2004 Vol. 17, No. 5

The photo ionization of furan by an intense 25 ns Nd:YAG 532 nm laser has been studied by time-of-flight mass spectrometry. At the laser intensity of 1010~1011 W/cm2, multi-charged ions Can+ (n=2~4) and Ohm+ (m=2~3) appeared in the mass spectra when argon was used as the carrier gas. From the peak splitting and the numeric analysis, the most probable kinetic energies of C2+, C3+ and C4+ were confirmed to be 21、63 and 100 eV respectively, and the most probable kinetic energies of O2+ and O3+ were confirmed to be 20 and 40 eV respectively. It is proposed that the multi-charged ions come from the Coulomb explosion of furan cluster ions produced by multi photon ionization of neutral furan cluster.
The solvent effects on the nonlinear optical properties of para-nitroaniline (pNA) molecule are studied on the base of time dependent density functional theory. The polarized continuum model is used to simulate the influence of the solvent environment of the solute molecule. In the first place, the geometrical structures of pNA molecule in each solvent are optimized by use of density functional theory and the influence of solvent on the geometry of pNA molecule is thus illustrated. Then, the energies and dipole moments of the excited states with pNA molecule in different solvents are computed on the base of time dependent density functional theory. The dispersion relations of the first-order nonlinear hyperpolarizabilities in second harmonic generation process for pNA molecule in different solvents are given by using two-state model for the first time. It is shown that polar solvents have much influence on the nonlinear optical properties. At low frequency radiation field, the theoretical results of the dispersion relation agree well with the experimental results. While at higher frequency radiation field, other methods need to be developed to compute the dispersion relation of the first order nonlinear hyperpolarizability. At last, possible explanations are given for the results and the validity of the two-state model is discussed.
By using the established statistical thermodynamic theory of adsorbate-induced surface stress of adsorption monolayer on the metal surface, the surface stress Δgin the self-assembly of alkane thiolson Au (111) surface has been calculated. The quantitative relations of the surfaces tress Δgwith the length of the alkyl chain of the molecule and with the coverage θ of molecules on Au (111) have been theoretically Studied respectively. The calculated results agree with Bergeretalis experiment, and especially the quantitative discrepancy between the theory and experiment on the sign of the surface stress has been resolved.Among various components of the adsorbate-adsorbate interaction energies in the ad layer, the substrate mediated interaction is significant for the adsorbate-induced surface stress, which shows that the indirect contribution of the adsorption energy of alkane thiols through the substrate-mediated interaction is very important.This physical mechanism is similar to that for chloride monolayer on the Au (111) electrode.
In order to theoretically disclose the linear and nonlinear responses of the Gaussian white noise driven Schrodinger Model of Two Boxes in chemical reaction to a weak periodic perturbation, the rate equation method is used to derive the analytical expression of linear and nonlinear susceptibilities and the signal-to noise ratio according to quadrustable or bistable adiabatic approximations with in different parameter ranges.The analytically approximate result is also compared with that from numerical simulation. For the parameters under concern, the qualitative agreement is observed between the analytic and the numerical first order resonant structures when the noise intensity is not in zero limit. Moreover, the analytic results show that the resonant behavior can occur only in the odd-order harmonic of the model, but the numerical simulation also shows the second-order harmonic resonance, which might be induced by the finite frequency truncations on the Gaussian white noiseor by the indistinguish ability between high-order harmonics and background noise.
The relaxation and electronic structure of the α-Al2O3 (0001) super-cell (2×2) surface with single Al atoms layer-terminated are studied using ab initio quantum-mechanical calculations based on the density functional theory and pseudo potential method. The calculations employ slab geometry and periodic boundary conditions, with the occupied orbitals expanded in plane waves. It is found that the surface relaxation results in the change of surface electronic states by investigating the relaxation and the population of the Al-O atoms of the surface. By analyzing the difference of the density of state and electron charge density between the unrelaxed and relaxed surface, it is obvious that the α-Al2O3 (0001) crystal surface appears on the O-surface state from which is most contribution to the O2p states, and the surface electronic density plotted by electron localization function (ELF) shows the characteristics of surface bonding atoms. The ELF indicates the outmost Al-O ionic bonds of the relaxed surface are much stronger than that of the unrelaxed surface.
With in the framework of distance dependent tight-binding molecular dynamics (DDTBMD), the collision dynamics of sodium cluster Na n has been studied systematically. Some phenomena have been observed at different impact parameters b , such as fusion reaction, deep inelastic collision (DIC) and quasi-elasticcollision, which are similar to the nuclear heavy-ion collisions (HIC). For the system of Na6 (3D) + Na8, the reaction mechanism at b=9a0 is DIC, but when b is equal to 13a0, it corresponds to quasi-elastic collision. Further more the rotation processes during the collisions, are related to the collision energy and parameter. The larger collision energy is, the earlier relative rotation will occur, and the relaxation time becomes shorter and the relative rotation energy is much smaller. There exists maximal relative rotation energy which corresponding to b = 7a0. When b is smaller than 7a0, the rotation energy increases with b increasing, otherwise the energyd ecreases. And the maximal relative rotation energy is corresponding to DIC process. The maximal rotation energy can reach on etenth of total energy, which is much less than that in HIC.
Molecular simulation is a powerful tool in studying properties of complex fluids composed of charged particles such as electrolyte solutions, room temperature ionic liquids and colloid solutions, where the long-range interactions play a determinative role. Several methods have been available for treating the long-range interactions between charged particles and point dipole. These include the Ewald sum (ES), the reaction field and particle-particle particle-mesh methods. Among these approaches, the ES is most commonly used. However, several ES versions have been occurred in the literatures of molecular simulation, and some times it is difficult for one to choose the right formula to use in molecular simulation study. The coulombic interaction energy between charged particles is divided into the sum of real space, reciprocal space and self energy, and theircal culation equations are obtained respectively using electrostatics theory and Fourier transformation method. The Ewald sum formulate have been derived and the clear physical picture involved has been depicted. A Monte Carlo computer simulation for electrostatic interaction energy of charged hard sphere system has been conducted at varying conditions, and a good agreement with MSA is obtained. On this basis the effects on the simulation accuracy and efficiency of real space cut distance r(cut), convergence parameter 1 and reciprocal maximum vector K(max) have been analyzed. From the theoretical and computer simulation presented here, the optimization parameters for rcut, 1 and K(max) are obtained as 0.5 L (i.e. half box length), 5.8 and 3~5, respectively.
Three kinds of Relativistic Effective Core Potentials (RECP) with B3LYP, MP2 and HF methods have been used to work out the structures for the ground state of PuO molecule, whose equilibrium nuclear distances, disassociation energies, spectral constants and harmonic frequencies have been obtained. The ab initio energy data of PuO have been least-square-fitted to the Murrell-Sorbie potential energy function, from which the corresponding spectral constants, the second, third and forth forcec on stants have been derived. The results indicate that SDDRECP with B3LYP method could give the best calculations in agreement with the experimental results. The charge populations, spindensities and dipole moments of PuO molecule to the different RECP sand calculation levels have also been tabled out.
The theoretic study of reaction between BrONO2 and O(3P) is reported by using the molecular orbital ab initio and density function theory (DFT). Equilibrium structural parameters, harmonic vibrational frequencies, total energy and zero energy of reactants, transition states, inter mediates and products during reactions are computed by B3LYP theory level with the basis set 6-311+G(d,p). The transition states and inter mediates of the reaction are verified by frequency analysis, and the relation ship of reactants, transition states, intermediates and products is affirmed by Intrinsic Reaction Coordinate(IRC) calculation. The activation energy of the reaction has also been calculated. Based on the optimized structure, the single point energy of all species is obtained by CCSD(T) with the basis set 6-311+G(d,p). The results show that there are three exothermic channels and their corresponding products are: cis-Br ONO + 3O2, trans-BrONO + 3O2 and BrOO+NO2. The activation energy of three channels is 91.58, 101.25, 51.17kJ/mol under B3LYP and 141.19, 148.39, 103.21 kJ/molunder CCSD(T) theory level. The third channel is the dominant channel.
The electronic structures of electrode material LiMn2O4 and Li5Mn7CoO8 for the lithium ion battery are studied by employing an ab initio “atomic-basis + norm-conserving non-local pseudopotentias” method. The calculation results of the electronic structure of an ode material LiMn2O4 show that the valence band of LiMn2O4 are mainly made up of 3d atomic orbtics of Mn(8) and Mn(9), and 2 p atomic orbits of O(7), O(6) and O(4), while the conduction band contains essentially 3d orbits of Mn (8) and Mn (9), and 2p atomic orbits of O(7). At the same time, the computing results of electronic structure of electrode material Li5Mn7CoO8 indicate that the reversible capacity of the electrode can decrease and discharge voltage reduces in the cycling, and the net charge of partial lithium ions of the active electrode material and the interaction between lithium ions and oxygen ions increase. While the cycling performance of the anode can improve due to the structural stabilization of the material Li5Mn7CoO8 corresponding to the decrease of the valence band width and enhancement of the Co-O bond.
