is greater in the mechanical manifestation of the main relaxation than in the electric manifestation. From theoretical results obtained from fractional models for the isochronal mechanic storage modulus, E′(T) , and the isochronal relative permittivity, , a correlation model for mechanical and dielectric properties of PS film was obtained. This correlation model describes in function of E′(T) . These results suggest that this correlation model can be used to study molecular mobility of mechanical and dielectric dynamic properties of the polymer films samples and predict changes in their behavior by modifying ambient conditions.     

Influence of gel preparation concentration on statistical mechanics of poly(dialkylaminoethyl methacrylate) gels on the basis of scaling concept: Toward tunable elasticity and thermomechanical parameters

In order to evaluate the scaling parameters of weakly cationic crosslinked network structures, poly(dialkylaminoethyl methacrylate)-based hydrogels were synthesized via free-radical crosslinking in aqueous solution varying systematically concentration of pregel solution. Based on the gel-preparation concentration, variation in structural properties, effective crosslinking density, average molecular weight of polymer chains, and thermodynamic parameters from combined swelling and elasticity results were discussed using the scaling theory to predict various exponent identities. The concentration dependence of compressive elastic modulus as-prepared state was described by a power-law relationship with the exponent of m = 3.55 indicating the importance of the trapped entanglements. Two structural characteristics, the network chain length N and the average molecular weight of polymer chains have inverse dependence on the gel-preparation concentration in the matrix, while the compressive moduli and effective crosslinking density show completely direct dependence. Experimentally determined N values of PDMAEMA hydrogels first decrease with increasing up to 0.2972 and the dependence of N on the gel-preparation concentration gives the relation with a scaling parameter n = −1.80, which coincides with the prediction of scaling theory. Acceptable agreement was found between the estimate of crosslink density fluctuations deduced from mechanical measurements and the results derived from independent swelling observations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48350.     

Quantification and elucidation of the UV-light triggered initiation kinetics of TPO and BAPO in liquid acrylate monomer

The initiation kinetics of two important UV-light-triggered initiators for the radical polymerization [diphenyl-2,4,6-trimethyl benzoyl phosphine oxide (TPO) and phenyl-bis(2,4,6-trimethyl benzoyl) phosphine oxide (BAPO)] has been quantified in dependence on the initiator concentration (0.25–2 mol %), the light intensity at 365 nm (0–2000 mW cm⁻²), the thickness of the sample (50–200 μm), the temperature (25–80 °C), the monomer [2-ethyl hexyl acrylate (EHA) and 2-ethyl hexyl methacrylate (EHMA)] and the atmosphere (oxygen free and air) directly in the liquid acrylate monomer. The determination of the kinetic parameters was done by applying two independent procedures: (1) following the initiator decay with respect to the irradiation time, evaluated by radiometric measurements of the UV-light absorption at 365 nm and (2) via titration of the initiation process by using defined under-stoichiometric to stoichiometric amounts of TEMPO as inhibitor, evaluated by means of FTIR-ATR spectroscopy. The validity of the titration procedure was proven by means of ¹³C and ³¹P NMR studies of ¹³C-labeled TPO and was explained by a Lewis acid/base interaction between the carbonyl carbon of the initiator and the oxygen of TEMPO. Both methods resulted in very close kinetic parameters. Thus, reliable values for the extinction coefficients ε₃₆₅ at 365 nm, for the effective rate constants of the α cleavage (containing the quantum yield and the initiator efficiency) when dissolved in the liquid monomer could be provided for both initiators for the first time. The effect of dioxygen quenching in dependence of sample thickness and the temperature dependence on the initiation step were evaluated. EHA was compared with EHMA as liquid monomer, and a yet unmentioned inhibition in case of EHMA was discovered. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48357.     

Electrical properties and the role of inhomogeneities at the polyvinyl alcohol/n‐inp schottky barrier interface

In this work, we have investigated the electrical properties of Au/n‐InP contacts with a thin layer of polyvinyl alcohol (PVA) as an interlayer. The current–voltage (I–V) and capacitance–voltage (C–V) measurements are carried out in the temperature range of 175–425 K. The Au/PVA/n‐InP Schottky structure show nonideal behaviors and indicates the presence of a nonuniform distribution of interface states. The temperature dependent interface states densities (N_SS), ideality factor and barrier height are obtained. An abnormal decrease in zero‐bias barrier height (BH) and increase in the ideality factor ( ) with decreasing temperature have been explained on the basis of the thermionic emission theory with Gaussian distribution (GD) of the BHs due to the BH inhomogeneities. The experimental I–V characteristics of Au/PVA/n‐InP Schottky diode has revealed the existence of a double GD with mean BH values of ( ) of 1.246 and 0.899 eV and standard deviation ( ) of 0.176 and 0.137 V, respectively. Consequently, the modified conventional activation energy versus plot gives and Richardson constants ( ) and the values are 1.17 and 0.71 eV and 9.9 and 6.9 A/cm² K², respectively, without using the temperature coefficient of the BH. The effective Richardson constant value of 9.9 A/cm² K² is very close to the theoretical value of 9.4 A/cm² K² for n‐InP. The discrepancy between Schottky barrier heights estimated from I–V and C–V measurements is also discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39773.     

