bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of zirconium–niobium pressure tube surfaces for hydrogen using secondary ion mass spectrometry (SIMS)
Authors: McIntyre N. S. , Weisener C. G. , Davidson R. D. , Lennard W. N. , Massoumi G. R. , Mitchell I. V. , Brennenstuhl A. , Warr B.
Published: December 2004

Understanding the mechanisms of hydrogen ingress into pressure tubes fabricated from zirconium–2.5% (w/w) niobium alloy requires knowledge of the hydrogen concentration in the surface oxides, of the oxide/metal interface and in the alloy phase beneath the interface. Secondary ion mass spectrometry (SIMS) has attractive capabilities for detecting hydrogen isotopes in such surface films, but its quantitative response and spatial resolution are controversial for hydrogen because of the strong tendency for the element to migrate, owing to thermal and sputtering effects. High sputter rate conditions have been used here, which result in an improved capability to detect hydrogen in ZrNb alloy and ZrO2 down to concentrations of <2 × 1017 atoms cm−3 (<0.1 ppm, w/w). Quantitation of deuterium concentrations has been accomplished by SIMS calibrated using ion implants and, in some cases, verified by nuclear reaction analysis (NRA).
Effect of scattering processes on the spectra of electrons emitted from the surface of solids: Monte Carlo calculations
Authors: Špalek A.
Published: December 2004

Electron scatterings in the volume and at the surface of a solid are simulated by the Monte Carlo method. The effect on the electron distributions is demonstrated in some typical cases: aluminium, copper and gold covered with a carbonaceous layer.
A high energy resolution, high spatial resolution photoemission microscope
Authors: Knapp G. S. , Keenylside M. , Griffin C.
Published: December 2004

This paper will discuss a microscope that allows high energy resolution spectroscopy to be performed at high spatial resolution. This instrument uses a high magnetic field to contain and focus electrons emitted from the sample surface and has a two‐dimensional detector that records a photoelectron image. It is also equipped with a hemispherical analyzer, which allows state‐of‐the‐art spectroscopic performance to be obtained from very small areas. The instrument is unique in that it collects a much larger solid angle than any other instrument in use today, and spatial resolutions of 2 μm and energy resolutions of 0.25 eV have been achieved.
XPS analysis of thin chromium films
Authors: Petkov K. , Krastev V. , Marinova Ts.
Published: December 2004

The surface and mechanical properties of thin Cr films play an essential role in microphotolithographic processes in which an inorganic photoresist based on vacuum‐evaporated As2S3 is used as a light‐sensitive system. The present paper reports some XPS data about thin chromium layers obtained by thermal evaporation, high‐frequency sputtering, electron beam evaporation and de magnetron sputtering. A correlation is found between the surface elemental composition of the metal coating and the metal coating and the possibilities of obtaining good adhesion between the Cr and As2S3 used as the inorganic photoresist. It is shown that the presence of pure Cr on the surface of the samples is a defining condition for photolithography in the submicron region.
Photoemission applied to the in situ study of epitaxial growth: Theoretical modelling
Authors: Laamouri A. , Rouhani M. Djafari , Gue A. M. , Fazouan N. , Esteve D.
Published: December 2004

Reflection high‐energy electron diffraction oscillations are commonly used to monitor the growth of materials and to control the thickness as well as the roughness of the deposited layer.

A new technique based on the photoemission current has been employed by Eckstein et al.1 to study the dynamics of the epitaxial growth of GaAs by molecular beam epitaxy. In particular, they have observed oscillations in the energy‐integrated near‐threshold photo emission current that they attribute to periodic changes in the nature of the surface.

Our work deals with the physical origin of the observed photoemission oscillations during growth of GaAs. We assume that the photoemission properties depend on the chemical nature of the adsorbed atoms and on their local configurations. In this way, we have developed a theoretical model that associate a simple growth model with an atomic photoemission mechanism.

The photoemitted current calculated with this model exhibits the features observed experimentally which seem to be strongly dependent on the molecular As2 adsorption mechanisms and on the roughness of the growing layer.
Measurement of ion sputtering yields for depth profile analyses
Authors: Suzuki Toshiko , Hirokawa Kichinosuke , Fukuda Yasuo , Suzuki Ken‐ichi , Hashimoto Satoshi , Usuki Noriaki , Gennai Norio , Yoshida Shizuo , Koda Mitsuru , Sezaki Hiroshi , Horie Akira , Tanaka Akihiro , Ohtsubo Takashi
Published: December 2004

Results are reported of the second phase of joint research on ion sputtering that was conducted by the Iron and Steel Institute of Japan. Various effects on sputtering yields were studied in detail, and the yields for Ni and Zn were determined by analysing the depth profile of electrodeposited steel sheets with an Auger electorn spectrometer, Ar+ ions were used as the bombarding species, and a Faraday cup, which was fitted with a front plate incorporating a small hole in the centre for the ions to pass through, was used to measure the electric current of the incident ions. To calculate the ion current density, a correction for the effective transmittance efficiency of the hole was made according to its cross‐sectional shape. The sputtering yields determined in several laboratories by using this correction agreed with each other better than those obtained in the first phase of the work. The angular dependence and energy dependence of the sputtering yields for Ni and Zn were measured.

A standard procedure is proposed for the measurement of ion sputtering yields to analyse depth profiles, including methods to measure the ion current, to calculate the current density, to optimize the sample position and to tune lenses of the ion gun.
Chemical effect on the XPS spectra of the valence band and on O KLL and Pd MNN Auger spectra in pumice‐supported catalysts
Authors: Venezia A. M. , Duca D. , Floriano M. A. , Deganello G. , Rossi A.
Published: December 2004

X‐ray photoelectron spectra of the valence band and X‐ray‐excited O KLL Auger transition of pumice‐supported Pd and Pt catalysts have been obtained and compared to the corresponding spectra of pumice (a naturally occurring amorphous aluminosilicate). The changes observed indicate interaction between metal and support.

The valence region of the catalysts consists of three large peaks: one due to the d band of the metals and the other to the O 2p non‐bonding orbitals and bonding‐type orbitals formed by a mixing of the atomic orbitals (O 2p, Si 3s and Si 3p) of oxygen and silicon from the support. The intensity decrease of the component due to the bonding orbitals, observed in the catalyst spectra, suggests electron donation from the support to the metal.

The O KLL valence Auger spectra of pumice and of catalysts have been analysed. The changes in the Auger pattern are attributed to variations of the atomic orbital composition of the valence levels due to the presence of the supported metals.
Study of ion implantation and annealing effects in silicon wafers using high‐frequency phonon scattering
Authors: Strickland K. R. , Edwards S. C. , Wigmore J. K. , Collins R. A. , Jeynes C.
Published: December 2004

For the first time, high‐frequency phonon scattering has been used to study ion implantation damage in silicon wafers. Diffusive scattering of reflected heat pulses was found to be greatly increased by self implantation at a dose of 1015 cm−2, which is known to produce an amorphous layer. Subsequent low‐temperature (250°C) annealing produced a reduction in scattering which could be attributed to smoothing of the amorphous–crystalline (a–c) interface, i.e. to a reduction in the short‐wavelength components of the interface roughness.
Boumans' equation revisited. Part II: A new sputtering equation
Authors: Payling Richard
Published: December 2004

In Part II, a modified form of Boumans' equation for the sputtering rate in a Grimm‐style glow discharge lamp is presented

where q is the sputtering rate, CQ and V0 are matrix‐dependent constants, ig and Vg are the lamp current and voltage, respectively, and n ≈︁0.74. Previous work in support of the original equation is shown to be in error because this earlier work used a constant time for sputtering to measure the effect of varying current and voltage. This meant that sputtering rates were being recorded over widely varying depths. It is shown, in a Grimm‐style glow discharge lamp, that sputtering rate increases with depth. The new equation is supported by measurements on thin films and on bulk samples where the time has been varied to keep the depth nearly constant. The impact of the new equation on bulk analysis and quantitative depth profiling is also described.
Secondary ion mass spectrometry analysis of iron oxides with known 18O/16O contents
Authors: Lu Q. , Hultquist G. , Mathieu H. J. , Gopalakrishnan R. , Younes C.
Published: December 2004

Iron oxide films with known 18O and 16O content were prepared by thermal oxidation of iron metal in H218O/H216O gas mixtures at 400°C. The oxide films were analysed in four laboratories with SIMS within a month after they were produced. One oxide sample (with 91% 18O) was also analysed after storage in air for 15 months. It turns out that the oxides are stable over that time period. The yield ratios of the detected ionic species based on negative 18O and 16O ions and metal–oxygen‐containing ions were compared with the nominal, known values. The effect of interference of residual 16O and 16OH on the results is discussed and appropriate measures for reducing this effect are proposed. Reasonably good agreement is found between the four laboratories.
XPS and ISS studies on the interaction of H2S with polycrystalline Cu, Cu2O and CuO surfaces
Authors: Galtayries A. , Bonnelle J.‐P.
Published: December 2004

The first steps of H2S adsorption have been studied on polycrystalline copper samples, which are more relevant to industrial copper samples than to single‐crystal surfaces. The tools for characterization are ultrahigh vacuum spectroscopic methods, such as x‐ray photoelectron and ion scattering spectroscopies. The H2S adsorption on metallic copper and on the corresponding Cu2O and CuO oxides is dissociative and highly dependent on the chemical nature of the exposed surface rather than on the temperature, from room temperature up to 623 K. In our conditions, Cuo sulphidation deals with the top Cuo layer whereas two to three oxide surface monolayers are modified at H2S saturation. The results on oxides are interpreted by an oxygen/sulphur replacement mechanism following the dissociative adsorption. Contaminated copper surfaces by phenanthrene or H2O treatments are hardly sulphided. As far as surface reactivity is concerned, the adsorbed sulphide species have been shown to be quite strongly bound to the different surface states tested in this work: only oxidative treatments induce desorbing products at 623 K.
Quantitative methods for the characterization of the auger peaks of SrTiO3
Authors: Horvath G.
Published: December 2004

Segregated layers of heat‐treated single and polycrystalline SrTiO3 samples were investigated by Auger electron spectroscopy. Heat treatments were carried out in air, N2 and in 5% H2 + 95% N2 at 800°C. For evaluation of the detected signals, different quantification methods were applied. It is shown that a ‘first principle’ calculation without standards gives reliable results with a maximum relative error of 15%. Employing methods with standard samples, the usage of compound standards considerably improves the accuracy. The Palmberg formula with elemental standards has ∼100–120% relative error, while with a compound standard this value is ∼15%. The best result was obtained in the case of a compound standard with matrix factor correction, where the relative error was found to be 5–10%. However, in the case of segregated materials the crucial point is whether monolayer or multilayer segregation takes place.
Fluence, flux, current and current density measurement in faraday cups for surface analysis
Authors: Gilmore I. S. , Seah M. P.
Published: December 2004

The manufacture and design of ideal Faraday cups for measuring currents and current densities in electron and ion beams is well understood and yet laboratories can still report values for surface science parameters involving sputtering that diverge by a factor of two. This is because the constraints of space and lack of properly designed specimen stages lead to difficulties in cup design. We have designed, here, Faraday cups for current and current density measurements that are simple, compact and may be inserted into a surface analysis system on a normal sample stub without the need for special electrical feed‐throughs. The design parameters and operating conditions to achieve efficiencies demonstrated to be within 2% of the ideal behaviour are given in detail. The problems encountered in achieving this level of accuracy are discussed.
Laterally resolved chemical analysis of solid surfaces by laser‐SNMS
Authors: Berthold W. , Wucher A.
Published: December 2004

The prospects of laser‐based secondary neutral mass spectrometry (SNMS) as a technique for quantitative and fast imaging of the chemical composition of a solid surface are evaluated on a model sample consisting of different nickel grids pressed into a silver substrate. In the experiment, neutral atoms sputtered from the sample surface by a finely focused Ga+ ion beam are post‐ionized by non‐resonant two‐photon absorption from a pulsed 248 nm excimer laser and detected by a reflectron‐type time‐of‐flight spectrometer. Particular emphasis is put on the interrelation between image acquisition time and detection sensitivity. It is demonstrated that multiple mass images taken with only one single laser shot per pixel allow the safe detection of 0.1 at.% impurities at a lateral resolution of 1 μm, the total image acquisition time being only of the order of minutes. In order to convert the measured signals into element concentrations, a quantitation scheme is described that allows correction of the acquired images for influences of surface topography, fluctuations and drift of primary ion current, etc.
Determination of miller indices of side faces of small crystallites from scanning force microscopy angle measurements
Authors: Schwarz A. , Schwarz U. D. , Bluhm H. , Wiesendanger R.
Published: December 2004

The calculation of Miller indices from out‐of‐plane angle measurements with scanning force microscopy (SFM) is demonstrated on three different systems: rutile on haematite, rutile on sapphire and haematite on sapphire. The height of the investigated crystallites ranges from several millimetres (rutile on haematite) down to <10 nm (haematite on sapphire). General issues of goniometry by means of SFM, such as the influence of the scanner calibration, the adjustment of the feedback loop on the error involved in out‐of‐plane angle measurements and the limitation of SFM goniometry due to tip geometry, are discussed and a comparison with other methods are given.
Advances in the analysis of surfaces of biomedical interest
Authors: Ratner Buddy D.
Published: December 2004

Materials used in biomedical applications often function based upon their surface properties. Thus, understanding their surfaces is critical to the design and engineering of new biomaterials and medical devices. Modern surface analysis tools have been developed largely around the needs for the microelectronics and petrochemicals industries, where durable, inorganic surfaces are studied. This paper examines how surface analysis methods can be applied to biomaterials which are typically hydrated and fragile. In particular, vacuum compatibility, sample damage, the aqueous/solid interface; spatial information, buried interfaces, chemical complexity and correlation with bioreactivity will be addressed.
X‐ray photoelectron spectroscopic studies of carbon‐fiber surfaces. 19. Surface chemical changes during electrochemical oxidation in base
Authors: Weitzsacker Cara L. , Sherwood Peter M. A.
Published: December 2004

Electrochemical oxidation of polyacrylonitrile‐based carbon fibers in a basic electrolyte was studied and the surface chemical changes monitored by core and valence‐band x‐ray photoelectron studies. These studies show that potentionstatic treatment under strongly oxidizing conditions in a sodium hydroxide electrolyte for 20 min leads to a surface consisting of a substantial amount of weakly attached carbonate ions with a lesser contribution from carbosylae and other C/O groups attached to the carbon‐fibre surface.

The valence‐band spectrum for a carboxylated carbon fibre calculated by a multiple‐scattered wave Xα calculation on a CO2−−Substituted coronene (C36O) shows that a carboxylate‐functionalized carbon fiber would make only a partial contribution to the observed spectrum, which shows considerable similarities with the spectrum of the carbonate ion. The weakly attached carbonate ions were reduced in surface concentration by repeated washing.
Study of a zinc chloride in poly(ethylene glycol) layer on an aluminium oxide surface by inelastic electron tunneling spectroscopy
Authors: Line M. J. , Pritchard R. G. , Pynenburg R. , Latham R. J. , Linford R. G.
Published: December 2004

Inelastic electron tunneling spectroscopy is used to compare the adsorption onto aluminium oxide of poly(ethylene glycol) of relative molar mass 400 (PEG400) with poly(ethylene glycol) that has been coordinated with zinc chloride. This work carried out on a low‐molecular‐weight analogue of a polymer electrolyte reveals that the steric hinderance brought about by the coordination of zinc chloride with poly(ethylene glycol) changes the mechanism by which the polymer bonds to an aluminium oxide surface. The zinc bonds both to atmospheric water and to the ether oxygens in the polymer, which restricts the conformational freedom of the polymer. This restriction causes the attachment of the polymer to the aluminium oxide substrate to be primarily by hydrogen bonding, which reveals itself through the appearance of an extra peak in the inelastic electron tunneling spectrum at ∼440 meV. The implication is that when monolayer coatings of PEG400/ZnCl2 are adsorbed on aluminium oxide, the coordination of the zinc with the polymer imposes a structure upon the latter.
How to cope with new and proposed regulations affecting PVC additives: The right time for the right cadmium‐containing stabilizers
Authors: Kauder Otto S.
Published: December 2004

Stabilizers containing relatively toxic metals such as cadmium or lead have long been used whenever regulations permit because, on a cost‐performance basis, they have been far superior to available alternatives. Recent and proposed regulatory changes increase the regulatory compliance cost connected with the use of traditional products. Argus Chemical's efforts have approached the problem from several directions, including: 1) minimizing compliance cost by providing products less hazardous in use; for example, solid stabilizers with minimal dusting tendency, and liquid stabilizers able to replace solids; 2) upgrading performance by providing more efficient products; 3) providing products in which relatively toxic ingredients have been replaced by less toxic materials. Applications of these approaches in the specific areas of general‐purpose flexible calendering and extrusion compounds, vinyl plastisols, and phonograph record compounds will be described. The paper will also compare and contrast the regulatory status as it now exists in the U.S.A. with the situation currently prevailing in other world areas.
The influence of additives on the primary particle nucleation and agglomeration in poly(vinyl‐chloride)
Authors: Törnell Bertil E. , Uustalu Jaan M.
Published: December 2004

The formation and agglomeration of PVC primary particles were studied in bulk polymerization experiments. In the absence of additives, the primary particles started to agglomerate at low conversions. The agglomeration conversion, as well as the size of the agglomerated particles, decreased when the agitation speed increased. At the highest speed tested, the agglomeration started already at 0.05 percent conversion. The primary particle size was about 0.16‐0.18 μm, and seemed to be constant in the conversion interval studied (up to 5 percent). This indicated that the nucleation rate of primary particles was almost constant and that the growth rate of agglomerated particles was very low. The addition of sorbitan monolaurate produced a decrease in primary particle size. Polymeric additives such as PMMA, EVA, and PVAc stabilized primary particles against agglomeration but had no marked effect on the primary particle size. The monomer‐soluble fraction of poly(vnyl alcohol‐b‐vinyl acetate) with high content acetate groups did not affect either the particle size or the agglomeration process.
Classification of lubricants for PVC by compaction testing
Authors: Fahey Timothy E.
Published: December 2004

Compaction testing was used to classify 10 lubricants for PVC, spanning the range of chemical types. Lubricants are defined as internal or external by their effect on compaction on being added to a standard base formulation. The results show excellent correlation by chemical type, in which the lubricants are divided into three distinct categories—external lubricants: paraffin waxes and low‐density polyethylenes; intermediate lubricants: montanic ester waxes and bisstearmides; internal lubricants: glycerol and monostearate and fatty acid alcohols. A test is proposed by which new additives may be easily classified or present lubricant systems evaluated.
High damping poly (vinyl chloride)/polyurethane blends by tailoring the molecular structure of polycaprolactone‐based polyurethanes
Authors: Bandyopadhyay P. K. , Shaw M. T.
Published: December 2004

Because a blend of limited miscibility level produces high damping characteristics in a composite, copolyurethanes of different molecular structure were synthesized to achieve a desired level of miscibility in PVC. A study of the viscoelastic properties of blends of a 50‐to‐50 weight ratio of polyurethanes and PVC showed a steady decrease in miscibility on replacement of polyurethanes synthesized from polycaprolactone diols with a molecular weight of 2000, with polyurethanes synthesized by poly(ethylene oxide) diols, up to 80 mol percent, whereupon the polyurethanes became immiscible. The temperature range of damping for a particular polyurethane could be controlled by adjusting the ratio of PVC to the polyurethane. More polyurethane in the blend shifts the damping range toward lower temperature, and vice versa.
Characterization of selected pigments for exterior poly(vinyl chloride) applications
Authors: Mathur K. , Kramer K.
Published: December 2004

Pigments selected from the iron oxide, chromium oxide and furnace black families, which offer the possibility of preferred earthtone colors, were characterized for: their stability at PVC processing temperatures; their effect on long‐term ultraviolet exposure, and their infrared absorption properties that relate to heat buildup and buckling in the composite. This study has basically ranked the pigments into three categories in terms of their overall performance. Besides the earthtone color, the added economics of these pigments makes them of prime interest for external applications.
The chemical mechanisms of outdoor weathering in polyvinyl chloride
Authors: Summers James W. , Rabinovitch Elvira B.
Published: December 2004

Polyvinyl chloride weathering is a free radical mechanism started by absorption of energy sufficient to break chemical bonds. Absorption chromophores are often related to PVC heat history. Chemical bond energies are examined to indicate weak sites susceptible to initial degradation. Mechanisms of yellowing, oxidation, bleaching, and surface erosion are described. Some of the techniques for controlling the degradation of PVC are described. These techniques allow the PVC degradation to be controlled sufficiently so that PVC is accepted commercially as an excellent outdoor weathering material.
The all‐acrylic weatherable impact modifier for PVC
Authors: Rabinovic I. S.
Published: December 2004

Rigid poly (vinyl chloride), PVC, is finding increasing use in outdoor applications as a replacement for conventional materials such as wood, aluminum, steel, and other materials. Formulating PVC for outdoor applications requires special attention to several essential properties in order to achieve the high‐quality standards needed over a long period of time. One area that needs modification in a rigid PVC formulation for outdoor applications is toughness. Impact modifiers used to improve the toughness of PVC in outdoor use are CPE, EVA copolymers, and acrylates.

The all‐acrylic weatherable impact modifier is designed especially to modify PVC for outdoor use and ease of processability. We will review its key performance features with special emphasis on the processing advantages of the all‐acrylic impact modifier. The study of the influence of processing conditions on the physical performance of weatherable PVC compounds in a Ba/Cd stabilized window profile shows an acrylic modifier to give consistently high toughness over a wide temperature range and shearing friction.
Elimination of plate‐out problems in barium‐cadmium‐zinc stabilized poly(vinyl chloride) (PVC) wire coating compounds
Authors: Choi Jae Hong , Drexler Leonard H.
Published: December 2004

A laboratory two‐roll mill technique and chemical analysis procedures were used to determine the source of plate‐out problems associated with plasticized, barium‐cadmium‐zinc stabilized, poly(vinyl chloride) extrusion wire coating compounds. The results of this study indicated that the barium‐cadmium‐zinc heat stabilizer was the main contributor to the plate‐out problem. It was further shown that the plasticizer participated in the plate‐out process while a secondary heat stabilizer system did not. Using the two‐roll mill technique, it was possible to optimize the poly(vinyl chloride) compound to minimize plate‐out while maintaining optimum physical properties.
Stabilizer comparison exterior PVC profile applications
Authors: Weiler Robert G.
Published: December 2004

This paper compares the performance of Estertin mercaptide, alkyltin mercaptide, barium/cadmium carboxylate, inorganic lead, and organotin carboxylate PVC heat stabilizers for exterior PVC profile applications. These stabilizers were all evaluated for heat stability performance, exterior and accelerated weatherability, and lubrication and processability. Since their lubrication characteristics vary greatly, several formulation modifications were employed including European and U.S. types. While all stabilizers could be processed acceptably into exterior rigid profiles, with the possible exception of the tin carboxylate, the Estertin mercaptide and the alkyltin mercaptide exhibited fewer processing difficulties. The barium/cadmium carboxylate provided the best weatherability at low titanium dioxide loadings. At high titanium dioxide loadings, only small differences could be detected between all types of stabilizers evaluated.
Particle size analysis of plasticized PVC dispersion resins using the photometric centrifugal sedimentation method
Authors: Moran Michael T.
Published: December 2004

There are many known methods for determining the particle size distribution of PVC dispersion resins. Most of these methods require that the resin be in an aqueous medium. PVC dispersion resins are used primarily in a plasticizer medium. The shearing action that takes place when the resin is mixed in plasticizer and the subsequent solvating action of the plasticizer affect the particle size distribution of the dispersion resin. It is advantageous to be able to determine the particle size distribution of the plasticized resin since it can affect various properties such as rheology, gloss and foam quality. It is the purpose of this paper to show that a fast zonal sedimentation technique can be used to analyze the less than 20 μ particle size fraction of a dispersion resin after it has been mixed in a plasticizer system. This can be accomplished in less than 90 minutes. This technique can be used to relate particular dispersion resin properties to the particle size distribution of the resin. The method can also be used as a quality control test.
Some viscoelastic porperties of poly(vinyl chloride)/dioctyl phthalate systems
Authors: Santamaria A. , Muñoz M. E. , Peña J. J.
Published: December 2004

The viscosty and the recoverable shear compliance of poly(viny chloride)/dioctyl phthalate systems are studied at different temperatures and concentrations. The recoverable shear compliance is determined by the method of the stress relaxation after cessation of flow in a Couette flow viscosimeter. The results show the existence of a concentration dependent critical temperature Tc which separates two different flow regions.
A scientific approach to rigid poly(vinyl chloride) extrusion
Authors: Summers James W. , Rabinovitch Elvira B. , Quisenberry Joseph G.
Published: December 2004

Although rigid PVC has been extruded for many decades, more recent scientific evidence on primary particle flow units, crystalline structure, melting and recrystallization, transition from melt fracture to viscous flow, and differences in shear history between cubes and powder help to understand PVC extrusion. This understanding can replace some of the art of PVC extrusion with science. In this paper this science is applied to PVC extrusion, trouble shooting, scrap recovery, and property development.
Working party on defects in the molecular structure of polyvinylchloride and their relation to thermal stability: General introduction
Authors: Michel Alain
Published: December 2004

Membership of the Working Party during 1977–83 is principally as follows: Chairman/secretary: A. Michel (France).