The physisorption of hydrogen stored in armchair multi-walled carbon nanotubes (MWCNTs) is simulated by the grand canonical Monte Carlo (GCMC) method on the condition of 10 MPa at normalt emperature. Hydrogen-hydrogen and hydrogen-carbon interactions are both modeled with Lennard-Jones potential. The hydrogen storage in double-walled carbon-nanotubes (DWCNTs) has been investigated on the condition that the internal or external radius is changed while the other radius remains constant. The results show that hydrogen molecules are mostly absorbed near the tube walls, and the hydrogens to rage capacityisim proved effectively when the difference between the internal radius and the external radius increases from 0.34 to 0.61 or 0.88 nm. Its simple theoretic explanation also is given. Further more, the capacity of hydrogen physisorbed in there-walled carbon nanotubes (TWCNTs) is calculated when the wall-wall distance is 0.34, 0.61 and 0.88 nm respectively. Then its hydrogen storage capacity is compared with that of single-walled carbon nanotubes (SWCNTs) and DWCNTs, and it is discovered that the capacity of hydrogen physisorbed in MWCNTs decreases as the number of wall increases.
The relationship between the vector version and tensor version of Frank distortion energy for the liquid crystal was established, through which the relationship between the Frank elastic constants and the expansion coefficients of spatial derivatives for the orientational order parameter Sij of liquid crystalline polymer was obtained. Ginzberg-Landau equation for the orientational order parameter Sij was numerically solved by using the cell dynamical system, which involves a free energy functional containing Landau-de Gennes orientational free energy, Maier-Saupe anisotropic interaction free energy and Frank distortion free energy. Incase of the splay elastic constant being much lager than the bend elastic constant, the evolution process of band textures in liquid crystalline polymer during the shear relaxation and its small angle light scattering patterns were simulated. The influence of preshear rate on the band forming and band structure was investigated. It was found that the formation of longitudinal band textures is due to the much rapider longitudinal splay relaxation than the latitudinal bend relaxation, and the induced times of band forming and the characteristic length of band structure decrease with the increasing of preshear rate, which is consistent with the experimental results.
The novel complex {H[Cu(trans-Hcydta)]?2Bzim?1.5H2O?0.5MeOH?HClO4} has been synthesized in aqueous solution, where Hcydta=1,2-cyclohexanediamine-tetraceticacid, Bzim=benzimidazole. The crystal structure of the copper complex has been determined by X-ray diffraction. The crystal belongs to monoclinic, with space group P2(1) /c with a=1.6360(6), b=1.3814(5), c=1.5503(5) nm, β=90.885(7)o, V=3.503(2) nm3, Z=4, Dx=1.495 g/cm3, μ(MoKa)=7.74 cm-1, F(000)=1640, R1=0.0750, wR=0.1526. The bond lengths of Cu-O are 0.2191(4), 0.1974(4), 0.1932(4) nm, respectively. The copperatom has a distorted cone. The study on the title complex has been performed, with quantum chemistry calculation by means of G98W package and taking Lanl2dz basis set.
In order to investigate the interaction between exogenous Cu2+ and Polyphenoloxidase (PPO) from Nictiana Tobacum, the Cu2+-induced resistant-denaturation against guanidine hydrochloride(Gdn-HCl) was studied by the following enzymatic activity assay, fluorescence spectroscopy and circular dichroism (CD). The results show that the GdnHCl-induced unfolding is a two-state process with no detectable inter mediate state in the absence of exogenous Cu2+, while the GdnHCl-induced unfolding in the presence of 10.0 mmol/L exogenous Cu2+ follows a three-state transition with an intermediate state, which results from the fact that Cu2+ increases the structural stability of native PPO and its intermediate. In terms of enzymatic activities, 6 mol/L GdnHCl makes PPO lose 81.4% of its original activity after 5 min, inactivate completely after 30 min, while in the presence of 10.0 mmol/L exogenous Cu2+, only 39.4% and 75.1%, after 5 and 30 min respectively. According to the CD measurements, the relative average fractions of α-helix, anti-parallel2-sheet, 2-turn/parallel 2-sheet, aromatic residues and disulfide bond, and random coil/γ-turn are 1.1%, 3.8%, 3.3%, 7.5% and 84.3%, respectively, in the 6.0mol/L GdnHCl containing no CuSO4, but34.2%, 13.7%, 21.0%, 9.5% and 21.6%, respectively, in the same concentration of Gdn-HCl containing 10mmol/L CuSO4.
An ewacylpyrazolone Schiff base and its metal complexes were synthesized. The electrochemical behaviour of complexes was studied. In non-aqueous solvent, the new Schiff base 1-phenyl-3-methyl-4-(2-thenoyl)-5-pyrazolone-2-alanine (HL) was synthesized by the reaction of 2-alanine with 1-phenyl-3-methyl-4-(2-thenoyl)-5-pyrazolone and its complexes UO2(II), Cu(II), Co(II) and Fe(II) were obtained from refluxing a solution of Schiff base and metal nitrate. The polarographic wave of Cu(II) complex was determined at 1.24V(vs.SCE) in the medium of HAc-NaAc (PH=4.6). On the basis of elemental analysis and molar conductance, the general formula of the complexes, [UO2L2]?H2O,[CuL2]?2H2O,[CoL2]?2H2O and [FeL2]?2H2O, were given. They were characterized by IR, UV-visible, 1H NMR, 13CNMR, thermal analyses and magnetic moments. The results show that the metal ions except UO2 2+ exhibit six coordination in the complexes. The peak current is produced by the reduction of Cu2+ in the copper complex, and the number of electron transfer is 1 at electrode reaction.
Using the Kelvin probe and the optical second harmonic generation (SHG) measurement, the Space charged phenomenon and the non-linear optical effects at the interfaces of the coppertetra-tert-butyl phthalocyanine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal (AlorAu) coated glass slide substrate were in vestigated. The surface potentials decreaseas the film thickness increases and eventually approaches a saturated value. The SHG has been detected although there is a centro-symmetric systemin the Cuttb Pcmolecular, and avery strong SH signal can be investigated at 1260 nm band for Cuttb Pc/Al samples. According to a proposed physical model for Cuttb PcLB film/metal, the nonlinear mechanism were analyzed by using electromagnetic wave theory. It is considered that the enhanced SH peak of CuttbPc/Al is attributed to the strong surface potential aroused by SCIEF at the interface, and shows that the production of SH signal is correlated closely with the electrostatic phenomena at the interface.
Experimental adsorption isotherms of CH4 and N2 higher than critical temperatures on K02 activated carbon were measured with the volumetric method The pressure and temperature ranges were 0~12 MPa and 273~333 K respectively. A model, which took into account the adsorbate properties above critical temperatures and the adsorbent surface heterogeneity by pore size distribution, was proposed in this paper to predict the equilibrium data only using one adsorption isotherm. The gamma distribution was adopted to express the pore size distribution of the activated carbon, and the adsorption potential was calculated bythe 10-4-3 equation for slit shape micro pores. The relationships between the adsorbate density, the saturated adsorption amount and the equilibrium temperature have been discussed in detail. Through this method, the experimental adsorption data of CH4 and N2 were compared with the prediction equilibria. The study illustrates that the predicting method could present the adsorption equilibria accurately in the whole research range. And the mean relative deviations of the prediction of CH4 and N2 are only about 1.9% and 2.9%. This proves that the analyses of the adsorbate properties are reasonable. Inaddition, the model was applied to calculating the equilibrium data of various supercritical adsorption systems published in literatures. Despite different adsorbents and equilibriaconditions, the investigation results demonstrate that the suggested model performs well in predicting the gases adsorption equilibrium data with all mean relatived eviations less than 6.8%. Therefore, the model could be utilized to calculate the gases adsorption equilibrium data above critical temperatures in a wide range.
The photo catalytic degradation of activated red in the aqueous solution was studied using TiO2 supported on air electrode and active carbon (AC) as photo catalysts. It was found that the photo catalytic reaction rate of TiO2 was obviously increased by the presence of air electrode and AC supported. The air electrode which has functions of synthesizing H2O2 in situ and photocatalysis was reported. The results also implied that biasing of the electrode at +0.5V led to efficient charge separation. The current density of air (oxygen) electrode had effect on the oxidation rate of azo dye molecule, i=15 mA/cm2, and the rate could reach maximum. With AC mass fraction of about 21% the oxidation rate for TiO2/AC was obviously larger than that for TiO2, but the result was contrary to this for higher AC mass fraction (>30%). The experiment results showed that because TiO2 was supported on active carbon, the effective surface area of the photo catalysis and their absorbability for organic molecules can be increased. The pH in solution had effect on the oxidation rate of organic molecules.
The formation process of spindle 2-FeOOH particles obtained through the hydrolysis of FeCl3 solutions has been investigated by means of TEM and XRD. The effect of surfactant-Hexadecyl trimethyl ammonium bromide(CTAB) on this process has also been studied. The results show that growth of the needle-like pre-particles is based on the aggregation process, when there is no CTAB in the FeCl3 solution. Once CTAB was added, [2-FeOOH] nuclies would grow up through the diffusion mechanism. The2-FeOOH particles were smaller and uniform under the effect of CTAB. The spindle and needle-like 2-FeOOH particles with different axis ratios can be synthesized by controlling the reaction parameters such as the concentration of the original FeCl3 solution and aging temperature.
Surface modified silver nano particles were synthesized in a mixture solvent of water-alcohol with Pyridinium di-n-octadecyldithio phosphate(PyDDP) as a modification agent. Themorphology and structure of DDP-coated Ag (Ag-DDP) nanoparticles were characterized using X-ray powder diffraction(XRD), Transmission electron microscopy(TEM), Fourier transform infrared spectrum (FT-IR) and Thermo gravimetric analysis(TGA). Anti wear properties of Ag-DDP nano particles were tested using a four-ball tribological testing machine. The disperse properties of Ag-DDP nanoparticles were evaluated in solvents such as chloroform, benzen, toluene, liquid paraffin, distilled water and ethanol. The results show that Ag-DDP nanoparticles disperse in organic solvents, but they don’t disperse in water or ethanol. The good disperse properties in organic solvents enable Ag-DDP nanoparticles to be used as oil additives. The XRD pattern of Ag-DDP nanoparticles indicates that they have fcc crystal structure, and the modification layer can prevent the oxidation of Ag nanocores. TEM graphs show that Ag-DDP nanoparticles have a homogeneous grain distribution; the average diameter is about 15nm. FT-IR and TGA curves indicate that the existence of modification layer can prevent the adsorption of water on the surface of nanoparticles. Tribological tests show that Ag-DDP nanoparticles have good anti-wear properties in liquid paraffin, and they can improve the applied load of base oil.
The thermal decomposition characteristics of general ammonium perchlorate (g-AP) influenced by the addition of aluminum, nickel with different particle sizes (general and nano) are studied by TG and DSC. The results show that aluminum powders (both general and nano size) are nearly uninfluenced. Nano nickel powders have the greatest influence on the decomposition properties of g-AP among metal powders. Such accelerating effects of nanonickel powders are more apparent on the stage of high temperature decomposition than low temperature decomposition of g-AP and will be weakened with the decrease of the content of nanonickel. Nanonickel powders are also more effective than super fine nickel powders on accelerating the thermal decomposition of superfine AP (s-AP). The kinetic parameters of the thermal decomposition of s-AP and mixture of s-AP and nano nickel powders are obtained from the TG-DTG curves bythe integral method based on the Coats-Red fern equation. Nanonickel powders reduce the apparent activation energy of the thermal decomposition of s-AP from 157.9 kJ/mol to 134.9 kJ/mol. The most probable mechanism functions of the thermal decomposition reaction for s-AP and mixture of s-AP and nano nickel powders both belong to systems of Avrami-Erofeev equations. The mechanism of such accelerating effects has been discussed.
The Inorganic Fullerene-like MoS2 was obtained by a simple precipitation method using the polyethylenegly colas the dispersant,The hydroxylamine hydrochloride as the reductant, and (NH4)2S as the sulfursource. Themorphology and structure of the product were characterized by Powder X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and High-resolution Transmission Electron Microscopy (HRTEM). The results suggest that the polyethylene glycol dispersant can be adsorbed on the particle surface of the reaction precursor, amorphous MoS2 powders, to form a relative isolated environment. This isolated environment may induce an obstruct effect which helps the precursor nano-particles transfer to the IF structure in the subsequent calcinations process.
SiC single crystals have been prepared by the method of solvothermal synthesis with a system of SiCl4, CCl4 and metal K in an auto clave. X-ray diffraction (XRD), Raman spectra and transmission electron microscopy(TEM) were used to characterize the products. XRD reveals that the products are SiC crystals and TEM exhibits that SiC single crystal sofwires and platelets are obtained under different usages of metal K. The SiC wires have diameters of 10~20 nm and length up to 1.5μm; the platelets have lateral dimensions of 0.1~3 μm, exhibiting regular polygonal shapes and step-bunched side surface. Furthermore, the growth mechanism of the SiC single crystals is discussed and the effect of super saturation on the crystal growth and morphology is also investigated.
CdS and CdS/ZnS core-shell structure nano particles were synthesized in micro emulsion, and characterized by X-ray diffraction(XRD), transmission electron microscopy (TEM), UV absorption spectra and PL. The average diameter of CdS was about 3.3 nm, and CdS/ZnS core-shell structure was confirmed by XRD and UV. Considering the optical properties of CdS/ZnS core-shell structure nanoparticles which have different ZnS shell thickness, the UV absorption edge of CdS/ZnS becomes as lightred-shift with the thickness of ZnS layer increasing, and the absorption of shortwave band is strongly enhanced at the same time. The PL spectra indicate that ZnS shell layer can greatly eliminate surface defects of CdS nanoparticles and make its band-edge directed recombination increased, and the luminous efficiency of CdS is improved greatly when it has appropriate shell thickness.
PbS microstructures have several applications such as Pb2+ion-selective sensors and IR detector.The method to prepare PbS nanocrystal embed in poly(acrylicacid) (PAA) microstructures produced by means of soft lithography and solid state polymerizatio n by γ-ray irradiation was described. PbS micro patterns were prepared by Micro molding in Capillaries (MIMIC) with aqueous solution of acrylic acid lead monomer, and then solid state polymerized by γ-ray irradiation. Finally, the sample was treated with aqueous solution of Na2 Stoconvert the Pb2+ to PbS in the matrix. High-resolution micro structures of PAA, which have PbS nanocrystals embedded in them, could be produced successfully in this way. The final products were characterized by TEM, XRD, and XPS. TEM image indicated that the PbS particles embedded in PAA had a diameter of smaller than 20nm. X-ray powder diffraction method was also used to characterize the PbS/PAA nanocomposite film. The XPS analysis showed the element Pb has been converted to PbS nanoparticles in the composite films.
The preparation of Ag nanoparticles with the non-spherical shape has been conducted from aqueous solution by photo induced conversion. Ag nanoprisms (80~120nm) and nanocube s(90~200nm) were respectively obtained in the presence of trisodiumcitrate (TSC) orpolyvinylpirrolidon (PVP). These Ag nanoparticles were single-crystals. The results showed that Ag nanoprisms had apreferential growth direction along the Ag(111) axis and Ag nanocubes had a preferential growth direction along the Ag(100) axis. By means of characterization with TEM, ED and UV-V is Spectra, the fundamental analyses and discussion about the changing causes of nanoparticles shape from spherical tonon-spherical have been carried out in the photo induced process.
To understand the influence of impurities and rare earth elements in nature on the intergranular corrosion of the zinc-aluminum alloys, taking efficient methods to retard the inter granular corrosion, the atomic cluster of α phase grain boundary including impurities (Pb, Sn, Cd), rare earth elements (La, Y) and phase grain was constructed by computer programming based on the coincidence-site lattice theory. The recursion method was used to calculate the charge transfer over the grain boundary of α phase, and discuss influence of impurities (Pb, Sn, Cd) and Rare Earth elements (La, Y) on the electrode-potential of Zn and Al. The results shows that impurity elements (Pb, Sn, Cd) can increase the charge transfer between atoms over the grain boundary, leading to the large difference of electrode-potential between Zn and Al. Therefore the eroding is speeding up, but the RE element can reduce the charge transfer between atom sover the grain boundary, and lower the difference of electrode-potential between Zn and Al. Thus RE element is of the role of restraining the inter granular corrosion of zinc-aluminum alloys.
With a high-resolution 1H-NMR the features of solution-SBRs chain structures have been analyzed and made quantitative calculations of the chemical composites, inparticular, the contents of butadiene isomers have been made. It is reveal that the Bayer solution-SBR, whose performance is highly recognized inthe tire industry, has a high content of cis-1,4 butadiene isomers, allow content of trans-1,4 butadiene isomers, and a medium contents of 1,2add butadiene isomers and styrene units, as well as that the butadiene isomers display orderly characteristics in the sequence. The above structural features determine that Bayer solution-SBR can play good role in the balance of the low heat building up, antiwetskip and antiwear properties of green tire.