bluuebunny/crossref_metadata_2025 huggingface dataset:
Functionalization of PVC by grafting of plasticizing group in a twin screw extruder
Authors: Cassagnau P. , Bert M. , Michel A.
Published: May 2005

Substitution reactions are an appropriate way to attach chemical functions to polymer chains for improving properties and to diversify the application of polymer materials. The stereoselective substitution of chlorine atoms affords a useful way to plasticize polyvinychloride (PVC) by attaching appropriate plasticizing functions (ester group) such as isooctylthiosalicylate. Thus, the substitution of chlorine atoms of PVC by reactant bearing plasticizing groups was carried out in a continuous mixing apparatus such as a twin screw extruder. This continuous chemical engineering process taking place in the extruder is studied as the function of the residence time distribution (RTD) measured by a UV method. This function combined with the kinetics of the chemical reaction allows to define a new function G as the distribution of the extent of conversion by analogy with the RTD function.
Optimizing the processing of rigid PVC compounds
Authors: Covas J. A.
Published: May 2005

The optimization of the extrusion of a simple rigid PVC compound in both single and twin screw machines is considered. Mass throughput, short term mechanical properties (tensile and impact). degree of mixing, and energy efficiency were selected as important parameters of the process. Using a statistically based experimental design, regression polynomials of the above variables were defined. The corresponding responses were superimposed and adequate processing windows were defined. Generally, processing rigid PVC at high screw speeds, small die resistances, and medium to high temperature profiles led to the most adequate values of the process parameters.
Polymeric plasticizers for higher performance flexible PVC applications
Authors: Svoboda Ronald D.
Published: May 2005

Flexible PVC applications can be categorized as requiring either general or higher performance characteristics. In many application areas, specification requirements are becoming increasingly more severe requiring the use of polymeric polyester plasticizers in compounding. Polymeric plasticizers provide excellent migration, volatility, fluid chemical extraction, and/or weathering resistance in higher performance applications compared with that obtained from monomeric plasticizers alone.
Improved performance properties of PVC food wrap film
Authors: Falter J. A.
Published: May 2005

A new complex ester additive has been developed for polyvinyl chloride (PVC) food wrap film. This material imparts significantly improved fog resistance and exhibits superior anti‐static characteristics compared to conventional systems. A “mushroom sensitivity” test shows that this new anti‐fog agent has no effect on color or consistency of mushrooms. Effects of conventional anti‐fog systems and this new proprietary product in PVC films are compared in: (a) fog tests at room temperature and at 2°C–5°C, (b) static decay measurements, and (c) thermal stability and optical properties.
Specialty low gloss PVC resin vs. traditional low gloss modifiers
Authors: Reichard Robert
Published: May 2005

Specialty low gloss PVC homopolymer resin effectively reduces gloss levels in flexible PVC compounds at replacement levels of 5 to 30 phr while having little effect on processing parameters. Compounds based on specialty low gloss homopolymers maintain their low gloss characteristics over a broad temperature range and during post heating. These compounds also out perform compounds based on other low gloss modifiers such as acrylics and silicas for physical properties.
Effect of plasticizer type on gelation and fusion of PVC plastisol, dialkyl phthalate series
Authors: Nakajima N. , Kwak S‐Y.
Published: May 2005

Different grades of PVC resins and a variety of plasticizers are used to adjust processability and properties of plastisol. The plastisol, which is a dispersion of fine particles of PVC in plasticizer, is coated on a substrate and heated in an oven to gel and fuse. In the gelation stage the resin particles become swollen with plasticizer and then, in the fusion stage the entire system fuses to become one homogeneous phase. The finished products are flexible PVC such as coated fabrics and surgical globes. Different plasticizers, because of the difference in solvent power, affect the process of gelation and fusion, and hence, processability. This paper examines such an effect systematically by employing a homologous series of plasticizers, dialkyl phthalates. The progress of gelation and fusion are followed by the measurements of dynamic moduli and by the observation with a scanning electron microscope. As it may be expected, the shorter the alkyl chain, the higher the solvent power of the plasticizer.
Model simulation of radio frequency heatseal performance of flexible PVC and other materials
Authors: Ling Michael T. K. , Westphal Stanley , Woo Lecon
Published: May 2005

Despite the long history of the application of radio frequency energies for the joining and assembly of polymer films and articles, a comprehensive, quantitative understanding of all the factors has been lacking. In this article, a quantitative first principle type study is described for flexible PVC of various plasticizer contents and ethylene vinyl acetate (EVA) of different VA compositions. High frequency dielectric data of up to 10 MHz were collected over broad temperature ranges. Separate thermal properties of specific heat and thermal conductivity were determined. In addition, rheological functions over required temperatures and shear rates were applied. Comparisons of predicted heatseal behavior with experimental observations are presented.
Damage zone evolution of PVC/MBS blends
Authors: Bensason S. , Tse A. , Hiltner A. , Baer E.
Published: May 2005

