The application of reed-vibration mechanical spectroscopy for liquids to detect chemical reactions of an acrylic structural adhesive

There remain a number of unsolved problems about chemical reactions, and it is significant to explore new detection methods because they always offer some unique information about reactions from new points of view. For the first time, the solidification course of a modified two-component acrylic structural adhesive is measured by using reed-vibration mechanical spectroscopy for liquids （RMS-L） in this work, and results show that there are four sequential processes of mechanical spectra with time. The in-depth analyses indicate that RMS-L can detect in real-time the generation and disappearance of active free radicals, as well as the chemical cross-link processes in the adhesive. This kind of real-time detection will undoubtedly facilitate the study of the chemical reaction dynamics controlled by free radicals.

In situ Fourier Transform Infrared Spectroscopy Diagnostic for Characterization and Performance Test of Catalysts

The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior （temperature-programmed reduction/temperatureprogrammed re-oxidation） as well as the catalytic properties of Co3O4 thin films. The syntheses of Co3O4 were achieved by chemical vapor deposition in the temperature range of 400-500℃. The structure analysis of the as-prepared material revealed the presence of two prominent IR bands peaking at 544 cm-1 （υ1） and 650 cm-1 （υ2） respectively, which originate from the stretching vibrations of the Co-O bond, characteristic of the Co3O4 spinel. The lattice stability limit of Co3O4 was estimated to be above 650℃. The redox properties of the spinel structure were determined by integrating the area under the emission bands υ1 and υ2 as a function of the temperature. Moreover, Co3O4 has been successfully tested as a catalyst towards complete oxidation of dimethyl ether below 340 ℃. The exhaust gas analysis during the catalytic process by in situ absorption FTIR revealed that only CO2 and H2O were detected as the final products in the catalytic reaction. The redox behavior suggests that the oxidation of dimethyl ether over Co3O4 follows a Mars-van Krevelen type mechanism. The comprehensive application of in situ FTIR provides a novel diagnostic tool in characterization and performance test of catalysts.

Observation of selective surface element substitution in FeTe_(0.5)Se_(0.5) superconductor thin film exposed to ambient air by synchrotron radiation spectroscopy

A systematic investigation of oxidation on a superconductive Fe Te_（0.5）Se_（0.5）thin film,which was grown on Nb-doped SrTiO_3（001） by pulsed laser deposition,has been carried out.The sample was exposed to ambient air for one month for oxidation.Macroscopically,the exposed specimen lost its superconductivity due to oxidation.The specimen was subjected to in situ synchrotron radiation photoelectron spectroscopy（PES） and x-ray absorption spectroscopy（XAS） measurements following cycles of annealing and argon ion etching treatments to unravel what happened in the electronic structure and composition after exposure to air.By the spectroscopic measurements,we found that the as-grown FeTe_（0.5）Se_（0.5）superconductive thin film experienced an element selective substitution reaction.The oxidation preferentially proceeds through pumping out the Te and forming Fe–O bonds by O substitution of Te.In addition,our results certify that in situ vacuum annealing and low-energy argon ion etching methods combined with spectroscopy are suitable for depth element and valence analysis of layered structure superconductor materials.

DMS AND ^(13)C NMR STUDIES ON THE COMPATIBILITY AND DYNAMICS OF LATEX BIDIRECTIONAL IPNS AND LATEX IPN OF PVAc/PBA

The compatibility and dynamics of latex bidirectional/nterpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to, a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side- groups of PBA in the LBIPN are longer than those in the LIPN. The relation between the ^(13)C linewidths of PBA and temperature is also discussed.

Reaction mechanism of molten Na OH decomposing Zn_2SiO_4 in willemite

Based on the existing form of Zn2 Si O4 in willemite, the chemical precipitation method was used to synthesize Zn2 Si O4.Through the orthogonal experimentation, the reaction conditions of melten Na OH decomposing Zn2 Si O4 were optimized, and the optimal experimental conditions include reaction temperature of 400 °C, reaction time of 4 h, and alkaline-to-ore molar ratio of 20:1.Based on the optimized experiment, on-line detection for the alkali leaching was made by using Raman spectroscopy; XRD was used to analyze the structure of water leaching residue, to explore the reaction mechanism of Na OH decomposing Zn2 Si O4. The results show that during the reaction process, the Si — O bond in Si O4 is destroyed, and the Na OH inserts itself into the silicate lattice,producing an immediate Na2 Zn Si O4 product. After the alkali leaching process, Zn2+ can be separated from the Si O4 array, which can be released out of the silicate in the form of ZnO.