Optical transition properties,internal quantum efficiencies,and temperature sensing of Er3+ doped BaGd2O4 phosphor with low maximum phonon energy

The hosts with low maximum phonon energy (MPE) are preferred since the nonradiative consumption of the luminescence centers in them are low. Among the low MPE hosts, the oxide ones are more favored owing to their excellent stability and easy synthesis. In this work, the optical and spectroscopic properties of BaGd₂O₄:Er³⁺ phosphor were studied. The MPE of BaGd₂O₄ host was observed from Eu³⁺ phonon sideband (PSB) spectrum and Raman spectrum to be 477 cm⁻¹ which does not second to the fluoride hosts. The refractive index, which is indispensable for Judd–Ofelt calculation, was confirmed from the both approaches of the Eu³⁺-probe and the band gap energy, and the similar refractive indices were confirmed, therefore the average refractive index 2.01 was used in the Judd–Ofelt calculation. The Judd–Ofelt parameters of Er³⁺ in BaGd₂O₄ host was confirmed to be = 7.91 × 10⁻²¹ cm², = 2.36 × 10⁻²¹ cm², and = 9.00 × 10⁻²² cm². Furthermore, the internal quantum efficiencies for ⁴F_9/2 and ⁴I_J (J = 9/2, 11/2, and 13/2) levels were determined. Finally, the optical temperature sensing properties were studied in detail, and the temperature calibration curve was experimentally derived, meanwhile the maximum absolute sensitivity was confirmed to be 0.0028 K⁻¹.     

Viscoelastic Behavior of Synthesized Liquid Soaps and Surface Activity Properties of Surfactants

In the present work, a rheological study of liquid soaps prepared from different mixture of surfactants as a function of surfactant type and concentration was performed. The curves of shear stress vs. shear rate and viscosity vs. shear rate were recorded at constant temperature, 294 ± 0.1 K. The surface activity properties were also studied. The results of the study showed that values of surface tension, γ, were in the range 31–40 mN m⁻¹ and the critical micelle concentration (CMC), was of the order 10⁻⁴ mol L⁻¹. The calculated maximum surface excess, Γ_max, varied from 2.40 to 3.66 μmol m⁻², while minimum area per molecule, A_min, varied from 41.1 (for amphoterics) to 81.4 Ų (for nonionic surfactants). The standard free energy of micellization, −29.8 and −29.3 kJ mol⁻¹ for anionic and amphoteric surfactants, respectively, were while values for nonionic surfactants varied between −31.8 and − 30.3 kJ mol⁻¹. The free energy of adsorption, was the lowest for amphoteric surfactants (−37.9 kJ mol⁻¹), followed by anionics (−40.4 kJ mol⁻¹) and nonionics (−43.34 to −46.84 kJ mol⁻¹), indicating that micellization process is spontaneous in the examined medium. The synthetized liquid soaps show pseudoplastic behavior and they achieved pipe flow. The results of this research indicate that flow behavior was affected significantly by the ionic charge of the surfactant and the ionic strength of the formulation, suggesting that the flow behavior could be changed by manipulating the choice of the surfactant and salinity. The pH value of all liquid soaps examined were weakly acidic, in the range of 5.0–6.4.     

High-Performance All-Solid-State Supercapacitor Electrode Materials Using Freestanding Electrospun Carbon Nanofiber Mats of Polyacrylonitrile and Novolac Blends

Herein, this paper reports a facile method to prepare electrospun carbon nanofiber mats (ECNFMs) with high specific surface area and interconnected structure using polyacrylonitrile (PAN) as a precursor and novolac resin (NOC) as a polymer sacrificial pore-making agent. Without additional treatment, the prepared ECNFMs have a highly porous structure because NOC decomposes in a wider temperature range than most polymer activators. The NOC content in the PAN nanofibers shows important effects on porosity. The BET specific surface area of ECNFMs reaches a maximum of 1468 m² g⁻¹ when the precursor nanofibers contained 30 wt% NOC (ECNFM-3) after carbonization at 1000 °C. The supercapacitor device from ECNFM-3 electrode and all-solid-state electrolyte shows excellent cycling durability and high specific capacitance: ≈99.72% capacitance retention after 10 000 charge/discharge cycles and ≈320 mF cm⁻² at 0.25 mA cm⁻². Furthermore, it shows a large energy density of ≈11.1 $\mu$Wh cm⁻² under the power density of 500 mW m⁻². Activation of carbon nanofibers simply by the addition of NOC into precursor nanofibers can offer a handy way to prepare ECNFMs for high-performance all-solid-state supercapacitors and other potential applications.     

A new method to determine monomer concentration in the polymer particles of emulsion polymerization systems by dynamic light scattering

In the published article cited above, by considering corrections made on the eq. (19) which will be discussed in the next section, Figure 6 should be replaced with a following new Figure 1. Hence, and values of 0.379 and 5.68 mol.dm^?3, respectively, on pages 1055, 1061, and 1062 should be changed to their accurate values of 0.426 and 5.29 mol.dm^?3, respectively.     