The development of the stress‐whitened damage zone in poly(vinyl chloride) and its blends with methyl methacrylate‐butadiene‐styrene (MBS) core/shell rubber was investigated as a function of rubber content and temperature in a triaxial stress state obtained by slow tensile loading of specimens with a semicircular notch. The onset of stress‐whitening was characterized by a critical mean stress and a critical volume strain. Both of these criticality parameters were affected by temperature, where the blends exhibited a weaker temperature dependence in critical volume strain independent of the rubber content.
Prediction of the long‐term outdoor weathering of poly(vinyl chloride)
Authors: Gardette Jean‐Luc , Lemaire Jacques
Published: May 2005

The prediction of the long‐term durability of PVC polymeric material has been a controversial subject for a long time. Attempts to evaluate this durability have indeed largely preceded experiments on the basic mechanisms of PVC degradation, and they have been essentially empirical. The present paper reports on the general rules that have to be followed to avoid basic errors in predicting the performance of PVC compounds from accelerated weathering experiments.
RF welding of PVC and other thermoplastic compounds
Authors: Leighton J. , Brantley T. , Szabo E.
Published: May 2005

Many of the acclaimed advances in medical sciences have been possible because of the improvements in material sciences, particularly plastic. Radio frequency (RF) sealing of plastics has adopted an increasingly important role as a means of manufacturing medical devices. A high intensity radio signal is used to impart increased molecular vibration in two similar or dissimilar polymers. RF sealing is one of the methods for fabrication that allows the designer to seal or connect different types of plastics. This study addresses the effectiveness of this welding method applied to various commercially significant medical grade polymers with emphasis on PVC of varying hardness. The study compares measured weld strength and weld quality (inspected microscopically) at ambient and elevated temperatures. Also, selected samples of polymeric compounds were exposed after RF welding to gamma radiation, a method of medical device sterilization, in order to study the effects on the weld strength and color shift in the weld area. Of prime interest is the determination of optimum welding parameters for various constructions of plastic compounds.
Changes in properties of rigid PVC during weathering
Authors: Rabinovitch Elvira B. , Summers James W. , Northcott William E.
Published: May 2005

Changes in properties of PVC compounds upon weathering are categorized as due to physical aging or due to chemical change. PVC's tensile strength, flexural strength, tensile modulus, and flexural modulus generally rise slightly with weathering. DSC data on weathered samples show an annealing effect identical to physical aging. The impact strength of weathered PVC is substantially lower than expected from physical aging. Molecular weight of PVC on the weathered surface is lowered upon weathering. Thus the loss of impact strength of PVC upon weathering is mainly due to chemical change.
Effects of nozzle length on mold filling simulation accuracy
Authors: Weir Scott
Published: May 2005

A common assumption in mold filling analysis is that the molding machine is capable of providing a fully pressurized uniform temperature melt to the rear orifice of the sprue. Based upon this assumption, the finite element model then only represents the geometry of the mold itself from the sprue rear orifice forward. This assumption, however, is acceptable only when the injection modeling machine nozzie extension is of such a length that the pressure drop in the nozzle is negligible. For large injection molded parts the exclusion of the molding machine nozzle in the design phase of the mold filling analysis may produce overly optimistic results. This study of an actual large (7.9 kg) injection molded thin wall (4 mm) vinyl part will show the effects of nozzle length on the accuracy of mold filling analysis software predictions. Analytical results with and without representation of the molding machine nozzle in the finite element model will be compared to production trial results.
Effect of plasticizer functionality on the performance properties of flexible PVC compounds
Authors: Ingram Jim E. , Hookanson Stephen H.
Published: May 2005

This paper is on the enhancement of physical properties achieved through utilization of linear plasticizers in flexible PVC compounds. This paper also emphasizes the use of statistical methods and designs of experiments. In a series of experimental designs, electrical, oven‐aging, and low temperature performance of commercially available phthalate plasticizers were evaluated. Test data will be given to show the effect of plasticizer functionality on the performance properties of flexible PVC compounds.
Additives for processing rigid PVDC copolymers
Authors: Patterson Michael C. , Dunkelberger David L.
Published: May 2005

Polyvinylidene chloride (PVDC) copolymers are highly crystalline materials used in packaging applications because of their strength and excellent barrier properties. The crystalline moiety (∼40 to 50%) generally melts from 160 to 170°C and the amorphous phase Tg is between 0 and 35°C depending on the comonomer type and level. PVDC is much less thermally stable than PVC and degrades very rapidly in the same temperature range (i.e. above the Tm) required to process the material. Added plasticizers are utilized to reduce processing temperatures but at the expense of barrier properties. There is a need to process PVDC sans plasticizer to achieve maximum possible barrier properties in multilayer composite sheet and films. Additives will be discussed that have been shown (in laboratory tests) to delay the fusion of the amorphous phase of unplasticized PVDC until the material temperature nears the crystalline melting point, thus reducing the overall heat history with a minimal effect on other important properties.
Trimethylpentanediol dibenzoate: New plasticizer for plastisol screen ink
Authors: Arendt William D. , Beitsch Harry O.
Published: May 2005

Trimethylpentane diol (TMPD) dibenzoate use in vinyl as a plasticizer is not well recognized, and little has been published on vinyl performance characteristics. To assess new applications for vinyl, a basic evaluation was conducted. Based on the results of the screen and other considerations an evaluation for utility in plastisol silk screen ink was conducted. The results indicated that the TMPD dibenzoate performed very well in white ink, requiring good fabric dye bleed resistance compared to polymeric and phthalates currently being used for non‐bleed ink. Non‐bleed characteristics are important for colored tee shirt printing. The benzoate is a good solvator and has excellent extraction resistance.
Lubricant systems for rigid PVC applications
Authors: Falter J. A. , Geick K. S.
Published: May 2005

Lubricants are used in extrusion processing of rigid polyvinyl chloride (PVC) compounds to control fusion and reduce shear heating. Without lubricants, conversion to the melt state results in excessive shear heating and degradation of the compound. The present work compares new lubricant systems containing complex esters with conventional systems based on ethylene bisstearamide (EBS) and paraffin. These new systems provide improved compound stability, weatherability, and physical properties. In addition, use of these systems results in lower compound viscosity compared with the conventional lubricant packages. The effects of other characteristics of these systems, such as the degree of esterification on compound properties, are also discussed.
Characterization of PVC/CPE blends by thermally stimulated current
Authors: Gray R. L. , Ibar J. P.
Published: May 2005

In recent years, the use of polymer blends and alloys has become increasingly important in the development of advanced engineering materials. Through the combination of existing polymers, new and improved properties such as impact strength, chemical resistance, and increased temperature use range have been achieved. An important challenge has been to develop new analytical methods capable of properly evaluating these increasingly complex polymer systems. Careful examination of the blend morphology and degree of internal stress between phases is often critical to the success of the development of new blends and alloys. Blends of grafted and crosslinked PVC and CPE were evaluated by Thermally Stimulated Current (TSC). The extent of crosslinking and degree of interpenetration between the two phases were evaluated by examination of the glass transition peaks generated during the TSC experiments. The unique sensitivity of this technique provided excellent insight, which may allow prediction of long term stability and impact strength based on the degree of internal stress that exists at the phase boundaries. This paper explores the application of TSC as a development tool in the study of impact‐modified PVC.
Recycling postconsumer PVC bottles: Technology and market development
Authors: Carroll William F.
Published: May 2005

The drive to recycle individual polymers in a “closed‐loop”—that is, bottles‐to‐bottles—began in the late 1980s. Technology and market streams for high‐volume packaging plastics like HDPE and PET evolved first. Smaller‐volume packaging plastics have followed. This article describes technology development and the state of the market, including general economics for vinyl recycling. Recycling of PVC packaging, to say nothing of recycling of other plastics, continues to evolve and should be viewed as a work‐in‐progress; still, closed‐loop recycling of PVC bottles is a commercial reality.
Aspects of miscibility in poly(vinyl chloride)/epoxidized natural rubber blends. Part I: Mechanical and morphological properties
Authors: Ishiaku U. S. , Nasir M. , Ishak Z. A. Mohd
Published: May 2005

Miscibility in poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends was studied by examining evidence from tensile, impact, and physical properties. The observation of synergism in tensile strength, percent elongation at break, hardness, and relative density has reaffirmed PVC/ENR blends as miscible systems. Studies of impact properties, however, revealed that the blends are microheterogeneous in nature. This could be attributed to the large sizes of polymer molecules involved and the microgel content of ENR‐50. Results from Fourier transform infrared spectroscopy (FTIR) revealed that hydrogen bonding is extensively involved in PVC/ENR systems. This evidence unveiled the exact nature of the specific interactions responsible for miscibility and hence the enhanced mechanical properties of PVC/ENR blends.
L'Application de la Théorie des Orbitales Moléculaires à l'Interprétation des Déplacements Chimiques et à l'Origine des Lignes Satellites à Basse Energie dans les Spectres de Rayons‐X du Silicium
Authors: Urch D. S.
Published: May 2005

Une méthode est donnée pour l'interprétation des spectres‐X des composés par la théorie des orbitales moléculaires; enparticulaire, l'emission Kβ1,3des composés du silicium. On sait, grace de la spectroscopie photo‐électronique, que l'énergie d'ionisation du niveau 1sdu silicium s'augmente avec l'électro‐ negativité de l'autre élément,Xdans la liaison Si‐X. L'énergie d'ionisation des liaisons s̀, pour Si‐X, augmente aussi pourX= Si → O → F. Donc l'énergie de l'émission Kβ reste presque la même avec la variation deX. Mais si on peut changer l'ionicité de la liaison (avec le même ligand) on aurait, augmentation de l'énergie d'ionisation du silicium 1set diminution de l'énergie de la liaison s̀. C'est pourquoi l'énergie de la rayon‐X, Kβ est 1840 e V pour Si(CH3·CO·CH·COCH3)3+HCL2−(coordination du Si, 6) mais seulement ˜ 1835 eV pour les autres compoés avec coordination 4.
X‐ray spectroscopy on the electron microscope
Authors: Russ J. C.
Published: May 2005

