A study on UV-curable coatings for HD-DVD: Primer and top coats

This study relates to the development of coatings for optical discs in high-density digital versatile disc systems (HD-DVD or blue lay disk) that use a high numerical aperture of 0.85 at 405 nm wavelength and have a protective top layer over a primer layer for protection against damage and dust. Ultraviolet-curable raw materials of two acrylic monofunctional monomers ( isobornylacrylate, IBA and tetrahydrofurfurylacrylate, THFA) and two kinds of urethaneacrylate oligomers (OUMD and OUME) have been easily mixed with photoinitiators. Curing rate of these materials was characterized by FT-IR. In case of top coats, VTES (vinyltriethoxysilane) and acrylic acid were added to enhance the abrasion resistance. These two kinds of UV-curable resinous materials having no solvent were synthesized and investigated as means for making a blue ray disk having good optical and mechanical properties. In addition, dynamic characteristics including reflectivity, fluctuation of RF signal and noise level were also investigated.     

Magnetization reversal of a double-layer exchange-coupled ferromagnetic film

A theoretical investigation of magnetization reversal of a double-layer magnetic film with an easy-plane and easy-axis anisotropy has been performed. An analytical expression for the magnetization distribution in the layers in the presence of a magnetic field has been obtained. The calculations performed on the basis of the analytical relationships obtained show that when the thickness of the layers is close to the width of a magnetic inhomogeneity, it substantially affects the magnitude of the critical field for the magnetization reversal of the sample and the shape of the magnetization curve. It is also shown that a decrease in the exchange coupling between the layers leads to an increase in the magnitude of the critical field of magnetization reversal.     

Synthesis and characterization of new functional poly(urethane‐imide) crosslinked networks

To synthesize new functional poly(urethane‐imide) crosslinked networks, soluble polyimide from 2,2′‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride, 4,4′‐oxydianiline, and maleic anhydride and polyurethane prepolymer from polycaprolactone diol, tolylene 2,4‐diisocyanate and hydroxyl ethyl acrylate were prepared. Poly(urethane‐imide) thin films were finally prepared by the reaction between maleimide end‐capped soluble polyimide (PI) and acrylate end‐capped polyurethane (PU). The effect of polyurethane content on dielectric constant, residual stress, morphology, thermal property, and mechanical property was studied by FTIR, prism coupler, Thin Film Stress Analyzer (TFSA), XRD, TGA, DMTA, and Nano‐indentation. Dielectric constant of poly(urethane‐imide) thin films (2.39–2.45) was lower than that of pure polyimide (2.46). Especially, poly(urethane‐imide) thin films with 50% of PU showed lower dielectric constant than other poly(urethane‐imide) thin films did. Lower residual stress and slope in cooling curve were achieved in higher PU content. Compared to typical polyurethane, poly(urethane‐imide) thin films exhibited better thermal stability due to the presence of the imide groups. The glass transition temperature, modulus, and hardness decreased with increase in the flexible PU content even though elongation and thermal expansion coefficient increased. Finally, poly(urethane‐imide) thin films with low residual stress and dielectric constant, which are strongly affected by the morphological structure, chain mobility, and modulus, can be suggested to apply for electronic devices by variation of PU. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 113–123, 2006     

High-frequency properties of two-layer exchange-coupled ferromagnetic structures

A numerical study of peculiarities of ferromagnetic resonance (FMR) in a two-layer exchange-coupled ferromagnetic structure has been performed at various magnitudes and directions of an external magnetic field. The layers have a finite thickness and are characterized by an anisotropy of the easy-plane or easy-axis type. The FMR frequencies have been found to decrease relative to the frequencies calculated in the model of an infinitely thin film. It has been demonstrated that with an increase in the layer thickness the direction of the displacement of the lower FMR mode depends on the magnitude and direction of the external magnetic field and that the frequency of the higher mode decreases at any direction of the external field. The amplitudes of the resonance curves decrease with increasing magnetic field, with the ratio of the half-width of the resonance curve to the resonance frequency decreasing up to the saturation point, after which this parameter varies only slightly. The FMR frequencies have been studied as a function of the constant of the interlayer exchange interaction for fields located in the saturation region.     

Proton-conducting nanocomposite membranes based on P(VDF-co-CTFE)-g-PSSA graft copolymer and TiO2-PSSA nanoparticles

Bifunctional TiO₂ nanoparticles with hygroscopic and proton-conductive properties were synthesized by grafting proton-conducting polymer, i.e. poly(styrene sulfonic acid) (PSSA) from TiO₂ nanoparitlces via surface-initiated atom transfer radical polymerization (ATRP). These bifunctional TiO₂-PSSA nanoparticles were blended with poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(styrene sulfonic acid), i.e. P(VDF-co-CTFE)-g-PSSA to give proton-conducting membranes for high temperature fuel cells. FT-IR, UV-visible spectroscopy and X-ray diffraction (XRD) results revealed bifunctional properties of TiO₂-PSSA nanoparticles due to successful grafting of PSSA chains. Ion exchange capacity (IEC) of P(VDF-co-CTFE)-g-PSSA/TiO₂-PSSA membranes was not significantly changed irrespective of TiO₂-PSSA concentrations, representing almost fixed SO₃⁻ concentration in the membranes. In contrast, water uptake and proton conductivity of membranes continuously increased with increasing TiO₂-PSSA concentrations, presumably due to hygroscopic, soft conducting property of nanoparticles. The results of thermal gravimetric analysis (TGA) also showed that all the membranes were stable at least up to 280 °C.     

Investigation of MEA degradation in PEM fuel cell by on/off cyclic operation under different humid conditions

The durability of PEM fuel cells as a function of different humid conditions and MEA degradation were investigated by on/off cyclic operation. The maximum numbers of cycles determined by cycle at 10% of cell voltage loss were 1980, 1650, 1100, 520, and 320 cycles at relative humidity (RH) of 1000, 80, 50, 30, and 10%, respectively. The increases of ohmic resistance were observed at the high humid conditions of RH 100 and 80%. On the other hand, the charge transfer resistance increased at low humid conditions of RH 50, 30, and 10%. The losses of electrochemical surface area were obtained about 21% and 7% under RH 50 and 30% after the on/off cyclic operations, respectively. The thickness of electrode was reduced in the both anode and cathode layer, indicating that carbon corrosion occurred during on/off cycling. At cathode layer, the growth and migration platinum particles into polymer electrolyte were detected by XRD and TEM analyses.     

Resonance modes of two-layer exchange-coupled ferromagnetic film

Ferromagnetic and spin-wave resonances in two-layer exchange-coupled ferromagnetic films have been investigated numerically at different intensities of a magnetic field when it is directed in parallel or perpendicular to the film plane. Layers of the film have finite thicknesses and possess anisotropy of the easy-plane and easyaxis types. It has been shown that at a nonzero parameter of interlayer exchange coupling the dynamic component of magnetization upon ferromagnetic resonance is distributed nonuniformly across the film thickness. Its change has been described when the external magnetic field decreases from the saturating field to zero.     

Details of transporting and packaging semiliquid products

Details of the pipeline transporting and packaging of semiliquid products whose viscosity depends largely on temperature are considered. The type of liquid product used in our investigation is honey, pumped along the product pipeline of an ALB165 automated prepackaging and packaging line. The physical characteristics of honey are analyzed with allowance for temperature, and the effect of the product??s viscosity on the energy characteristics of the pump installed in the product pipeline is assessed. Our work is of value to specialists in the pipeline transporting and automated processing of semiliquid products.