bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the physical structure of PVC by infrared techniques: A short review
Authors: Cousin P.
Published: May 2005

Infrared spectroscopy is an important analytical technique for investigating polymeric materials. The physical properties of poly(vinyl chloride) (PVC) depend on its chemical and physical structure. Fourier transform infrared spectroscopy (FTIR) and other infrared techniques are commonly used for studying crystallinity, configurational and conformational changes, and chain orientation in plasticized and non‐plasticized PVC. The C‐Cl stretching region is particularly sensitive to the macromolecular structure and important changes may be detected depending on fundamental parameters.
Poly(Vinyl chloride)/plasticizer‐mixture interactions—mixtures of various plasticizers of industrial importance
Authors: Tomaselli F. , Gupta V. P. , Calderon H. S. , Brown G. R.
Published: May 2005

The Flory‐Huggins interaction parameter, x, has been determined as a function of plasticizer composition, ϕ2, for several ternary mixtures of poly(vinyl chloride) (PVC) and different pairs of plasticizers, selected mainly from the family of aliphatic esters. The method employed was the micro‐determination of the apparent melting temperature of a PVC particle in excess plasticizer. In some systems X changed fairly gradually as a function of ϕ2, while other systems exhibited a pronounced minimum in the X – ϕ2 plots. Attention has been drawn to the similarity of this latter behavior to the well known co‐solvency effect. The existence of such minima is of partical interest in plasticized PVC formulations.
Interpretation of DSC measurements of the degree of fusion of rigid PVC
Authors: Teh J. W. , Cooper A. A. , Rudin A. , Batiste J. L. H.
Published: May 2005

Differential scanning calorimetric (DSC) measurements can be used to infer the degree of fusion of rigid PVC articles. The preferred method involves annealing of the specimen at 260°C for 5 minutes, to erase all crystalline structures, followed by a 2 day storage at room temperature. New crystalline entities that are formed give use to an endotherm in the DSC heating mode. The magnitude of this endotherm divided by the total endotherm observed to 220°C can be used to estimate the degree of fusion of the specimen. Data from various processes and different cross‐sections of extruded pipe are consistent with solvent resistance estimations.
Properties and reactions of metal terephthalates
Authors: Baker P. , Grossman R. F.
Published: May 2005

Divalent metal terephthalates such as the zinc, calcium, barium, and cadmium salts appear, from their properties, to be polymeric. As a result, exceptionally high decomposition temperatures and unusually low solubilities are found. Although not in themselves vinyl heat stabilizers, in concert with typical mixed metal stabilizers, divalent metal terephthalates function as boosters and secondary stabilizers. In such capacity, they are characterized by little or no contribution to lubrication, odor, volatility, or moisture absorption.
Properties of γ‐irradiated compostions based on polyvinyl chloride
Authors: Bataille P. , Degrendele C. , Schreiber H. P.
Published: May 2005

A Co‐60 source was used to irradiate compositions based on PVC, and containing plasticizer additives including DIDP and TOTM, and chlorinated PE (CPE). Polyfunctional acrylic monomers were used as crosslinking agents, and irradiation dosages to about 8Mrad were applied to crosslink the compounds. Analyses included crosslink density estimates from solvent swelling data, and stress/strain evaluations of mechanical responses. It was shown that plasticizers reduce the crosslinking efficiency of irradiation, TOTM being the better inhibitor. The presence of CPE counteracts the trend. Mechanical properties differentiate strongly between the use of difunctional and trifunctional crosslinking agents. The latter produce networks at higher dosages (Eq > 4Mrad) characterized by two apparent yield stresses. This suggests the presence of two (or more) distinct network structures. DSC scans of partially crosslinked samples support the contention. The work indicates the importance of composition‐property relationships in multicomponent vinyl systems.
Product liability—who pays for it?
Authors: Gregory R.
Published: May 2005

A previous overview paper presented at the 1987 SPE ANTEC classified product liability in the plastics industry into three types of tort liability, namely: negligence, breach of warranty, and strict liability. This paper takes the problem one step further and attempts to relate product liability directly to the field of extrusion processing of plastics. Responsible parties are identified, reasons for unjust claims aganist some of these parties are explained, and proposed product information is given which resin and additive suppliers might furnish converters to supplement that normally included by manufactures of extrusion equipment.
Practical interpretation of laboratory die swell behavior of PVC extrudates—through correlating circular with non‐circular die performance
Authors: Van Buskirk P. R.
Published: May 2005

Laboratory die swell measurements are routinely measured on many viscoelastic polymer extrudates to characterize thier ability to maintain a specified shape during extrusion operations. The diameters of downstream extrudates obtainable through selected round dies can then be routinely scanned by optical or laser type devices to compare the degree of swell relative to the die diameter itself. Such measurements, while yielding good relative die swell performance between compounds, frequently do not predict the actual die swell levels observed later when the same compound is extruded through production dies of different cross‐sectional shapes and land lengths. This study discusses an alternate method of correlating die swell between dies of different shapes by using a technique derived from fluid mechanics. This concept, used to characterize fluid velocity through non‐circular channels with that observed through circular pipes and ducts, involves the inclusion of a shape factors known as the “Hydraulic Radius” in fluid flow comparisons. When this technique was applied to die swell measurements for extrudates of both a flexible PVC wire jacket compound and a rigid PVC pipe compound, good agreement in actual die swell measurements through both round dies and dies with non‐circular cross sections was obtained. This approach can lend credibility to laboratory die swell measurements and greatly expand their use in predicting production extrusion performance.
Model systems for the study of poly(vinylidene chloride) degradation
Authors: Howell B. A. , Kelly‐Rowley A. M. , Smith P. B.
Published: May 2005

Poly(vinylidene chloride) and copolymers which contain vinylidene chloride (VDC) as a major component undergo thermal degradative dehydrochlorination. Previous work has demonstrated that random double bonds introduced during polymerization/processing serve as the principal defect sites responsible for initiation of the dehydrochlorination reaction. However, residues from degradation of polymers of relatively high molecular weight tend to be crosslinked and relatively insoluble in most solvents. This prohibits the examination by instrumental techniques of these “products” of the degradation reaction. Low‐molecular‐weight model compounds prepared from appropriate multifunctional ketones or by telomerization of VDC monomer in carbon tetrachloride provide materials which upon degradation afford soluble residues which may be characterized by nmr spectroscopy. Initial results suggest that depolymerization/fragmentation can be a major degradation process for these materials.
Suspension, bulk, and emulsion polymerization of vinyl chloride—mechanism, kinetics, and reactor modelling
Authors: Xie T. Y. , Hamielec A. E. , Wood P. E. , Woods D. R.
Published: May 2005

A review of relevant microscopic processes, both chemical and physical, which occur during suspension, bulk and emulsion polymerization (both before and after pressure drop) is given. The state of the art of kinetic modelling of monomer consumption rate, reactor pressure, molecular weight and short and long chain branching development and polymer chain microstructure is illustrated. The effects of diffusion‐controlled termination and propagation reactions and the significant decrease in initiator efficiency and decomposition rate constant at high monomer conversions on the relative rates of various chemical reactions are discussed. The application of temperature programming and semibatch operation are emphasized. Finally, attempts to model polymer particle morphology are described.
High heat vinyl alloys for injection molding applications
Authors: Einhorn Richard A. , Patterson John R.
Published: May 2005

Excessive distortion, warpage, and sagging resulting from heat generation by electrical components and transporting environments has limited the penetration of PVC into high flow injection molding applications such as business machine, appliance, and electrical housings. High flow PVC formulations lose their rigidity at temperatures typical of these applications because the application temperatures are very close to the glass transition temperature (Tg) of PVC. In addition, thermal stresses built in during processing relax near the Tg of the material. Adding a glutarimide acrylic copolymer increases the Tg of PVC; consequently, raising the temperature at which the PVC/glutarimide copolymer blend loses its rigidity well above required application temperatures. This paper describes the effect of adding a glutarimide copolymer on the heat distortion properties and other physical and rheological properties important to high flow injection molding applications.
Prior sample history vs. plasticizer migration phenomena in flexible poly(vinyl chloride) sheets
Authors: Papaspyrides Constantine D.
Published: May 2005

Compression‐molded sheets of plasticized poly(vinyl chloride) (PVC) were prepared to investigate plasticizer migration phenomena into paraffin oil environment. Interest is focused on prior sample history: Specimens from sheets of different dioctyl phthalate (DOP) contents are maintained in the liquid medium until the plasticizer concentration drops to a predetermined value. Then they are switched into “fresh” paraffin oil, at the same immersion temperature, to compare long‐term migration behavior with that of new sheets of this predetermined plasticizer content, i.e., excluding the prior desorption cycle. The results obtained reveal restriction of the migration activity for the two‐stages specimens.
Chemically crosslinked poly(vinyl chloride)
Authors: Rodriguez‐Fernández O. , Sánchez‐Adame M.
Published: May 2005

