Diffusion of Particles Adsorbed on a Reconstructive Surface
The influence of surface reconstruction on diffusion of particles, adsorbed on the surface, is investigated in the framework of symmetrical four-position model. The analytical expressions for the free energy and chemical and jump diffusion coefficients are obtained assuming the lateral interaction between the particles is negligibly small. The coverage dependencies of the tracer, jump and chemical diffusion coefficients are calculated using the expressions and MC simulations. The results demonstrate clearly a drastic change of the behavior of all diffusion coefficients on the reconstructed surface.
Surface diffusion of particles adsorbed on a lattice with two non-equivalent sites
Abstract We investigate the surface diffusion in a system of particles adsorbed on a lattice with two non-equivalent sites, whose number in the unit cell and adsorption energy are different. When the adsorption energies are comparable, the adparticle diffusion proceeds by uncorrelated adparticle jumps. In the opposite case, the adparticle migration proceeds by pairs of consecutive jumps. The contributions to the surface diffusion of these jump sequences depend considerably on the adparticle surface coverage and the relation between the adsorption energies.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.