Crosslinked anion exchange membrane with improved membrane stability and conductivity for alkaline fuel cells

As a core component of anion exchange membrane (AEM) fuel cells, it has practical significance to improve the performance of AEMs. However, it is difficult to obtain AEM with both good stability and high conductivity. In this study, a series of AEMs were prepared by chloromethylation, quaternization, and crosslinking reactions. The quaternization reaction was carried out first to ensure that there are abundant quaternary ammonium groups on AEM and enhance the conductivity of membrane. N,N,N′,N′-tetramethylethylenediamine was used as a crosslinker to improve membrane stability and mechanical property. A simple, mild, and cost-effective AEM synthetic route was developed. This strategy achieves a certain balance of electrochemical and physical properties. The effect of the crosslinking reactions on the property of membrane was evaluated. Crosslinked membranes have better dimensional stability (water uptake: 20.2% and swelling ratio: 2.1%), mechanical properties (55.84 MPa), and alkaline stability because crosslinked structures result in large steric hindrance. The mutually independent quaternization and crosslinking reaction do not affect the electrochemical performance of membranes; in the crosslinking reaction stage, crosslinker also reacted as quaternization agent and increased the number of reactive groups in AEM. Thus, the resulting crosslinked AEM exhibits higher ion exchange capacity and ionic conductivities (46.4 mS cm⁻¹). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48169.     

Synchrotron x-ray spectroscopy investigation of the Ca1−xLnxZrTi2−x(Al,Fe)xO7 zirconolite ceramics (Ln = La,Nd, Gd,Ho, Yb)

When incorporating actinides into zirconolite for high-level radioactive waste immobilization, Al³⁺ and Fe³⁺ ions generally act as charge compensators. In this study, we rationally designed a series of (Ln = La, Nd, Gd, Ho, Yb) to unravel the dopant solubility and evolutions of the crystalline phase and local environment of cations through synchrotron X-ray methods. It was found that single zirconolite phase is difficult to obtain and the fraction of perovskite have an increase with x from 0.1 to 0.9 in . Formation of both zirconolite-2M and zirconolite-3O phases was observed in and . Phase transformation from zirconolite-2M to 3O occurs at x = 0.7 for while x = 0.9 for . The solubility of and to form single zirconolite-2M can reach to 0.9 f.u. and 0.7 f.u., respectively. The evolution of lattice parameters of zirconolite in is greatly related to the ionic radii of cations and substitution mechanism among the cations. X-ray absorption near edge spectroscopy revealed that Fe³⁺ ions replace both five- and six-coordinated Ti sites and the ratio of TiO₅ to TiO₆ decreases when increasing dopant concentration in the . For the local environment of Zr⁴⁺, the major form is ZrO₇ with a trace of ZrO₈.     

A green resin acid ester surfactant from colophony and xylitol: Synthesis,self-assembly in nonaqueous solvents,and thermodynamics

An environmental friendly oil-soluble surfactant colophony xylitol ester (CXE) is first synthesized from natural colophony and xylitol with the use of hot-compressed water and subcritical CO₂ in a steel autoclave. In this solvent-free system, the conversion of the reaction was up to 90.30% in 4 h. Thermal gravimetric analysis determine that its thermal stability was as high as 310°C. CXE is effective in reducing the surface tension of six different organic solvents. The greatest effect of surface tension reduction by CXE is in the case of dimethyl sulfoxide, the surface tension of the surfactant solution was as low as 36.26 mN/m at its critical micelle concentration value of 7.49 mM; The greatest effect of interfacial tension reduction by CXE is in the case of turpentine and water, the interfacial tension low to 1.51 mN/m. Furthermore, transmission electron microscope and particle size measurement showed that CXE is successfully self-assembled into micelles, vesicles, and heteromorphic vesicles in six kinds of organic solvents. Finally, the critical micelle concentration curves at different temperatures provided the thermodynamic parameters of the aggregate formation, found that , , and are negative and increased as the temperature increased.     

Conductivity of iron-doped strontium titanate in the quenched and degraded states

The electrical behavior of iron-doped strontium titanate (Fe:SrTiO₃) single crystals equilibrated at 900°C and quenched below 400°C at various oxygen partial pressures () was investigated via impedance spectroscopy and compared to defect chemistry models. Fe:SrTiO₃ annealed and quenched between 1.2 × 10⁻¹⁴ and 2.0 × 10⁻⁴ Pa exhibits a conduction activation energy (E_A) around 0.6 eV, consistent with ionic conduction of oxygen vacancies. However, sudden changes in E_A are found to either side of this range; a transition from 0.6 to 1 eV is found in more oxidizing conditions, while a sudden transition to 1.1 and then 0.23 eV is found in reducing These transitions, not described by the widely used canonical model, are consistent with predictions of transitions from ionic to electronic conductivity, based on first principles point defect chemistry simulations. These models demonstrate that activation energies in mixed conductors may not correlate to specific conduction mechanisms, but are determined by the cumulative response of all operative conduction processes and are very sensitive to impurities. A comparison to electrically degraded Fe:SrTiO₃ provides insight into the origins of the conductivity activation energies observed in those samples.