The effect of mixing time, temperature, and thermal treatment on mechanical properties of crosslinked PVC is investigated. The tensile properties and gel content of crosslinked and uncrosslinked PVC molded samples are evaluated. The cured samples exhibited higher tensile strength and thermal stability than unmodified PVC.
A new PVC based polymer for medical applications
Authors: Brookman Robert S
Published: May 2005

This paper describes a PVC/polyurethane graft polymer that owing to its low extractables is an excellent candidate for medical applications. The composition of the graft polymer is described in detail and the results of animal toxicology, mutagenicity, and other applicable tests needed to qualify for medical use are included. The graft polymer in two different hardnesses is compared to a standard plasticized PVC and a PVC/Polyurethane polyblend in regard to physical properties, melt viscosity, and resistance to radiation sterilization. The graft polymer was found to have several significant advantages.
The oxidative inducation test applied to medical PVC and other polymers
Authors: Woo Lecon , Ling Michael T. K. , Chan Eddie
Published: May 2005

We have examined the applicability of this simple and effective test to polymer systems widely used in the medical industry. First, it was found that not every polymer examined exhibited a distinct onset of autocatalytic oxidation detectable by DSC. However, for cases where distinct onsets are found, powerful insights can be obtained. These included activation energy of the degradation, thermal oxidative shelf life prediction, and correlation, with product performances. Actual examples are presented to illustrate the utility of the test.
Influence of processing on PVC structure property relationships
Authors: Berard Mark T. , Williams Suzanne M. , Parikh Deepak R. , Bethea Sr. Jim R.
Published: May 2005

The influence of the rheology of extruded PVC on the developed morphology and properties was explored. Extrusion conditions for PVC siding formulations with CPE impact modifiers have been investigated on a lab scale twin screw extruder using a factorial model in the experimental design. The independent variables were the barrel temperatures, the die temperature, the hopper feed rate, and the screw rpms. The dependent variables examined include the torque, melt temperature, output rate, fusion level, morphology, and impact resistance. The correlations of the dependent variables with the independent variables were evaluated with the statistical analysis package SASTM. The correlations among several of the dependent variables were also evaluated.
The effect of combining lubricants on fusion behavior of rigid PVC
Authors: Mondragón M. , Flores A. C.
Published: May 2005

The fusion behavior of three different lubrication systems on rigid PVC formulations can be explained using the lubrication mechanism proposed by Rabinovitch. The effect due to the interaction of the lubricants' hydrocarbon chains opposes the effect due to the interactions of the lubricants' polar groups; the fusion behavior depends, therefore, on the final balance of these effects. Highly polar lubricants tend to increase the effect of the polar group interactions, which leads to a decrease in fusion times and an increase in fusion torques.
Antioxidants and UV stabilizers: A summary of their utilization in PVC
Authors: Cortolano Frank P.
Published: May 2005

With the ever increasing demand for better performing products has come the enhanced use of stabilizers and stabilizer systems in both the production and processing of poly(vinylchloride). Antioxidants and chain terminators are commonly used in teh resin manufacturing to improve the initial color and overall quality of the polymer isolated from production. Hindered phenolics and organophosphites have been found to boost the performance of thermal stabilizers for PVC processing. Additionally, as both rigid and flexible PVC compounds have found greater and more demanding weatherable applications both indoors and outdoors, the utilization of UV stabilizers has grown proportionally. For most outdoor applications the UV stabilizer system is essential for the maintenance of color and mechanical properties of the PVC product. This paper attempts to review and discuss stabilizer usage for specific PVC formulations and applications and answer questions as to how and why they are used.
Impact modifiers for PVC
Authors: Lutz John T.
Published: May 2005

With the exception of most PVC pressure pipe and a few profile applications where high modulus is the major consideration, most rigid and semirigid PVC compounds have impact performance requirements that can be met only through the use of impact modifiers. We present an overview of the mechanisms of impact modification and the effects of impact modifier type and concentration, interaction with other formulation ingredients, and PVC morphology as they are influenced by processing conditions. Typical end use formulations are given to illustrate the selection and use of impact modifiers for various applications.
Degradative transesterification of terephthalate polyesters to obtain DOTP plasticizer for flexible PVC
Authors: Dupont L. A. , Gupta V. P.
Published: May 2005

It has been found that dioctyl terephthalate (DOTP), a plasticizer for polyvinyl chloride (PVC), can be made from scrap terephthalate polyesters such as polyethylene terephthalate (PET) by a method known as degradative transesterification. It is recognized that this plasticizer is as good as plasticizer as commercial DOTP, and that it may potentially replace dioctyl phthalate (DOP). The production of DOTP from scrap PET is shown to be cost effective. The use of this technology may provide a solution to a part of our solid‐waste problem.
Effects of recent trends on the stabilization of flexible PVC recyclable compounds
Authors: Baker Paulette , Grossman R. F.
Published: May 2005

Environmental regulations have now fostered two trends dominating flexible PVC compounding. These consist of the elimination of heavy metals and providing modified compositions that minimize disposal problems. The objectionable metals are lead and cadmium. In the U.S., lead stabilizers have been used predominately in wire and cable and roofing applications. Cadmium‐based stabilizers dominated all other areas of flexible PVC compositions except those applications requiring nontoxic components. The problems and achievements encountered in effecting compliance with the need to replace lead and cadmium usage in PVC compositions are discussed and suggested formulation types are provided.
PVC‐based polymer blends: A review of the methods of study
Authors: Zozaya R. Erro , Buso M. , Pezzin G.
Published: May 2005

Since blending or alloying can provide new PVC‐based materials with tailor‐made properties, it would be interesting to review the general methods of studying this topic. This paper deals with the thermodynamics and miscibility testing methods of PVC‐based blends. Although a large amount of literature has been published dealing with PVC blends, special attention is given here to significant examples of the most common and some unusual methods that lead to understanding the basic scientific features of these systems.
Flame retardants and smoke suppressants for flexible vinyl compounds
Authors: Paul David H.
Published: May 2005

This paper reviews a number of technologies employed to reduce flammability and suppress smoke in flexible vinyl compounds. Advantages and disadvantages of the various systems are discussed, along with postulated mechanisms of action. Typical applications, approximate market prices, and major suppliers are also listed.
Traffic cones from recycled vinyl
Authors: Mikofalvy Bela K. , Boo Hwee‐Khim , Summers James W. , Mittendorf Donald H. , Sell W. Allen
Published: May 2005

Injection molded cones have been successfully produced using a high content of recycled wire and cable fluff. The cone meets all general specifications. Its properties are comparable to a conventional plastisol traffic cone. This work demonstrates the feasibility of using recycled wire and cable fluff in injection molding applications.
Metal formates as potential stabilizers for vinylidene chloride copolymers
Authors: Howell B. A. , Rajaram C. V.
Published: May 2005

Vinylidene chloride copolymers have a number of superior properties, most notably, a high barrier to the transport of oxygen and other small molecules. As a consequence, these materials have assumed a position of prominence in the packaging industry. At processing temperatures these copolymers tend to undergo degradative dehydrochlorination. The dehydrochlorination reaction is a typical chain process with distinct initiation, propagation, and termination phases. It has been demonstrated that initiation of degradation is strongly facilitated by the presence of unsaturation along the backbone. Such unsaturation may be introduced via interaction of the polymer with a variety of agents which might commonly be encountered during polymerization or processing. The presence of an unsaturated unit within the polymer generates an allylic dichloromethylene, which may function as a major defect (labile) site for the initiation of degradation. The conversion of these dichloromethylene units into nonreactive groups would interrupt propagation of the dehydrochlorination reaction and lead to the stabilization of the copolymer. Potential stabilization in the presence of metal formates has been examined using a vinylidene chloride/methyl acrylate (5 mol%) copolymer and thermogravimetric techniques. The effect of the metal formate on the stability of the polymer reflects the relative halogenophilicity of the metal cation present. Metal formates of low cation acidity [sodium, calcium, nickel(II) and to a lesser extent lead(II), cadmium, manganese(II) and magnesium] may be expected to be ineffective as stabilizers for vinylidene chloride copolymers. At the other extreme, metal formates that contain cations sufficiently acidic to actively strip chlorine from the polymer backbone, e.g., zinc formate, will function to enhance the degradation process. An effective carboxylate stabilizer must contain a metal cation sufficiently acidic to interact with allylic chlorine and to facilitate its displacement by the carboxylate anion. Copper(II) formate may possess the balance of cation acidity and carboxylate acitvity to function as an effective stabilizer for vinylidene chloride copolymers.
The weathering of vinyl siding
Authors: Stoloff A.
Published: May 2005