The combination of energy dispersive X‐ray analysis with the transmission electron microscope enables the microscopist to rapidly identify features observed in the normal operation of the microscope, at high magnification. The development of equipment and techniques, especially in the art of specimen preparation, will now permit analysis of as little as 10‐18g, on a spatial scale of a few tens of nanometres. The importance of this technique in the biological and materials sciences promises to be as great as the contribution of the electron microscope itself.
Analogies between quantitative X‐ray fluorescence analysis (XRFA) and quantitative X‐ray photoelectron spectrometry (XPS)
Authors: Ebel H. , Ebel Maria F.
Published: May 2005

The analogies between XRFA and XPS are the basis for the development of quantitative XPS methods for solid metallic samples and also for the determination of inelastic scattering coefficients. The results of the theoretical treatment have been verified by experiments.
A simple calculation model with great versatility for interelement effects in steel by X‐ray fluorescence analysis
Authors: Dahl M. , Karlsson A.
Published: May 2005

Demands of more rapid and accurate answers for the steel plant made it necessary to develop a computerized system for calculation and control of the analysis performed on X‐ray fluorescence and optical emission spectrometers. The interelement effects which occur in X‐ray fluorescence analysis are briefly described and the evolution of a model for these corrections is examined. This model includes corrections for absorption and secondary fluorescence as well as overlapping, dead time effects, etc. which are based on simplified theoretical formulae and can be used for a broad field of applications. The parameters in the model have been determined empirically by measuring a wide range of binary alloys. The interelement effects in optical emission analysis are calculated according to a simple emprical formula. The mathematical models have been fitted to a computer (Datasystem Trask P100) which also controls the two separate spectrometers. Examples are given of routine analysis performed by this model on bulk solids of steels and fused glassy borates of sinters, slags and hard metals. Its chief advantage is that the usual requirement for a great number of standards is eliminated.
Isotope‐excited X‐ray fluorescence analysis of binary alloys using energy dispersion
Authors: Laine E. , Tukia L.
Published: May 2005

A radioisotope‐excited X‐ray fluorescence method for the analysis of binary alloys has been presented. In this energy dispersion analysis no standard specimens were needed. The method was applied to copper‐antimony alloys. The results were checked by another energy dispersion method based on X‐ray diffraction. X‐ray photons from the specimen were measured with an Si (Li) detector and a multichannel analyser was used to sort out the energies. The data were recorded on punched paper tape for computer processing.
Theoretical correction procedures for X‐ray fluorescence analysis
Authors: Shiraiwa Toshio , Fujino Nobukatsu
Published: May 2005

Theoretical to formulae for the fluoresent X‐ray intenisty are obtained and calculations made for nickel + iron + chromium binary and tertiary systems. In the calculation, the continous X‐ray of the irradiating source should be taken into account. The theoretical results agree well with the experimental results but have maximum deviations of 1% and it is thought that the error may be due to coexistent elements. The effect of the coexistent elements can be estimated by theoretical calculation and in routine work the effects are usually expressed as linear expansion factors. These factors are generally obtained from a series of experiments but they can be easily obtained by calculation. The errors caused by the linear approximation are also estimated and it is concluded that the approximation is approved in routine analysis of steels when the composition ranges of the steel type are limited by industrial standards.
Quantitative analysis with an energy‐dispersive detector using a pulsed electron probe and active signal filtering
Authors: Statham P. J. , Long J. V. P. , White G. , Kandiah K.
Published: May 2005

The pulsed beam technique has been used to achieved a high data acuumulation rate in an energy‐dispersive analytical system consisting of an electron probe analyser and the Harwell ‘Highspec’ pulse analyser system 3074. The use of fast beam switching ( ∼ 30 ns transient time) and the special timing facilities available in the Harwell equipment reduce the spectrum contamination due to displacement of the probe during switching to a low level and also provide precise measurements of live time, essential for accurate analysis. Analyses performed at spectrum accumulation rate of up to 12 kP.P.S. shows agreement with accepted values to within ± 1% for major constituents. Simple modification of the system permits accumulation rates up to 25 kP.P.S.
A self‐consistent calibration method for industrial X‐ray spectrometric analyses
Authors: Tertian R.
Published: May 2005

A fast, efficient calibration procedure is proposed based on the accurate analysis of multicomponent systems by means of the influence coefficient method. It relies on a series of well designed additions made to a suitable standard composition, the latter also being used as a reference sample. We show that, for an n element composition, using the hypothesis of constant coefficients, (n + 1) preparations – allowing n(n + 1) intensity measurements – are in principle sufficient to calculate the n2 calibration parameters [i.e. n(n − 1) influence coefficients and n referenc relative intensities] which are necessary for a complete analysis. Actual analyses are carried out by measuring the fluorescent intensities using the ratio (i.e. unknown/standard) method, and then calculating the concentrations from the usual relationships through an iterative calculation, preferably executed by a computer program. A detailed description of a typical application is given, which involved the study of fused specimens (borax fusion) of bauxite and resulted in the very accurate analysis of calcined samples, as well as the direct analysis of raw bauxites following an adequate treatment of the ignition loss problem. While the method is immediately applicable to every system studied in either solid or liquid solution, it clearly extends to compact systems over a suitable compositional range, provided that carefully controlled additions can be achieved and that all prepared samples are homogeneous.
The effect of oxidation state on the intensities of Kβ5 and Kβ″ of 3d‐transition elements
Authors: Asada E. , Takiguchi T. , Suzuki Y.
Published: May 2005