Members: M.W. Allsopp (U.K.), V. Bellenger (France), J. Büssing (FRG), D. Braun (FGR), A.A. Caraculacu (Romania), E.A. Collins (USA), V. Dobrescu (Romania), K.F. Elgert (FRG), Z. Grubisic‐Gallot (France), A. Guyot (France), P. Kappler (France), T. Kelen (Hungary), M. Kolinsky (Czechoslovakia), C.J.M. Van den Heuvel (Netherlands), W.F. Maddams (U.K.), J.L. Millan (Spain), G. Palma (Italy), R. Panaras (France), G.S. Park (U.K.), Quang Tho Pham (France), U. Schwenk (FRG), P. Simak (FRG), E. Sörvik (Sweden), J.A.J.M. Vincent (Netherlands), D.E. Witenhafer (USA).
Working party on defects in the molecular structure of polyvinylchloride and their relation to thermal stability: General conclusions
Authors: Guyot Alain
Published: December 2004

With the purpose to correlate the thermal stability of PVC with its structural defects, a number of studies have been carried out on 13 PVC samples and in some cases on their fractions. These studies are dealt with structural determination on the one hand and thermal degradation tests on the other hand.
Suspension stabilizers for PVC production III: Control of resin porosity
Authors: Nilsson Holger , Silvegren Christer , Törnell Bertil , Lundqvist Jörgen , Pettersson Sven
Published: December 2004

Suspension PVC resins were prepared using dispersant systems based on a cellulose derivative, Methocel F50, and two poly(vinyl alcohol)s; Gohsenol GH20 and Rhodoviol 5/270. Ammonium laurate and Span 20 were tested as secondary dispersants. The resins were characterized by mercury porosimetry. The results showed that the porosity of the resins increased in the series Gohsenol < Methocel < Rhodoviol. This order seems to follow the order of increasing surface activity. A closer analysis of the data clearly showed, however, that porosity control in S‐PVC manufacture is not due to a pure interfacial tension mechanism, not even in those cases where the dispersant systems do not contain any monomer‐soluble components. Other possible mechanisms by which suspension stabilizers may affect resin porosity are briefly commented upon.
Recovery of reusable poly(vinyl chloride) from plastics waste
Authors: Papaspyrides C. D. , Diakoulaki D. C.
Published: December 2004

Solvent recycling of poly(vinyl chloride) (PVC), on the basis of the cyclohexanone/n‐hexane system, is further studied. By also using water during the washing stage, hexane quantities employed and solvents separation costs involved are drastically reduced. The modification proposed does not result in any alteration of the main characteristics of the process which further can be extended to rigid PVC pipes. No degradation effects were detected while the polymer recycled exhibits mechanical properties comparable with those of the virgin grade PVC especially with waste material of low additives content. Nevertheless, even from pipes, the polymer recovered proved quite suitable for similar applications.
Improving the processing properties of chlorinated PVC resins
Authors: Neuman R. C. , Swanson M.
Published: December 2004

An earlier paper (1) established the need for new compounding technology to deal with changes in melt flow resulting from the postchlorination of PVC resins. The present work attacks the more‐than‐doubled melt viscosity of chlorinated PVC as measured in stabilized resin. The potential for marked reduction in viscosity. improvement in processing stability, and retention of marketable product properties is explored. The development process including the definition of performance requirements, test methods used, and resulting balance of properties is described.
The function of lubricants in processing of rigid poly(vinyl chloride)
Authors: Bower J. David
Published: December 2004

In this review of lubricants and how they function the lubrication mechanism is broken down into three stages: the heat absorption (onset of gelation), gelation (fusion process), and melt flow (postfusion) stages. The terms “internal” and “external” are used to describe the functionality of the lubricant at each stage. It is pointed out that these terms should not be used to label lubricants themselves, because most lubricants perform differently at each stage of processing. How the chemical and physical properties of various types of lubricants perform in each of the fusion stages is also discussed.
The rheology of PVC
Authors: Driscoll Stephen Burke , Grolman Cory Peter
Published: December 2004

A brief historical review has been made of rheological instrumentation developed for measuring the flow properties of vinyl materials. During this maturation of techniques the need for more complete flow characterizations spawned the development of dynamic mechanical instruments. These instruments provided convenient and accurate means of generating complex viscosity (n*) data composed of elastic (G′) and (G″) elements. Examples have been presented illustrating how these newer techniques are able to reliably provide critical data needed to control productivity and product performance properties. Extension of these techniques to on‐line rheometry has improved quality control link in the compounding operation.
An evaluation of the cavity transfer mixer for the extrusion of rigid PVC on both single and twin screw extruders
Authors: Gale G. M.
Published: December 2004

PVC powder compound fed into single‐ and twin‐screw extruders retrofitted with cavity transfer mixers improved PVC grain fusion. Consequent improvements in appearance and properties ought to reduce current tight comprises that must be made between materials costs, output rate, and quality.
Melt flow behavior of blends from poly(vinyl chloride) and epoxidized natural rubber
Authors: Varughese K. T. , De P. P. , Nando G. B. , De S. K.
Published: December 2004

Blends from poly(vinyl chloride) (PVC) and epoxidized natural rubber (ENR) were prepared in a Brabender plasticorder by the melt blending technique. The melt flow behavior of these blends with respect to blend ratio and temperature has been examined using a melt flow indexer and capillary rheometer. ENR decreases the Brabender torque, increases the melt flow index (MFI), and decreases the melt viscosity of PVC in the blends. Arrhenius plots were used to study the effect of temperature on melt flow index (MFI) and viscosity. Moreover, the flow behavior index (n′) obtained from capillary rheometer data was found to be dependent on temperature and blend ratio.
Paint primer system utilizing polyvinyl fluoride film
Authors: Bowley Michael W.
Published: December 2004

A new generation of polyvinyl fluoride film has been specifically developed for use as a primer surface for automotive components which cannot otherwise be decorated with regular OEM paints, or where improved adhesion between the paint and the part is desired. Special film surface modifications provide for excellent adhesion between the film and a broad range of OEM and refinish paints. Lab and proving ground testing demonstrate solid performance throughout the exposure cycles required by FBMS 1–38. Current applications include vinyl and aluminum parts. The polyvinyl fluoride film is applied by lamination to extruded plastic or to coil stock using acrylic and acrylic/epoxy adhesives with proven outdoor durability. For parts subject to aggressive gravel attack, or where bonding to plastic parts is desired simply by heat fusion, a laminate of polyvinyl fluoride with a thin plastic face sheet can be used. Paints are applied according to normal operating procedures. This includes baking temperatures up to 300°F subject to the dimensional stability of the part. The chemical resistance of polyvinyl fluoride allows the use of virtually any chemical or solvent without attack to the film.
The nonyl phthalate ester and its use in flexible PVC
Authors: Wadey Brian L. , Thil Lucien , Khuddus Mo A. , Reich Hans , Ag Basf
Published: December 2004

Six di‐nonyl phthalates varying in degree of branching are evaluated in both suspension and low soap plastisol resin formulations. Comparative plasticizer performance properties of these systems are studied in terms of plasticizer structural differences and their affects on processing parameters and physical properties of suspension resin and low soap dispersion resin formulations.
DSC analysis of fusion level of rigid PVC revisited: Filler effects on thermal analysis data
Authors: Choi P. , Lynch M. , Rudin A. , Teh J. W. , Batiste J.
Published: December 2004

A DSC method for assessing degree of fusion of rigid PVC compounds has been improved, so as to make the technique more precise and objective. Analysis of conventional pipe samples provides assessments of gelation level that accord with solvent resistance and practical experience. However, thermal analysis techniques prove to be unreliable for compounds that contain no filler or more than about 13% filler. At least about 1% filler appears to be necessary for the phenomena that are the basis of this technique. Filler may affect crystallization of PVC compounds.
Bioluminescence resonance energy transfer identify scaffold protein CNK1 interactions in intact cells
Authors: Lopez-Ilasaca Marco A. , Bernabe-Ortiz Julio C. , Na Soon-Young , Dzau Victor J. , Xavier Ramnik J.
Published: December 2004

Connector enhancer of KSR (CNK) proteins have been proposed to act as scaffolds in the Ras‐MAPK pathway. In this work, using in vivo bioluminescence resonance energy transfer (BRET) assays and in vitro co‐immunoprecipitation, we show that hCNK1 interacts with the active form of Rho A (G14V) proteins. The domain of hCNK1 that allows binding to Rho proteins involves the C‐terminal PH domain. Overexpression of hCNK1 does not affect the actin cytoskeleton and does not modify the appearance of stress fibers in cells overexpressing a constitutively active form of RhoA. In contrast, hCNK1 was able to significantly decrease the RhoA‐induced transcriptional activity of the serum response element (SRE) without effect on the Ras‐induced SRE activation. These results identify hCNK1 as a specific partner of Rho proteins both in vitro and in vivo and suggest a role of hCNK1 in the signal transduction of Rho proteins.
STABILITY OF DEAD ZONE BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS INVOLVING TIME DELAYS
Authors: RAO V. SREE HARI , RAO P. RAJA SEKHARA
Published: December 2004

A mathematical model describing the dynamical interactions of bidirectional associative memory networks involving transmission delays is considered. The influence of a dead zone or a zone of noactivation on the global stability is investigated and various easily verifiable sets of sufficient conditions are established. The asymptotic nature of solutions when the given system of equations does not possess an equilibrium pattern is discussed.
DISTINGUISHING SPURIOUS AND NOMINAL ATTRACTORS APPLYING UNLEARNING TO AN ASYMMETRIC NEURAL NETWORK
Authors: HORAS JORGE A. , BEA EDGAR A.
Published: December 2004

We study a neural network with asymmetric connections used as an associative memory. Asymmetry allows the nominal patterns to be stored in cycles. We apply an unlearning procedure, which modifies the synaptic connections. We analyze the global performance, including the network capacity, the attraction basin's size and also the relaxation time distribution. The latter shows a convenient bimodality that is used for discriminating between spurious and stored memory attractors. We show that unlearning in asymmetric networks allows enhancing the global performance of retrieval including retrieval of a sequence of correlated patterns.
EMBEDDING DIAGRAMS OF THE N=2 SUPERCONFORMAL ALGEBRA UNDER SPECTRAL FLOW
Authors: KLEMM HANNO
Published: December 2004

The embedding diagrams of representations of the N=2 superconformal algebra with central charge c=3 are given. Some non-unitary representations possess subsingular vectors that are systematically described. The structure of the embedding diagrams is largely defined by the spectral flow symmetry. As an additional consistency check the action of the spectral flow on the characters is calculated.
A TWO-PARAMETER MODEL OF ELASTIC WAVE VELOCITIES IN ROCKS AND NUMERICAL AVO MODELING
Authors: SUN YUE-FENG
Published: December 2004