This paper describes the development of numerical color hold guidelines proposed as a replacement for the visual weathering standard in the ASTM specification for vinyl siding. Data are presented that indicate that maximum weather color change occurs after 2 to 3 years with very little change thereafter. After approximately 2 to 3 years, the averaged Δ L (lightness increase) for each color was greater at 90° south exposure than at 45° south exposure and Δ L changes were lowest in Arizona, with Florida next, and highest in New Jersey and Ohio. A mechanism is proposed with supporting data that gives an explanation for the observed weathering results.
Plasticization of PVC with ethylene copolymer resins
Authors: Hofmann G. H. , Statz R. J. , Case R. B.
Published: May 2005

Ethylene copolymer resin (ECR) modifiers, designed to be soluble in all proportions in PVC, form a wide variety of plasticized PVC blends. These solid, high molecular weight (Mw > 250,000) resin modifiers, unlike conventional liquid plasticizer, exhibit outstanding permanence in PVC. Compounding procedures, used for liquid plasticized PVC, are sometimes inadequate to produce homogeneous blends of PVC/ECR. A number of effective melt compounding techniques and a new family of ECR modifiers have been developed to produce homogeneous blends exhibiting many outstanding properties, including fluids/chemical resistance, high/low‐temperature service, and weatherability.
Data analysis for non‐statisticians
Authors: Neuman R. C.
Published: May 2005

Experiments generate data. Data generate results. Results lead to decisions. Decisions solve problems. Right??? Well, not always. Things can go wrong….

At the root of the above sequence is data. If the data are not good, the problem is unlikely to get solved. If the data are good, but not properly interpreted, the problem may persist.

One cause of poor data is a poor experimental design. Once run, the results cannot be improved by the best data analysis techniques. Given good data, interpretation can change the conclusions. Data analysis techniques are available that enable the experimenter to

Correct for process drift during a series of experiments.

Study data for outliers, which can falsely influence results.

Determine distribution of data within and between data sets.

Do regression analysis to establish mathematical relationships.

These techniques lead to statistically correct identification of cause and effect relationships, or show that none are present in the data. Rigorous data analysis produces fewer disappointments and more problem solutions.
Single screw extrusion characteristics of a semirigid PVC
Authors: Burke Dennis M.
Published: May 2005

Poly(vinyl chloride) compounds offer a wide range of properties from elastomeric to rigid. For this reason they are well suited for many extrusion applications. However, many processors shy away from PVC because of its challenging process‐ability: PVC is shear sensitive, susceptible to thermal degradation, and highly elastoviscous. This study, although limited, attempts to remove some of the complexity behind PVC extrusion. A semirigid PVC compound was processed on a small laboratory extruder. A factorial experiment was followed to determine the effects of barrel temperature and screw speed on melt temperature, residence time, output, and head pressure. Understanding these fundamental relationships is intrinsic to successful PVC extrusion.
Real time weathering as a test for evaluating materials
Authors: Scott John L.
Published: May 2005

Perhaps as much as 75% of the material placed on exposure in outdoor test fields or in laboratory accelerated testing devices is on test because of a specification requirement that is a part of the condition of sale. Government standards, automotive manufacturers' specifications, and many architectural guidelines are filled with directives instructing prospective suppliers to expose the candidate material to specific weather durability criteria before they submit their product for consideration or acceptance. Approximately another 15% of the materials on exposure is for product warranty. Results from exposures performed in harsh climatic environments to a known industry standard are used to back up claims of product or material durability. Finally, there is a 10% group using exposure sites and laboratory weathering machines for research and development. An ever‐increasing demand for new and more durable products has made the seemingly simple task of weathering a key part of product development, quality assurance, and warranty. Even with the rapid technological improvements in field exposures, laboratory machines, test methods, and evaluation techniques there is mystery, mistrust, and misunderstanding of the weathering process. This paper discusses the reasons for and choices to be made when considering a program for assessing the ability of materials to resist degradation due to weathering.
Preparation of marked poly(vinyl chloride) by reactive processing for identification by UV devices (recycling)
Authors: Hidalgo M. , López D. , Mijangos C.
Published: May 2005

