Effect Of Copper Oxide Research Articles

The effect of copper oxides on the curing of brominated epoxy resins

The kinetics of the curing of the brominated epoxy resin/dicyandiamide (DICY) system in the presence of copper oxides was investigated by isothermal differential scanning calorimetry (DSC). In essence, the heat of curing of brominated epoxy resins increases with increasing temperature as a result of the decrease in unreacted residual DICY at high temperature. The addition of small amounts of CuO and Cu 2O to the resins results in an increase in unreacted DICY left in the cured resins. Preferential adsorption of DICY on copper oxides is responsible for this difference. However, the amounts of unreacted DICY can be decreased by adding 2-methylimidazole (2-MI) to the resins. From large differences in enthalpy values and reaction orders but relatively unchanged T g values among various specimens obtained during curing of brominated epoxy/DICY/2-MI, it can be established that the system during curing could involve complex competing reaction mechanisms which cannot be described with a simple mathematical expression.

Effect of copper oxides on the thermal oxidative degradation of the epoxy resin

AbstractThe effect of copper oxides on the thermal oxidative degradation of a brominated epoxy resin–dicyandiamide system was studied using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The addition of small amounts of Cu2O or CuO fillers to the epoxy resins affected the relative amounts of highly reacted cyclic species formed during thermal aging and induced catalytic degradation of the epoxy resins. The overall and initial activation energies of the degradation process were found to decrease, and the order in the degradation kinetics of the epoxy resin changed from a near zero order to negative domain (autocatalytic nature) in the presence of copper oxides. © 1994 John Wiley & Sons, Inc.

Lattice effects on de Haas-van Alphen oscillations in strongly correlated systems.

We investigate the influence of a periodic potential and electron-phonon interactions on the de Haas-van Alphen (dHvA) effect in the presence of very strong Coulomb correlations. The inclusion of these correlations is essential for creating the insulating state at half-filling. We use the almost localized Fermi-liquid approach to include the Coulomb correlation induced metal-insulator transition at half-filling and to calculate the correlation effects within the context of renormalized band structures. The effects of a periodic potential on the electronic motion in a magnetic field are calculated by using a series of magnetic subbands called the Hofstadter spectrum. In contrast to Landau levels, these magnetic subbands have nonlinear field dependence and have nonuniform energy gaps between two adjacent subbands. The results of these differences appear as the field and the hole doping concentration x, dependence on the effective mass, chemical potential, and magnetization in two dimensions. The inclusion of strong Coulomb correlations leads to a substantial reduction in the electron-phonon coupling constant near the metal-insulator transition. Electron-phonon interactions are screened in the presence of strong Coulomb correlations because charge fluctuations are progressively suppressed by the correlation effects as half-filling is approached. Hence, the coupling constant decreases as x decreases. The screened coupling constant is estimated self-consistently by including the contributions from both the renormalized band and the dynamical screening effects. We show that both a periodic potential and electron-phonon interactions lead to mass enhancement as a function of x, thereby, changing both the amplitude and frequency of the dHvA oscillations. We discuss the feasibility of observing these effects in copper oxides.

Effect of copper oxide on the catalytic activity of iron-chromia catalyst for water gas shift reaction

It has been established that copper oxide promotes the catalytic activity of iron-chromia catalyst in the water gas shift reaction due to the formation of catalytically active aggregates. However, due to their gradual recrystallization and sintering into larger copper particles, the promoting effect sharply decreases.

The Use of Thermal Analysis Methods for the Estimation of Thermal Life Ratings of Magnet Wire Enamels

An empirical correlation between thermal analysis data and ASTM D-2307 results for magnet wire enamels is presented. This correlation was sought as an aid in rapid screening of experimental wire enamels and was not intended as a replacement for the ASTM test. Correlation testing was carried out on a variety of commercial and experimental enamels on copper wire in air, nitrogen, oxygen, wet oxygen, and R-22 refrigerant via thermogravimetry (TG) and differential thermal analysis (DTA). Wet oxygen and R-22 damaged the test equipment and so were not used for the complete spectrum of enamels. The best correlations were obtained in air. Reproducibility studies were carried out on samples from six different production runs of each of two enamels. The reproducibility was sufficiently good to allow identification of serious changes in enamel formulation. Variations of the correlations versus wirecuring speed (factor of two) were found to be within the reproducibility limits. The best correlations were derived from least squares plots which exclude thermal analysis results for the highest temperature enamels (polyimides). Preliminary experiments on the effects of copper oxides on thermal analysis data for polyimides indicate that such testing yields data giving a better fit to the correlation curve.

Becquerel's Effect of Copper Oxide in Alkaline Solution. II

Becquerel's Effect of Copper Oxide in Alkaline Solution. II