Using a commercially available flat crystal spectrometer in a slightly modified form, an investigation was made of the peak intensity ratios (Kβ5/Kβ1) and the relative intensities of Kβ″ to Kβ5 in different oxidation states of 3d‐transition metal atoms existing in forms of oxidic compounds. The peak intensity ratios (Kβ5/Kβ1) for V, Cr, Mn, Fe, Co, Ni and Cu, as well as the peak profiles of Kβ″ and Kβ5 for V, Cr and Mn, were investigated. Results suggest that changes in the intensities of the Kβ5 and Kβ″ bands can be applied to determining the oxidation number of a metal atom in its oxide.
On trace element analysis of geological samples by X‐ray fluorescence
Authors: Stern W. B.
Published: May 2005

Trace element analysis of geological samples by X‐ray fluorescence analysis presents certain difficulties such as possible line interferences, problems of sample preparation and of mathematical corrections for mass absorption and these are discussed. Analytical methods and results concerning nineteen silicate rock and mineral standards are given.
The generation, absorption and anisotropy of thick‐target bremsstrahlung and implications for quantitative energy dispersive analysis
Authors: Statham Peter J.
Published: May 2005

The bremsstrahlung spectrum from a thick specimen bombarded with 20 ke V electrons is studied with emphasis on the shape rather than the absolute intensity in the energy range 1–10 keV. Monte Carlo calculations are described in detail and used to compare the absorption corrections for characteristic and continuous (bremsstrahlung) radiation from a thick specimen and to determine the extent to which anisotropy modifies the intensity distribution of the continuum. The absorption corrections are found to differ by roughly 5% for f(χ) = 0.5 and 10% for f(χ) = 0.2, but it is shown that the ratio of the corrections can be predicted by using the ratio of two Philibert‐type formulae. Anisotropy has little influence on the absorption correction but changes in atomic number or geometry may result in the intensity distribution being altered by typically 5‐10% across the energy range 1–10keV. Numerical integration gives values for the generated brems‐strahlung intensity which are used in constructing an expression to represent the functional form of the background. Although experimental spectra confirm this to be superior to the combination of Kramers' law and a characteristic absorption expression, several sources of error at low energies, including bremsstrahlung from the Be window, are pointed out and improvements suggested. In order to eliminate the principal uncertainty, that of the overall efficiency curve for a Si(Li) detector and pulse‐processor, it is recommended that a stored spectrum be used as a ‘background standard’ for explicit background corrections. Errors are then reduced to the 0.1% absolute concentration level, which is suitable for quantitative analysis.
The analytical description of the white spectrum from a Mo X‐ray tube
Authors: Castellano E. E. , Rivero B. E.
Published: May 2005

Kramers' formula for the white intensity distribution from a diffraction X‐ray tube is modified to obtain a better analytical description of the observed values. The correction is performed through the multiplication of an exponential factor which depends upon a conveniently defined ‘effective depth’ of X‐ray white production. This effective depth is obtained for a Mo target as a function of operating voltage (varying from 8.5‐50 kV) and wavelength (varying from 0.421–2.310 Å).
Accuracy, precision and detection limits of energy‐dispersive electron‐microprobe analyses of silicates
Authors: Dunham A. C. , Wilkinson F. C. F.
Published: May 2005

Thirty analyses of each of nine well‐characterized silicate glasses and minerals have been made, using a Link Systems Model 290‐2KX energy‐dispersive spectrometer, fitted to a Cambridge Geoscan. Statistical analysis of the analytical data shows that the accuracy and precision of energy‐dispersive analyses are comparable to wavelength‐dispersive analyses, provided that more than about 1 wt% of each element of interest is present. The detection limits for different elements vary accrding to the nature of the sample, the element concerned and the counting time. For 100 liveseconds counting times the detection limits are in the range from 0.05–0.26 wt % of elements.
Computer analysis of X‐ray spectra (EDS) from thin biological specimens
Authors: Bauer Richard , Rick Roger
Published: May 2005

The analysis of energy‐dispersive X‐ray spectra in the low energy region is complicated by the fact that the shape of the background curve is distorted by absorption and the characteristic peaks partially overlap. A computer program (FORTRAN) has been developed, which fits to the measured spectrum an artificially generated one, composed of calculated background and peaks. The parameters defining the artificial spectrum are simultaneously adapted. After four to five iterations of that adaptation, good agreement with the measured spectrum is achieved. This procedure takes about 3 min, using a small computer system.
A proposed model for particle‐size effects in the X‐ray fluorescence analysis of heterogeneous powders that includes incidence angle and non‐random packing effects
Authors: Hawthorne Alan R. , Gardner Robin P.
Published: May 2005

