ASSOCIATION OF ETHYLENE—VINYL ACETATE COPOLYMER IN DILUTE SOLUTIONS Ⅲ. CRITICAL ASSOCIATION CONCENTRATION

Association behavior of ethylene vinyl acetate (EVA) copolymer in foursolvents 1, 2-dichloroethane (DCE), cyclohexane (CYH), xylene (XYL) and chloroform(CF) has been investigated by dilute solution viscometry The critical association concen-tration (C_A) was determined at which the incipient decrease in slope of the η_(sp)/C～ Ccurve in solutions at the dilute regime. Our results showed that whether the CA couldexist depends on solvent property. The values of CA in DCE increase with increasing, oftemperature and vinyl acetate (VA) content in EVA and decreasing of molecular weight ofEVA.

DILUTE SOLUTION BEHAVIOR OF CHITOSAN IN DIFFERENT ACID SOLVENTS

Dilute solution behavior of chitosan was studied in formic acid, acetic acid, lactic acid andhydrochloric acid aqueous solution under different pH values. The reduced viscosities, η_(sp)/C,ofchitosan solutions were dependent on the properties of acid and pH value of solvents. For a givenchitosan concentration, η^(sp)/C decreased with the increase of acid concentration, or decreasing pHof solvent, indicating shielding effect of excessive acid similar to adding salt into solution. Thestabilities of dilute chitosan solution in formic acid and lactic acid were better than that in acetic acid and hvdrochloric acid.

Comparison of the Molecular Interaction Volume Model with the Wagner Formulae in the Zn-Pb-In and Zn-Sn-Cd-Pb Dilute Solutions

The coordination numbers in the molecular interaction volume model (MIVM) can be calculated from the commonphysical quantities of pure liquid metals. A notable feature of the model lie in its capability to predict the ther-modynamic properties of solutes in the Zn-Pb-In and Zn-Sn-Cd-Pb dilute solutions using only the binary infinitedilute activity coefficients, and the predicted values are in good agreement with the experimental data of the dilutesolutions.

Intrachain and Interchain Interactions in Polystyrene: Dilute andSemidilutc Solutions

Excimer formation in pyrenyl labeled polystyrene has been investigated in dilutesolution region. The change of the intensity ratio of excimer to monomer (Ie/Im) with increasingconcentration (C), is interpreted by intrachain and interchain interactions. The double logarithmicPlot of Ie/Im vs C displays two critical points, Cs at about 2.5×10-3g/ml and C+ at about 3.2×10-2g/ml. In dilute region C<Cs, excimer formation may be controlled by intrachain interaction.

ITSTUDIES ON THE EFFECT OF UREA ON THE COMPATIBILITY OF PMMA/PVC MIXTURES IN DMF BY A DILUTE- SOLUTION VISCOMETRY METHOD

The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.

SYNTHESIS OF A NOVEL AMPHIPHILE, 4-[4-(4-DECYLOXYPHENYLAZO) NAPHTHYLOXY] BUTYL TRIMETHYLAMMONIUM BROMIDE, AND ITS SELF-ASSEMBLING BEHAVIOR IN DILUTE AQUEOUS SOLUTION

A novel amphiphile of 4-[4-(4-decyloxyphenylazo) naphthyloxy] butyl trimethylammonium bromide has been synthesized. It can form the stable bilayer in dilute aqueous solution.

Potassium thiocyanate additive for PEDOT:PSS layer to fabricate efficient tin-based perovskite solar cells

The commercialized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)is usually used as hole transport layers(HTLs)in tin-based perovskite solar cells(TPSCs).However,the further development has been restricted due to the acidity that could damage the stability of TPSCs.Although the PEDOT:PSS solution can be diluted by water to decrease acidity and reduce the cost of device fabrication,the electrical conductivity will decrease obviously in diluted PEDOT:PSS solution.Herein,potassium thiocyanate(KSCN)is selected to regulate the properties of PEDOT:PSS HTLs from the diluted PEDOT:PSS aqueous solution by water with a volume ratio of 1:1 to prepare efficient TPSCs.The effect of KSCN addition on the structure and photoelectrical properties of PEDOT:PSS HTLs and TPSCs have been systematically studied.At the optimal KSCN concentration,the TPSCs based on KSCN-doped PEDOT:PSS HTLs(KSCN-PSCs)demonstrate the champion power conversion efficiency(PCE)of 8.39%,while the reference TPSCs only show a champioan PCE of 6.70%.The further analysis demonstrates that the KSCN additive increases the electrical conductivity of HTLs prepared by the diluted PEDOT:PSS solution,improves the microstructure of perovskite film,and inhibits carrier recombination in TPSCs,leading to the reduced hysteresis effect and enhanced PCE in KSCN-PSCs.This work gives a low-cost and practical strategy to develop a high-quality PEDOT:PSS HTLs from diluted PEDOT:PSS aqueous solution for efficient TPSCs.