The grafting of sodium 2‐thionaphtholate (NaTN) and sodium p‐thiocresolate (NaTC) in poly(vinyl chloride) (PVC) has been studied in the melt with the aim of obtaining a marked polymer for easy recognition and separation by UV devices. The influence of reactant concentration. DOP concentration, and temperature was investigated to determine the best conditions to obtain a controlled modification in the polymer. High degrees of grafting, efficiencies > 80%, and no side reactions, such as degradation or crosslinking, have been obtained under polymer processing conditions. The reaction of PVC with both reactants is also stereospecific. The ultraviolet spectrum of p‐thiocresolate grafted PVC shows a maximum absorption in the region < 300 nm, and that of a 2% thionaphtholate grafted PVC in the region of 360 nm, which is far from the UV absorption of a plasticized PVC. While the polymer marked with the first reagent can be used without plasticized polymers, the second can also be used with plasticized PVC, and therefore distinguished from polyolefins. The results reported herein may be useful in the development of polymer recycling, although barriers and interferences can exist.
Vinyl durables recycling
Authors: Krause F. E.
Published: May 2005

The Geon Company and the vinyl industry have been very active in recycling for a number of years. A significant portion of that effort has been focused on the vinyl packaging, and the industry has been instrumental in getting automatic bottle sortation commercialized. This paper will focus more on vinyl durables recycling in wire and cable, computer and business equipment, and automotive. In addition it will address a number of environmental attacks currently leveled at vinyl.
Property enhancement of melt processable rubber by blending with thermoplastic and elastomer
Authors: Myrick R. E.
Published: May 2005

The effect of blending various thermoplastics and elastomers with melt processable rubber was studied using ECHIP experimental design. This study shows that with a minimum of tests, key property effects, interrelationships, synergisms, etc., can be identified. The data is useful in guiding the user to produce blends that will optimize properties within a given cost restraint.
Adaptation of solid state detector in X‐Ray powder diffractometry
Authors: Laine E. , Lähteenmäki I. , Kantola M.
Published: May 2005

Rapidly recorded X‐ray diffraction powder patterns from some metals and from rock salt have been obtained by using the energy sensitive Si (Li) semiconductor detector with the multichannel pulse height analyser. The measured energy resolution of the detector system was about 210 eV for Cu Kα radiation. A good agreement was obtained between observed and calculated positions and relative intensities of the diffraction lines.
The N900 non‐dispersive laboratory analyser
Authors: Gamage C. F.
Published: May 2005

The use of non‐dispersive X‐ray fluorescenceanalysis as a general tool in chemical laboratories has developed rather slowly until recently. Most analysers have used radioactive isotopes as the means of excitation and these have been widely used in portable instruments and in on‐line control applications. For general use wide element coverage is necessary, especially the ability to cover elements of lower atomic numbers. For the determination of these light elements a compact source—sample—detector geometry is essential. Early experiments in developing an on‐line system showed the possibilities of one such compact arrangement and resulted in an instrument specifically designed for use in the chemical laboratory. Solid, liquid and powder samples can be examined for silicon and all heavier elements. Basically, sample excitation is by radioactive sources but the instrument was designed to accept also a miniature X‐ray tube which provides higher sensitivity and precision. The measuring head with radioactive isotope or X‐ray tube can be removed and mounted for remote use either for on‐line applications or in an automatic sample presenter.
Particle size effects in X‐Ray emission analysis: Formulae for continuous size distributions
Authors: Hunter C. B. , Rhodes J. R.
Published: May 2005

New equations have been derived to describe the dependence of characteristic X‐ray intensity on particle size in heterogeneous specimens. The formulae include the effects of continuous size distributions, a problem not covered in earlier theoretical work.
Quantitative results with X‐Ray fluorescence spectrometry using energy dispersive analysis of X‐Rays
Authors: Russ J. C.
Published: May 2005

Energy dispersive analysis of X‐rays is a relatively new but rapidly growing technique for X‐ray fluorescence spectrometry offering simultaneous analyses of many elements with sensitivities to a few p.p.m. The digitally recorded spectra lend themselves to processing to remove background and interfering peaks. The net counts for each element can be converted to concentration using any of a variety of mathematical models for interelement effects. When proper specimen preparation is used, final accuracies of better than 1 per cent can be realised over much of the analytical range.
The Si(Li) X‐Ray energy analysis system: Operating principle and performance
Authors: Gedcke D. A.
Published: May 2005

Major improvement in energy resolution in the last two years have made the Si(Li) X‐ray energy analysis system a significant tool for X‐ray spectroscopy. Its high detection efficiency, coupled with ability to analyse for all element simultaneously, has led to the development of several new techniques for X‐ray analysis. This article reviews the present state of the technology for this instrument with respect to performance characteristics and operating principles. A brief reference to its more important applications is also included.
The analysis of Nickel, Gallium and Germanium in iron meteorites by X‐Ray fluorescence spectrometry
Authors: Thomas W. W. , De Laeter J. R.
Published: May 2005

An X‐ray spectrometric technique is described which enables nickel, gallium and germanium to be analysed in iron meteorites. It is important to know the concentration of these elements with sufficient accuracy in order to chemically classify iron meteorites. The spectrometer was calibrated against a set of ‘standard’ meteorites with well‐established compositions.

To obtain better accuracy, modification to the geometry were made to improve the peak to background ratio and eliminate machine background. This enabled nickel, gallium and germanium to be analysed with accuracies of ±0.05 per cent, ±4 p.p.m. and ±9 p.p.m. respectively for counting periods of 1 min for nickel and 10 min for gallium and germanium at the peak and background positions.
The occurrence of parasitic reflections from LiF (220) analysing crystals
Authors: Post B. , Jenkins R.
Published: May 2005

An explanation is offered for the appearance of parasitic reflections from LiF (220) analysing crystals. The reflections appear to stem from an unrestricted vertical divergence at the primary collimator allowing entry of reflections from planes other than that to which the crystal is cut. Careful orientation of the crystal boule before cutting would seem to offer the most convenient way of avoiding the problem.
Analysis of manganese–zinc ferrite by an X‐ray fluorescence method
Authors: Murata Michihiro
Published: May 2005

An X‐ray fluorescence method for the determination of zinc, manganese and iron oxides in manganese‐zinc ferrite has been developed. The content of zinc oxide is determined by using a calibration curve since a variation in the composition of the matrix only slightly affects the intensity of the Zn Kα line. The interelement effect on the intensities of Fe Kα and Mn Kα lines is ignored by the measurement of the intensity ratio, IFe Kα/IMn Kα. The contents of iron and manganese oxides are determined by the method based on the ratio measurement. The proposed method gives a standard deviation of 0.047, 0.047 and 0.030 for Fe2 O3, MnO and ZnO determinations, respectively.
The denver X‐ray conferences
Authors: Newkirk J. B.
Published: May 2005

The Denver X‐ray Conferences are known to X‐ray analysts all over the world and the August meetings are looked forward to with cosiderable entusiasm by the conference regulars. Even those who have never been fortunate enough to attend one of the meetings are able to follow the presentations by means of the excellent conference books Advances in X‐ray Analysis which appear in the Spring following the meeting. The following contribution has been prepared by Professor Newkirk of the University of Denver, who has been active for a number of years on the local Denver Conference committee. Professor Newkirk gives a short history of the conferences and includes some interesting insights into the technical and doemstic arrangements.
Determination of carbon in sediments by electron beam X‐ray excitation
Authors: Poole A. B.
Published: May 2005

Carbon has been determined in sedimentary rock samples using a series of artificial standards. C Kœ line positions for elemental carbon and carbon combined as carbonate differ by 0.51º θ: using an OHM analysing crystal. A ratio of the intensities at the two line positions allows the proportions of combined and elemental carbon present in a sample to be estimated. This proportion is then used to obtain the correct calibration slope factor for the determination of total carbon in the sample.
Data for graphical resolution of two overlapping X‐ray emission lines. Natural widths of K of the elements Z = 10 to 92
Authors: Pessa V. M.
Published: May 2005

The energy difference between two overlapping X‐ray emission lines with Lorentzian shapes has been calculated as a function of the total line profile for several combinations of intensity ratio and half width ratio of the component lines. Natural line widths of Kα1 and Kα2 for neon to uranium are listed from available literature values.
Application de la Spectrométrie de Fluorescence X á la Mesure de l'Espace de Diffusion du Brome dans le Corps Humain
Authors: Bador R. , Vandroux J. C. , Barbier Y. , Girard C.
Published: May 2005

