A density functional study on dielectric properties of acrylic acid grafted polypropylene.

Influence of acrylic acid grafting of isotactic polypropylene on the dielectric properties of the polymer is investigated using density functional theory (DFT) calculations, both in the molecular modeling and three-dimensional (3D) bulk periodic system frameworks. In our molecular modeling calculations, polarizability volume, and polarizability volume per mass which reflects the permittivity of the polymer, as well as the HOMO-LUMO gap, one of the important measures indicating the electrical breakdown voltage strength, were examined for oligomers with various chain lengths and carboxyl mixture ratios. When a polypropylene oligomer is grafted with carboxyl groups (cf.

Feasibility of density functional methods to predict dielectric properties of polymers.

Feasibility of density functional theory (DFT) to predict dielectric properties such as polarizability of saturated polymers is investigated. Small saturated molecules, methane and propane, which is a monomer of polypropylene chain, are used in testing the methods. Results for polarizabilities based on several density functionals together with different basis sets are compared and contrasted with each other, with results by Hartree-Fock and second-order Moller-Plesset perturbation theory, as well as experimental data.

Dipolar excitations at the LIII x-ray absorption edges of the heavy rare-earth metals.

We report measured dipolar asymmetry ratios at the LIII edges of the heavy rare-earth metals. The results are compared with a first-principles calculation and excellent agreement is found. A simple model of the scattering is developed, enabling us to reinterpret the resonant x-ray scattering in these materials and to identify the peaks in the asymmetry ratios with features in the spin and orbital moment densities.

Age and microdistribution of 210Pb at caribou bone surfaces measured by repeated alpha spectroscopy of 210Po.

Purpose: To measure microdistibution and age of 210Pb in Canadian caribou bone, and assess the accuracy of ICRP biokinetic and dosimetric models for 210Pb-supported 210Po at bone surfaces.

Materials And Methods: The previously described use of alpha spectroscopy to study 210Pb microdistribution at bone surfaces was expanded in a study of femora from 23 caribou. A new technique for measuring the age in vivo of Pb in bone, on the basis of the ratio of 210Po/210Pb activity, was carried out on eight caribou femora.