An empirical model that includes the effect of incidence and exit angles and non‐random packing effects is proposed for describing the effect of particle size on the measured X‐ray fluorescence (XRF) response from thick heterogeneous samples. An exact model is derived that illustrates these effects for the ideal case of reglarly oriented cubes, and the previous models at high concentrations of a single homogeneous particale the proposed model and the previous models at high concentrations of a single homogeneous particle type where the largest difference between the previous models is observed. It is shown that at specific angles of incidence and exit the proposed model agrees closely with each of the earlier models. Experimental data taken at different incidence angles show that the proposed model provides the best least‐squares fit to the observed data on the basis of the minimum reduced chi‐square value.
An X‐ray fluorescence method for coating thickness measurement
Authors: Jain S. K. , Gupta P. P. , Eapen A. C.
Published: May 2005

An X‐ray fluorescence method for the measurement of film and coating thickness has been described for use in situations where standard foils of the same material are not available for comparison. The method is based on the measurement of combined mass absorption coefficient of the coating element at the excitation and at the fluorescent energies using thin samples of a compound in which the coating element is present and then calculating the coating thickness using the fluorescence equation. The paper describes the theoretical approach and presents the result of the measurement of certain film and coating thicknesses which support the theoretical considerations.
Deconvolution of energy‐dispersive X‐ray peaks using the poisson probability function
Authors: Ingamells C. O. , Fox J. J.
Published: May 2005

A disability of energy‐dispersive X‐ray (EDX) analyzers is the relatively poor resolution of available detectors. Much work has been done in efforts to separate overlapping peaks. It is recognized that the distribution of signals registered in the several channels around a peak is essentially Poisson, but most efforts at deconvolution have been based on Gaussian statistics, probably because of difficulties encountered in the use of the Poisson formula. These difficulties have been overcome, and a simple method for deconvoluting two, three or more overlapping peaks in an EDX spectrum has been developed.
Comparison between experimental and calculated relative escape peak intensities for an intrinsic Ge detector in the energy region 11–25 keV
Authors: Christensen L. H.
Published: May 2005

Experimental measurements of the relative intensity of the escape peak produced in an intrinsic Ge detector agree quite well with the calculated intensities based on a theoretical model. Contrary to the Si(Li) detector Kα as well as Kβ escape peaks are observed. In the energy region 11–25 keV the Ge Kα escape peak intensities vary from 16.3 to 4.7% and the Ge Kβ escape peak from 2.4 to 0.9% of that to the parent line. Therefore, the escape peaks are not negligible in X‐ray fluorescence analysis, and it may be necessary to numerically correct for them or, by a suitable choice of excitation energy, avoid them completely.
The suitability of energy‐dispersive electron‐microprobe analysis for the investigation of stainless steels
Authors: Dunham A. C. , Wilkinson F. C. F.
Published: May 2005

Carefully polished samples of five austenitic stainless steels have been examined by reflected light microscopy and analysed, using a Link Systems model 290 KX energy‐dispersive spectrometer attached to a Cambridge Instrument Company Geoscan microprobe. At least ten different spots within apparently homogeneous areas of each sample were analysed. While the means of these analyses agree well with the published values, three of the samples have an inhomogeneous distribution of their major elements. Precipitates within the samples are mainly MnCr2O4 and MnS, both with much substitution of the Mn by other elements. Other precipitates are rich in P or Nb. While such blocks are probably sufficiently homogeneous for use as bulk standards, great care should be exercised if they are to be used as microprobe standards. A small excess of silicon was found in most analyses. This is believed to be due to fluorescent excitation of silicon in the detector. Analyses of pure metals suggest that a correction of 0.12 wt % silicon should be applied.
Zur quantitativen mikrosondenanalyse von geologischen proben mittels kombiniertem EDS/WDS
Authors: Schwander H. , Gloor F.
Published: May 2005

Es wird eine quantitative Analysenmethode für geologische Proben (Silikate and Karbonate) mittels Röntgenmikrosonde beschrieben. Im Falle von Silikaten sind fur eine Totalanalyse mehr als 10 chemische Elemente simultan zu erfassen (Haupt‐und Nebenelemente). Zwei experimentelle Moglichkeiten sind realisierbar: (a) Automatischer Sequenzbetrieb mittels Kristallspekrometern; (b) Kombination WDS/EDS (wellenlangendispersives und energiedispersives System). Diese beiden Möglichkeiten werden diskutiert. Technische Angaben und apparativer Aufwand werden beschrieben. Es wird dargelegt, auf welche Weise eine hohe analytische Genauigkeit erreicht werden kann.
Energy‐dispersive XRF spectrometry using secondary radiation in a cartesian geometry
Authors: Bisgård K. Maack , Laursen J. , Nielsen B. Schmidt
Published: May 2005

The design of an energy‐dispersive spectrometer equipped with a conventional X‐ray tube and a secondary target is described. The mechanical construction secures a well defined geometry and a high degree of flexibility. The geometry of the irradiation chamber has allowed the polarizing effect of scattering to be investigated. With emphasis on analysis of infinitely thick biological samples a close approximation to the fundamental parameter method for matrix correction has been studied.
Quantitative X‐ray diffraction analysis with qualitative control of calibration samples
Authors: Knudsen Torben
Published: May 2005