Mechanism of boron atomization in graphite furnace atomic absorption spectroscopy

The mechanism of the atomization of boron and the enhancement of sensitivity by matrix modifier Sr(NO_3)_2 in graphite furnace AAS were discussed.X-ray diffraction and thermodynamic calculation were applied to study the mechanism of boron atomization with and without matrix mo- difier Sr(NO_3)_2.The formation of boron atom is due to the sublimation of solid boron which derived from the reduction of B_2O_3 by carbon.The enhancement of boron signal in the presence of Sr(NO_3)_2 is due to the formation of SrB_6 before atomization,which decreased the volatization losses of B_2O_3 and retarded the formation of B_4C.

Study of the Properties of Polyurethane-waste Rubber Granulate Composites

1 Results The production of rubber is very high and rises every year. Among other things it is directly connected with the growth of car production. Therefore, the processing of waste rubber and its management must be treated as a global problem. Used rubber may replace conventional fuel and, owing to its low price, can improve the economic effectiveness of combustion. Energy recovery by combustion of car tyres allows for rapid management of rubber waste. However, it is well-known that all kinds of wast...

Insight on Viscoelasticiy of Ti16.7Zr16.7Hf16.7Cu16.7Ni16.7Be16.7 High Entropy Bulk Metallic Glass

High entropy bulk metallic glasses show promising mechanical and physical properties.Dynamic mechanical properties of Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass were investigated by mechanical spectroscopy（or called dynamic mechanical analysis）.The main（α）relaxation was observed in the framework of the loss modulus G″,which is related to the dynamic glass transition behaviour for the glassy materials.From physical model point of view,dynamic mechanical properties of the Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass show good agreement compared with the quasi-point defects theory.

Utilization of nano/micro-size iron recovered from the fine fraction of automobile shredder residue for phenol degradation in water

The study investigates the magnetic separation of Fe from automobile shredder residue （ASR） （ 〈 0.25 mm） and its application for phenol degradation in water. The magnetically separated Fe was subjected to an ultrasonically assisted acid treatment, and the degradation of phenol in an aqueous solution using nano/micro-size Fe （n/m Fe） was investigated in an effort to evaluate the possibility of utilizing n/m Fe to remove phenol from wastewater. The prepared n/m Fe was analyzed by scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The eflects of the dosages ot n/mFe, pH, concentration of phenol and amount of H2O2 on phenol removal were evaluated. The results confirm that the phenol degradation rate was improved with an increase in the dosages of n/mFe and H2O2; however, the rate is reduced when the phenol concentration is higher. The degradation of phenol by n/mFe followed the pseudo-first-order kinetics. The value of the reaction rate constant （k）was increased as the amounts of n/m Fe and H2O2 increased. Conversely, the value of k was reduced when the concentration of phenol was increased. The probable mechanism behind the degradation of phenol by n/m Fe is the oxidation of phenol through hydroxyl radicals which are produced during the reaction between H2O2 and n/m Fe.

Application and mechanism of polysaccharide extracted from Enteromorpha to remove nano-ZnO and humic acid in coagulation process

Enteromorpha polysaccharide （Ep） extracted from alga a novel green coagulant aid for nanoparticles （NPs） and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride （PAC-Ep） coagulants exhibited higher coagulation performance than that of the polyaluminum chloride （PAC） because of the negatively charged NPs suspension and humic aid （HA） solution. Significant high removal efficiencies of dissolved organic matter （94.1%）, turbidity （99.3%） and Zn ions （69.3%） were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including （i） AI^3＋ charge neutralization; （ii） hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; （iii） adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment.