Investigation of Degradation Behavior of Polymer on Surface of Film Due to the Existence of Monochromatic X-ray

Degradation and its temperature dependence of poly(methyl methacrylate) (PMMA) in the blend film of PMMA/SAN were investigated via ire-situ X-ray photoelectron spectroscopy(XPS). The results show that thermal degradation of PMMA takes place at 185, 130, 80 degrees C and even room temperature due to the existence of monochromatic X-ray. Furthermore, the degradation rate depends crucially on the experiment temperature.

Molecular weight dependence of phase Behavior of PEO/P(EO-b-DMS) blends: Application of Sanchez-Lacombe lattice fluid theory

Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide-block-dimethylsiloxane) (P(EO-b-DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO-b-DMS) blends were obtained by turbidity method. Based on Sanchez-Lacombe lattice fluid theory (SLLFT), the adjustable parameter, epsilon*(12)/k (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced.

Pressure effects on thermodynamics of phase behavior in polystyrene/methylcyclohexane solutions

The calculations presented in this paper are based on the Sanchez-Lacombe (SL) lattice fluid theory. The interaction energy parameter, g*(12)/k, required in this approach was obtained by fitting the cloud points of polystyrene (PS) /methyleyclohexane (MCH) polymer solutions under pressure. The SL lattice fluid theory was used to calculate the spinodals, the binodals, and the Flory-Huggins (FH) interaction parameter of the solutions. The calculated results show that the SL lattice fluid theory can describe the dependences of thermodynamics of PS/MCH solutions on temperature and pressure very well. However, the calculated enthalpy and the excess volume changes indicate that the Clausius-Clapeyron equation cannot be suitable to describe pressure effect on PS/MCH solutions. Further analysis on the thermodynamics of this system under pressure shows that the role of entropy is more important than the excess volume in the present case.

Thermodynamics of phase behavior in PEO/P(EO-b-DMS) homopolymer and block co-oligomer mixtures under pressure

The cloud-point temperatures (T-cl's) of poly(ethylene oxide) (PEO) and poly(ethylene oxide)-block-polydimethylsiloxane (P(EO-b-DMS)) homopolymer and block-oligomer mixtures were determined by turbidity measurements over a range of temperatures (105 to 130degrees), pressures (1 to 800 bar), and compositions (10-40 wt.-% PEO). The system phase separates upon cooling and T-cl was found to decrease with an increase in pressure for a constant composition. In the absence of special effects, this finding indicates negative excess volumes. Special attention was paid to the demixing temperatures as a function of the pressure for the different polymer mixtures and the plots in the T-phi plane (where phi signifies volume fractions). The cloud-point curves of the polymer mixture under pressures were observed for different compositions. The Sanchez-Lacombe (SL) lattice fluid theory was used to calculate the spinodals, the binodals, the Flory-Huggins (FH) interaction parameter, the enthalphy of mixing, and the volume changes of mixing. The calculated results show that modified P(EO-b-DMS) scaling parameters with the new combining rules can describe the thermodynamics of the PEO/P(EO-b-DMS) system well with the SL theory.

Study of PVT behavior of biaxially oriented polypropylene resins in the melting state

The PVT data of five kinds of biaxially oriented polypropylene (BOPP) Resins was measured by the PVT-100 apparatus. Thermal expansion coefficients (alpha) and isothermal compressibility (beta) were evaluated from Tait equation in the melting state and then compared with those fitted with the value of experiment. The results showed that it was reasonable to calculate alpha and beta with Tait equation in the melting state. At the same time, it was found that thermal expansion coefficients, isothermal compressibility and the melting temperature (T-m) of one of BOPP melts (S28C) were lower than those of the others in the same test conditions, indicating that the volume deformation of S28C resin is' less so that it could be realized to avoid arising surface defects of the film (biaxially oriented polypropylene film) due to. contracting, thereby decrease damage to the film in the subsequence process. Accordingly superior processing properties of S28C resin are confirmed from PVT. speciality.

Monte Carlo simulation of phase behavior of polymer blends with special interactions

Full Paper: The phase, behavior of A-B-random copolymer/C-homopolymer, blends with special interaction was studied by a. Monte, Carlo simulation in two dimensions. The interaction between I segment A and segment C was repulsive, whereas it was attractive between segment B and segment C. The simulation results showed that the blend became two large co-continuous phase domains at lower segment-B component compositions, indicating that the blend showed spinodal decomposition. With an increase of the segment-B component, the miscibility between the copolymer,and the polymer was gradually improved up to being miscible. In addition, it was found that segment B tended to move to the surface of the copolymer phase in the case of a lower component of segment B. On the other hand, if was observed that the average, end-to-end distances ((h) over bar) for both copolymer and polymer changed slowly with increasing segment-B component of the copolymer up to 40%, thereafter they increased considerably with increasing segment B component. Moreover, it was found that the (h) over bar of the copolymer was obviously shorter than that of the homopolymer for the segment-B composition, region from 0% to 80%. Finally, a, phase diagram showing I phase and - II phase regions under the condition of constant-temperature is presented.

Study of electrochemical behavior of ergosterol by in situ thin layer circular dichroic spectroelectrochemistry

The electroxidation of ergosterol was studied by in situ circular dichroic (CD) spectroelectrochemistry with a long optical path length thin layer cell. It was confirmed that the oxidation of ergosterol in ethanol solution is a two-electron irreversible electrochemical process with strong adsorption of an electroinactive product at the glassy carbon electrode, which blocks the electrochemical reaction. The CD spectroelectrochemical data were treated by the double logarithm method together with nonlinear regression, from which the formal potential, E-0 = 1.00 V, alpha n(alpha) = 0.302, the standard electrochemical rate constant, k(0) = 6.1(+/-0.4) x 10(-4) cm s(-1) and the adsorption constant, beta = 19 +/- 1, were obtained. The number of electrons transferred (n = 1.86) was estimated by cyclic voltammetry.

COMPARISON OF THE BEHAVIOR OF CYCLIC AND LINEAR POLYSTYRENE IN DILUTE-SOLUTION

Using a low angle laser light scattering photometer, the second virial coefficients (A2) of both cyclic and linear polystyrene were determined in cyclohexane, toluene and methyl ethyl ketone (MEK) solutions. From the data obtained in cyclohexane solution the theta-temperature of cyclic polystyrene was determined to be 30-degrees-C. In toluene solution A2 of cyclic polystyrene is smaller than that of linear polystyrene with the same molecular weight, but in MEK the values are similar.

INVESTIGATION OF ELECTROCHEMICAL-BEHAVIOR OF ARS ON GC ELECTRODE BY SPECTROELECTROCHEMISTRY WITH LOPTLC

The electrochemical behavior of Alizarin Red S(ARS) on GC electrode has been studied in acidic condition by spectroelectrochemistry with LOPTLC. It was found that there are three electrochemical reactions and followed by a chemical reaction of ARS in the potential range of 1.00——0.60V. The mechanism of electrode reactions has been studied and suggested based on the informations obtained from electrochemical and insitu spectroelectrochemical experiments.

Critical incident technique and explicitation interviewing in studies of information behavior

Urquhart, C., Light, A., Thomas, R., Barker, A., Yeoman, A., Cooper, J., Armstrong, C., Fenton, R., Lonsdale, R. & Spink, S. (2003). Critical incident technique and explicitation interviewing in studies of information behavior. Library and Information Science Research, 25(1), 63-88. Sponsorship: JISC (for JUSTEIS element)

The Iranian Foreign Policy in the Persian Gulf Region under the Rule of President Hassan Rouhani: Continuity of Change

Although Iran borders with many states and has direct access to the Caspian Sea as well as the Indian Ocean, the Persian Gulf region seems to be the most vital area to its security and prosperity. Yet since the 70’s Iran’s relations with the Arab states in the region have been rather strained and complex. The main reason for that had been the success of the Islamic revolution in 1979 which later resulted in a new dimension of Sunni-Shia rivalry. Moreover, post-revolutionary Iranian authorities also intended to maintain the regional hegemony from the Imperial State of Iran period. As a result, successive Iranian governments competed for hegemony in the Persian Gulf with the littoral Arab states which consolidated their regional positions due to close links and intensive cooperation with the West especially with the United States. Despite some political and economic initiatives which were undertaken by President Mahmoud Ahmadinejad, this rivalry was also evident between 2005–2013. The main aim of this article is to find out whether Iranian foreign policy towards the Arab states in the Persian Gulf region has undergone any significant changes since Hassan Rouhani became the President of the Islamic Republic of Iran in August 2013. According to Mohammad Reza Deshiri, the Iranian foreign policy after 1979 can be divided into so-called waves of idealism and realism. During dominance of idealism values and spirituality are more important than pragmatism while during the realistic waves political as well as economic interests prevail over spirituality. Iranian idealism is connected with export of revolutionary ideas, Shia dominance as well as the restoration of unity among all muslims (ummah). On this basis both presidential terms of Mahmoud Ahmadinejad can be classified as ‘waves of idealism’, albeit some of his ideas were very pragmatic. The question is if Hassan Rouhani’s foreign policy represents a continuity or a change. Is the current Iran’s foreign policy towards the Persian Gulf region idealistic or rather realistic? The main assumption is that there will be no Arab-Iranian rapprochement in the Persian Gulf without a prior normalization of political relations between Iran and the West especially the United States.

Peer rejection and social information-processing factors in the development of aggressive behavior problems in children.

The relation between social rejection and growth in antisocial behavior was investigated. In Study 1,259 boys and girls (34% African American) were followed from Grades 1 to 3 (ages 6-8 years) to Grades 5 to 7 (ages 10-12 years). Early peer rejection predicted growth in aggression. In Study 2,585 boys and girls (16% African American) were followed from kindergarten to Grade 3 (ages 5-8 years), and findings were replicated. Furthermore, early aggression moderated the effect of rejection, such that rejection exacerbated antisocial development only among children initially disposed toward aggression. In Study 3, social information-processing patterns measured in Study 1 were found to mediate partially the effect of early rejection on later aggression. In Study 4, processing patterns measured in Study 2 replicated the mediation effect. Findings are integrated into a recursive model of antisocial development.