Samples containing identical or very similar phases and differing in their contents of these can be used for calibration of a quantitative X‐ray diffraction analysis without knowing their actual mineralogical composition. The method requires that at least one major peak for each phase is well isolated and that the number of calibration samples is equal to or exceeds the number of phases.
Calibration of tube excited energy‐dispersive X‐ray spectrometers with thin film standards and with fundamental constants
Authors: Van Espen P. , Adams F.
Published: May 2005

The calibration of an energy‐dispersive X‐ray spectrometer is calculated from published physical constants, when the geometry factor of secondary target, sample, detector is obtained experimentally and when the detection efficiency of the Si(Li) detector is calculated from such experimentally derived parameters as the thickness of cryostat window, gold surface barrier contact and silicon dead layer. The results are compared with calibrations obtained experimentally from commercial single element thin film standards obtained by vacuum evaporation and multielement standards obtained by incorporating known amounts of the elements into a thin film polymer. The results obtained from fundamental parameters agree with the experimental data to within 5–6%.
Window contamination of energy‐dispersive detectors in electron microprobe analysis
Authors: Smith D. G. W.
Published: May 2005

Oil film contamination of the Be window of a Si detector has been demonstrated using archival information on X‐ray intensities from calibration standards acquired over a two and a half year period. Although cleaning the window with a solvent restores sensitivity for soft radiation, recontamination can be rapid unless a small heating device is placed close to the window. A mathematical correction is suggested which avoids significant analytical errors from the effect of any contamination which may be present. It can be applied automatically by data processing software using information from the calibration standard spectrum.
The calculation of background in wavelength‐dispersive electron microprobe analysis
Authors: Smith D. G. W. , Reed S. J. B.
Published: May 2005

A procedure has been developed for the calculation of background corrections in wavelength‐dispersive electron microprobe analysis which reduces data acquisition times and offers the possibility of greater accuracy and lower detection limits, especially when the number of peaks concerned is large. An empirical ‘normalized background’ in conjunction with a modified version of Kramers' law (as developed for energy‐dispersive analysis) is used to calculate continuum intensity, enabling the background to be estimated for any wavelength from a single measured value. This approach is compatible with modern trends towards automation of data acquisition and processing.
Evaluation of dead‐time corrections in EDS systems
Authors: Bloomfield D. J. , Love G. , Scott V. D.
Published: May 2005

Two common methods of applying dead‐time corrections in EDS systems, both of which are carried out internally in the electronics, are examined. The Barnhart method shows serious discrepancies when making dead‐time corrections and in certain cases no correction is made at all. The problem is associated with the reliance on the fast amplifier to count all x‐rays collected by the detector. In practice, however, the fast amplifier does not always succeed in carrying out this function since x‐rays with energies < 1500 eV may fall below its threshold level. The problems become worse when a formvar window is substituted for beryllium since a greater proportion of low energy x‐rays can now reach the detector. The magnitude of the discrepancy is shown also to be a function of specimen and electron accelerating voltage. Similar experiments with an EDS system using the Covell method show that no such discrepancies arise.
Real time chemical analysis of phosphoric acid using energy dispersive x‐ray fluorescence
Authors: Marvin Dean C. , Ives Neil A.
Published: May 2005

Energy dispersive x‐ray fluorescence is shown to be an effective analytical method for determination of calcium, sulfur and phosphorous concentrations in wet process phosphoric acid. Periodic monitoring of these quantities is essential to plant operation, and is presently carried out using separate wet chemical analyses. The XRF method described here has the advantages of increased speed, of multi‐element determinations from a single measurement, and of having the potential for on‐line use in an automatic plant control loop.
Automated matrix‐correction of line ratios in energy‐dispersive x‐ray fluorescence spectrum deconvolution
Authors: Van Dyck P. , Van Grieken R.
Published: May 2005

Most computer XRF‐spectrum deconvolution routines make use of fixed intensity ratios for the lines from one element. The magnitude of the error that fixed ratios imply has been quantitatively evaluated for samples with a varible thickness or matrix. A procedure for routinely adapting the line ratios according to the matrix effect in every sample (by making use of the matrix information present in the scatter peaks) enhances the accuracy of the spectrum evaluation.
Quantitative light element analysis using an energy dispersive detector. 1–Dead time and the low‐energy spectrum
Authors: Bloomfield D. J. , Love G. , Scott V. D.
Published: May 2005

A study of the low‐energy region (below 1. 5 keV) of energy dispersive x‐ray spectra has been carried out. Firstly, because some counting systems do not provide a reliable dead time correction, a new method of dealing with the problem is given. Next, the effects of different positioning of the energy discriminator within the analyser circuitry are discussed with reference to the consequences for light element analysis. Electronic noise counts can present a problem for analysis of x‐rays of less than 300 eV and a straightforward method for noise removal is described. Finally, an unexpected artifact in the spectrum below 500 eV is identified; its size is related to the total number of counts in the spectrum and a practical method of dealing with it is demonstrated. Once the above factors have been taken into account a low energy spectrum is produced, consisting solely of characteristic x‐ray lines and a true continuum background.
X‐ray fluorescence analysis of iron ore concentrates
Authors: Turmel S. , Samson C.
Published: May 2005