Acoustic wave propagation is sensitive to many rock properties including fluid content, porosity, and pore structure, among others. Pore structure is one of the important parameters in controlling both seismic wave velocity and permeability in sandstones and carbonate rocks. For a given porosity of two similar rocks with different pore structure, their acoustic wave speeds can differ 2 km/s and permeability can span nearly six orders of magnitude from 0.01 mD to 20 D in both sandstones and limestones. In this paper, we introduce a two-parameter velocity model defined by porosity and a new pore structure parameter called as frame flexibility factor. Using this model, we define three pore structure types (PST) to quantify the pore structure effects on elastic properties of sedimentary rocks. These three PSTs have their distinct characteristics on synthetic shot gathers and common midpoint gathers. This study indicates that it may be feasible to use this new concept and method to detect pore structure variations in reservoir rocks from field seismic data. This study also helps explain why analysis of amplitude variation with offset (AVO) in some cases fails for fluid detection: pore structure effect on seismic waves can mask all the fluid effects, especially in carbonate rocks.
GROWTH OF 4-(4-DIMETHYLAMINOSTYRYL)-1-METHYLPYRIDINIUM TOSYLATE (DAST) MIXED SINGLE CRYSTAL BY BRIDGMAN–STOCKBARGER METHOD
Authors: USHASREE P. M. , MIDORIKAWA T. , KOMATSU K. , KAINO T.
Published: December 2004

4-(4-dimethylaminostyryl)-1-methylpyridinium tosylate (DAST) is a very promising organic nonlinear optical (NLO) material for future optoelectronic and nonlinear optical applications, though it cannot be grown from molten state. Hence, a derivative of DAST was synthesized and mixed with DAST. The melting point of the mixed crystal decreased drastically, making it possible to grow a single crystal from molten state. In the present investigation, a mixed single crystal of DAST has been grown from molten state by vertical Bridgman–Stockbarger method.
ELECTRO-OPTIC POLYIMIDE WITH HYPER-BRANCHED CHROMOPHORE STRUCTURES
Authors: DO JUNG YUN , PARK SEUNG KOO , PARK SUNTAK , JU JUNG JIN , KIM MIN-SU , LEE MYUNG-HYUN
Published: December 2004

Hyper-branched chromophores were developed and attached to a polyimide backbone. The chromophore structures led to increasing chromophore concentration in polymers. Electro-optic coefficients were measured to investigate the effect of various chromophore concentrations in side chain polymers. Thermal and electric stabilities of poled polymer films were correlated with the hyper-branched structures.
ENHANCING CONVERSION EFFICIENCY IN THE SECOND-ORDER NONLINEAR OPTICAL PHENOMENA
Authors: KIM JONGBAE , JU JUNG JIN , KIM MIN-SU
Published: December 2004

The distributions of electric field and the induced second-order nonlinearity are discussed in a poling scheme where the width of a periodic electrode is shorter than the conventional coherent length. The theoretical aspects of quasi-phase matching for a subsequent experiment in second harmonic generation are analyzed. The present analysis consistently explains that the conversion efficiency can be enhanced if the electrode width is shortened, and maximized if the electrode width is optimized.
SYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF ERBIUM-INCLUDED MESOPOROUS MATERIALS FOR OPTICAL AMPLIFICATION
Authors: CHA YUN HUI , HONG KYONG-SOO , LEE SOON CHANG , JOO DUCK-LAE , LEE JIN KOOK , YU JONG-SUNG , YOON SUK BON , KIM HWAN KYU
Published: December 2004

We have synthesized erbium-included mesoporous materials to enhance optical amplification gain in Er 3+-doped silica materials. Various mesoporous materials such as MCM-41, MCM-48 or SBA-15 were prepared and then erbium ions were filled into the empty pores in the mesoporous materials via sol-gel process through the external modification of the mesoporous materials. All erbium-included mesoporous materials exhibit the near infrared emission band around 1530 nm, corresponding to the characteristic 4 I 13/2→4 I 15/2 transition of erbium ions. The characteristic emission intensity of erbium ions increases with the concentration of Er 3+ ions in the erbium-included mesoporous materials.
PLASTIC PHOTONIC CRYSTAL FIBERS DRAWN FROM STACKED CAPILLARIES
Authors: SHIN BU-GON , PARK JOENG-HO , KIM JANG-JOO
Published: December 2004

Solid and hollow core polymer photonic crystal fibers (PPCFs) were fabricated by drawing preforms of stacked capillaries made of polystyrene (PS). The PPCFs consist of a solid PS core or a hollow core surrounded by periodic air holes of a hexagonal symmetry running along the length of fiber. We have demonstrated the single mode propagation of light through the solid core PPCF at wavelengths of 1.33 and 1.55 μm.
UV-TRIMMING OF TWO-DIMENSIONAL PHOTONIC CRYSTAL STRUCTURES
Authors: SCHMIDT M. , BOETTGER G. , LIGUDA C. , EICH M. , MORGENROTH W. , HUEBNER U. , MEYER H. G.
Published: December 2004

We present a new concept to adjust the transmission properties of a two-dimensional photonic crystal by photobleaching the structure. A square lattice of 500 nm lattice constant and 300 nm hole diameter was fabricated by etching air holes into a slab waveguide consisting of a polymethylmethacrylate polymer covalently functionalized with 10 mol% of the nonlinear Disperse Red 1 chromophore. While illuminating the photonic crystal with UV light the azo molecule bonds degenerate, resulting in a considerable refractive index change and a reduced slab waveguide core layer thickness. Wavelength and polarization dependent measurements show a very large shift of the dielectric band edge of 35 nm in TE and of 27 nm in TM polarization. With our novel concept it is possible to compensate fabrication inaccuracies and to trim photonic crystal transmission properties.