Elastomeric electron beam-cured coatings: Structure–property relationships. I. Oligomer structure

Mechanical properties of electron beam-cured films were studied as a function of oligomer structure and monomer diluent. In films cast from polyester acrylourethane oligomers, increasing the chain length between the two acrylate groups on each end resulted in a decrease in breaking strength from 7000 psi to 1000 psi in Young's modulus from 200,000 psi to 700 psi, and in glass transition temperature from 50 to ?25°C, while the ultimate elongation increased from 20% to 210%. These properties were virtually independent of dose above 1 Mrad. The elongations were compared with literature values at equivalent degrees of crosslinking and found to fall within the range, but on the low elongation side of the distribution. It was speculated that the crosslinks' functionality would equal the average degree of polymerization of the double bond at each end of the oligomer, resulting in multirayed, star-shaped crosslinks with less flexibility than those with the usual functionality of 3 or 4, and methods for reducing this functionality were investigated. Addition of active monomers effected only minor change, but diethylaminoethyl acrylate was found to be very helpful in increasing the extensibility of these films considerably. This behavior can be explained by assuming that this monomer has a significant chain transfer constant, which should reduce the degree of polymerization of acrylic endgroups, producing a looser structure.     

Fabrication of reverse‐osmosis membranes for the desalination of underground water via the γ‐radiation grafting of acrylic acid onto polyethylene films

Research has been devoted to the desalination of saline water to fresh water suitable for human demands because of the shortage of water in some countries. Therefore, in this study, reverse‐osmosis membranes were prepared via the γ‐radiation graft copolymerization of acrylic acid onto high‐density and low‐density polyethylene. The factors that could affect the grafting process, such as the solvent type, monomer and inhibitor concentration, and irradiation dose, were investigated to determine the optimum conditions for radiation grafting. The polyethylene grafted acrylic acid copolymers (PAAc‐g‐PE) graft copolymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical, rheological, and thermal property testing to illustrate the possibility of practical use in water desalination. The prepared grafted membranes showed significant results in the reverse‐osmosis desalination method with underground saline water. The factors affecting the desalination of water, such as the water flux, operation time, and grafting percentage, were studied. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45410.     

N‐phenyl‐3‐substituted 5‐pyrazolone derivatives as organic stabilizers for rigid poly(vinyl chloride) against photodegradation

N‐Phenyl‐3‐substituted 5‐pyrazolone derivatives were investigated as organic photostabilizers for rigid poly(vinyl chloride) (PVC). Their stabilizing efficiency was evaluated by the determination of the weight loss of the polymer after irradiation for different periods and by the determination of the amount of gel formation as well as the intrinsic viscosity of the soluble fraction of the degraded polymer. Moreover, the efficiency was evaluated from the extent of the discoloration of the degraded polymer. This was attributed not only to the radical trapping potency of the pyrazolone derivatives, which intervened with the radical degradation species in the degradation process of PVC, but also to the blocking of the newly formed radical sites on the polymeric chains. Their stabilizing efficiencies were compared with those of phenyl salicylate and 2‐hydroxy‐4‐(octyloxy)phenyl benzophenone, industrially known UV absorbers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1543–1555, 2006     

D.C. conduction phenomenon and spectrum of a novel bis(7-formyl-8-hydroxyquinoline) zinc complex

A novel bis(7-formyl-8-hydroxyquinoline)zinc complex was prepared from 7-formyl-8-hydroxyquinoline. This compound was characterized on the basis of elemental analysis, i.r., ¹H nuclear magnetic resonance, magnetic moment and conductivity measurements. The compound was a non-conductor in dimethylformamide. A tentative structure for this compound is suggested. The electrical conductivity at various temperatures for an annealing time of 1 h has been measured. The activation energy of this compound is found to be 0.68 eV. Conduction parameters including the Schottky coefficient (_s), Schottky electrode barrier (_s), jump distance (d) and dielectric constant () have been determined. The aim of this study is also to understand the mechanism of conduction of this zinc(II) complex.     

On Slow-Fading MIMO Systems With Nonseparable Correlation

In a frequency-selective slow-fading channel in a multiple-input multiple-output (MIMO) system, the channel matrix is of the form of a block matrix. A method is proposed to calculate the limit of the eigenvalue distribution of block matrices if the size of the blocks tends to infinity. Asymptotic eigenvalue distribution of is also calculated, where the entries of are jointly Gaussian, with a correlation of the form (where is fixed and does not increase with the size of the matrix). An operator-valued free probability approach is used to achieve this goal. Using this method, a system of equations is derived, which can be solved numerically to compute the desired eigenvalue distribution.