An x‐ray method has been developed for the routine determination of many elements in iron ore concentrates. The combination of a glass disk technique, the α‐coefficient method of correction and solution of linear equations yields a rapid and accurate method. The determination of eight elements was performed on different certified iron ore concentrates.
X‐ray mapping using a new coded irradiation technique
Authors: Gurker N.
Published: May 2005

X‐ray imaging for physical analysis (elemental mapping) using ‘point’‐scanning methods suffers from long scanning times and low signal‐to‐noise ratios owing to the absence of proper focusing elements. A possible solution to this problem is to increase the interaction area (volume) for a single data acquisition step (‘line’ and ‘area’ scanning) and the use of suitable data to image transformation methods. Since in the past line scanning has been used (image reconstruction from projections), a new scanning concept (mask scanning, ‘coded irradiation’) is now introduced, which is related to coded aperture techniques. The principles, computer simulations and first experimental results are presented.
The problem of irradiation and detection angles in quantitative XRF analysis
Authors: Avaldi L. , Bui C. , Milazzo M.
Published: May 2005

The problem of the dependence of the XRF yield on the irradiation and detection angles and on the sample volume has been critically reviewed. A simple procedure, which accounts for the effect of the sample finite thickness, is given. Applications to the analysis of metal alloys and of organic matrix standards are also reported.
Determination of barium, lanthanum, cerium and neodymium in lateritic materials by various energy‐dispersive X‐ray fluorescence techniques and neutron activation analysis
Authors: Labrecque J. J. , Beusen J. M. , van Grieken R. E.
Published: May 2005

A comparison of four methods for the determination of barium, lanthanum, cerium and neodymium in lateritic materials from Brazil is presented. Three of the methods were based on x‐ray fluorescence (XRF) spectroscopy: two by radioisotope excitation (Co‐57 and Am‐241) and one by secondary target XRF (a molybdenum target with a tungsten anode). The other method was based on neutron activation analysis employing both a Ge(Li) coaxial detector and a high‐purity germanium detector.

The results from these four methods were similar for lanthanum, cerium and neodymium, but for barium at low concentrations (<500 ppm) the neutron activation and the secondary target XRF methods were not suitable. Data on the precision and accuracy of these methods using a series of standard reference rocks are given. The advantages and limitations of each of these methods with respect to the analysis of lateritic materials are discussed.
X‐ray K‐absorption edge of Co and Cu in their 2‐thiopyrrole‐1,2‐dicarboximide‐ and N‐carbamoylpyrrole‐2‐thiocarboxamide‐based complexes
Authors: Rajput O. P. , Nigam A. N. , Padalia B. D.
Published: May 2005

The complexes of Co and Cu with 2‐thiopyrrole‐1,2‐dicarboximide and N‐carbamoylpyrrole‐2‐thiocarboxyamide were studied by recording the x‐ray K‐absorption edge and the extended structure. The nature of the metal to ligand chemical bond has been interpreted in terms of the effective nuclear charge.
Critical comparison of sample preparation methods for major and trace element determinations using X‐ray fluorescence
Authors: Bower Nathan W. , Valentine Greg
Published: May 2005

Ten geochemical reference rocks were used to evaluate the preparation of glass disks and pressed powder samples and counting errors in XRF analyses. Disks prepared with and without heavy element doping at various dilutions with lithium tetraborate demonstrated that all of the methods were limited by preparation errors and that they would give comparable precisions for the 10 major and 12 trace elements determined. However, simplicity of preparation, precision of analysis and total analysis times favored 10:1 or 3:1 dilutions without doping over the doped or pressed powder methods.
Thin‐film thickness calculation to maximize X‐ray fluorescence intensity in transmission arrangements
Authors: Fernández J. E. , Mainardi R. T.
Published: May 2005

Equations were obtained from physical theory to express the fluorescence intensity emitted by a sample in terms of the geometrical parameters of a source–sample–detector cylindrical symmetry arrangement. These equations allow the calculation of the optimum sizes of samples in XRF. The thickness required to maximize the detected fluorescence intensity, in terms of the value of the remaining physical and geometrical parameters, was determined. A thin sample in transmission geometry was considered, where excitation is produced by an isotropic monoenergetic x‐ray source. The sizes of the detector and source are such that they are considered to be dimensionless compared with the sample. These approximations do not affect the validity of the results.
Determination of sulfur content by x‐ray fluorescence in samples containing a single sulfide phase
Authors: Pasitschniak A.
Published: May 2005

Sulfur analysis by XRF cannot, as yet, be carried out concurrently with analyses of major elements. As a result, several alternative means of analysing for sulfur by XRF have been devised. One such analytical method, suitable for analysing sulfur in rocks containing one sulfide‐bearing phase, is presented here. The accuracy and precision of this method, at the 95% confidence level, are 9.8% and 4.4%, respectively.