A UNIFIED ENERGY APPROACH TO A CLASS OF MICROMECHANICS MODELS FOR COMPOSITE MATERIALS

Several micromechanics models for the determination of composite moduli are investigated in this paper,including the dilute solution,self-consistent method,generalized self-consistent method,and Mori-Tanaka's method.These mi- cromechanical models have been developed by following quite different approaches and physical interpretations.It is shown that all the micromechanics models share a common ground,the generalized Budiansky's energy-equivalence framework.The dif- ference among the various models is shown to be the way in which the average strain of the inclusion phase is evaluated.As a bonus of this theoretical development,the asymmetry suffered in Mori-Tanaka's method can be circumvented and the applica- bility of the generalized self-consistent method can be extended to materials contain- ing microcracks,multiphase inclusions,non-spherical inclusions,or non-cylindrical inclusions.The relevance to the differential method,double-inclusion model,and Hashin-Shtrikman bounds is also discussed.The application of these micromechanics models to particulate-reinforced composites and microcracked solids is reviewed and some new results are presented.

DIPOLE POLARIZATION RELAXATION AND MOLECULAR STRUCTURE OF MAIN-AND SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS

Molecular mobility in thermotropic polyesters and side-chain polymers with different struc-ture of mesogens and spacers has been studied by dielectrical method in dilutesolutions. The results made it possible to establish the multiplicity of dielectric relaxationtransitions which reflects the small- and large-scale types of molecular motion. It was shownthat dielectric relaxation processes occurring in accordance with local mechanism (relaxationtimes 10^(-9)--10^(-7)s. and the activation energy 10--50kJ/mol) are due to the mobility of kineticchain elements of different length within a monomer units. It was found that the dielectricrelaxation process connected with a large-scale form of molecular motion (relaxation times10^(-5)--10^(-6)s. and the activation energy 100kJ/mol) did not depend on the molecular massbut was infiuenced by factors changing the conformational state of the macromolecule. It isestablished tha the cooperative reorientation mobility of associated mesogenic fragments isthe source of the large-scale process.

Miscibility on blends of PVA and PFSA by viscometry

The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of AB and μ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution.

Improved anticorrosion performance of mixed valence Mnmodified ZnO dilute magnetic solid solution with multilevel selfassembled network structure

The design and performance prediction of efficient anticorrosion materials is a work full of value,novelty,and challenges.In this work,from the perspective of nanostructure and composition,ZnO-based dilute magnetic solid solution(DMSs)with hydrophobic micronano network structure was synthesized through the self-induced effect of raw materials,the impact-resistant network structure,complex micro-channels,and densely nested layers resisted electrolyte intrusion.Further,the doping of mixed valence Mn element endowed the solid solution with dilute magnetic properties,so the Lorentz force from micromagnetic field changed the movement path of electrons produced by the anode reaction to improve the corrosion inhibition ability of the protective layer.Under the synergy of morphology and magnetism,the corrosion resistance of the DMSs materials was 555.4%and 173.8%higher than that of epoxy resin and ZnO shielding layer,respectively.Besides,a valuable phenomenon was found that the photocatalytic property of DMSs materials was positively correlated with their corrosive defense.In conclusion,this research provided a novel design idea for new high-efficiency anticorrosion materials.

Carbon Dioxide Sequestration via Steelmaking Slag Carbonation in Alkali Solutions: Experimental Investigation and Process Evaluation

Carbon dioxide mineral sequestration with steelmaking slag is a promising method for reducing carbon dioxide in a large- scale setting. Existing calcium oxide or calcium hydroxide in steelmaking slag can be easily leached by water, and the formed calcium carbonate can be easily wrapped on the surface of unreacted steelmaking slag particles. Thus, further increase in the carbonation reaction rate can be prevented. Enhanced carbon dioxide mineral sequestration with steel- making slag in dilute alkali solution was analysed in this study through experiments and process evaluation. Operating conditions, namely alkali concentration, reaction temperature and time, and liquid-to-solid ratio, were initially investigated. Then, the material and energy balance of the entire process was calculated, and the net carbon dioxide sequestration efficiency at different reaction times was evaluated. Results showed that dilute alkali solution participated in slowing down the leaching of active calcium in the steelmaking slag and in significantly improving carbonation conversion rate. The highest carbonation conversion rate of approximately 50% can be obtained at the optimal conditions of 20 g/L alkali concentration, 2 mL/L liquid-to-solid ratio, and 70 ℃ reaction temperature. Carbonation reaction time significantly influences the net carbon dioxide sequestration efficiency. According to calculation, carbon dioxide emission of 52.6 kg/t- slag was avoided at a relatively long time of 120 min.

regeneration of thermally deactivated commercial V-W-Ti catalysts

An effective method for the regeneration of thermally deactivated commercial monolith SCR catalysts was investigated. Two types of regenerated solutions, namely NH4C1 （l mol/L） and dilute H2SO4 （0.5 tool/L）, were employed to treat the used catalyst. The effects of temperature and the regeneration process on the structural and textural properties of the catalysts were determined by X-ray diffraction, scanning electron microscopy, N2 adsorption/desorption, elemental analysis and Fourier transform infrared spectroscopy. The results suggest that the anatase phase of the used catalyst is maintained after exposure to high temperatures. Some of the catalytic activity was restored after regeneration. The catalyst regenerated by aqueous NH4C1 had a higher activity than that of the catalyst treated by dilute H2SO4. The main reason is that the NH3 generated from the decomposition of NH4C1 at high temperatures can be adsorbed onto the catalyst which promotes the reaction. The aggregated V205 were partially re-dispersed during the regeneration process, and the intrinsic oxidation of ammonia with high concentrations of O2 is a factorthat suppresses the catalytic activity.