Le volume de liquide extracellualaire (LEC) chez l'homme estun parameétre important pour la deétection de certins eétats pathologiques. La spectromeétrie de fluorescence X permet de mesurer avec une bonne preécision I'espace de deffusion de I'ion bromure et d'en deédrire la valeur du volume de LEC. La meéthode consiste en un dosage direct du brome stabel (80Br) à faible concentration dans les liquides biologiques, en utilisant la raie Br Kα Une étude paralleéle au moyen d'un radiotraceur (82Br)permet de tester la valcur de la meéthode.
The effect of compton scattering on high energy X‐ray fluorescence
Authors: Carr‐Brion K. G.
Published: May 2005

The effect of Compton scattered γ and X‐rays on fluorescent intensities is examined for heavier elements when using radioisotope excitation. It is shown to have a major effect in aqueous solutions and the implication of this on mathematical correction procedures is briefly discussed.
Concerning interelemental crossed effects in X‐ray fluorescence analysis
Authors: Tertian R.
Published: May 2005

Fluorescence crossed effects are discussed as to their exact significance, and relative importance regarding quantitative analysis. While they do not occur in binary systems, crossed effects appear when a fluorescent element is influenced by two or more interfering elements, more particularly when it is subject to enhancement effects. Dissociating crossed effects from pure binary interactions enabled us to establish an accurate general equation for expressing interelement effects in accordance with fundamental theory, and then the associated corrections in any analytical system. As a rule, practical applications should include some suitable modification of the general formula, with respect to the magnitude of corrections for the particularsystem considered.
A new method for first order line interference correction in X‐ray spectrochemical analysis. Application to the analysis of geological samples
Authors: Brändle J. L. , Cerqueira M. I. , Polonio J. B.
Published: May 2005

A mathematical procedure used for correcting the interference between two nearest first order overlapping lines is described. The intensity of the ‘composite’ peak is assumed to be a linear superposition of the individual components; the shift in angular position of the sample. The proposed method is based on the dependence existing between the different parameters involved, which can be represented by a mathematical relationship of the [Ri]=[kij] [Cj], where Ri is the observed intensity, measured at the theoretical 2θ values for the elements involved, Kji are characteristic constants of the angular position and Cj the concentration of the elements.
Theoretical determination of BA/Ti molar ratios of titanates by X‐ray fluorescene spectrometry
Authors: Murata Michihiro
Published: May 2005

A mathematical approach for determining Ba/Ti molar ratios of barium titanates has been made. A computer program applies the necessary corrections for absorption and secondary fluorescene. The method requires no standards and appears to be sufficiently accurate over large compositional variations. Evaluations of the magnitude of the secondary fluorescence contributions on TiKα intensities are given.
X‐ray spectrometric analysis of chlorine in concrete by borate fusion
Authors: Gould R. W. , Healey J. T.
Published: May 2005

Borate fusion over a propane flame has been successfully applied to the analysis of chlorine concentration in cement. Volitization and weight loss effects have proven to be negligible.
Decomposition of the aluminium Kα1, 2 doublet
Authors: Källne E. , Åberg T.
Published: May 2005

It is shown that a unique resolution of the aluminium Kα1, 2 line into Lorentzian components is impossible unless some physical parameters characterizing the components are specified.
Incidence, detection and monitoring of radiation from X‐ray analytical instrumentation
Authors: Jenkins R. , Haas D. J.
Published: May 2005

The incidence of actual and potential radiation accidents is discussed along with the biological effects which have been observed as a result of known incidents. Recommendations are put forward whereby a given operator can reduce the possibility of accidental exposure. A description of active and passive monitoring devices is also given along with a set of guidelines for their selection and use.
Examination of paint smears on clothing by X‐ray fluorescence spectrometry
Authors: West John C.
Published: May 2005

Direct X‐ray fluorescence analysis of pieces of cloth cut from clothing on which there is a suspected paint smear has been found to be a useful forensic technique for comparing a reference paint sample with the smeared substance. Even though the X‐ray method does not compare all the constituents of the paint, it may often be sufficient to distinguish rapidly between two suspect paint sources, and can therefore be a valuable method in paint transfer cases such as hit and run accidents. A feature of the method is that elements present in the cloth, such as sulphur in wool and titanium in some synthetic fibres, can be used as internal standards.
Note on the accuracy involved in the use of effective mass absorptiobn coefficients in X‐ray fluorescence analysis with polychromatic radiation
Authors: Mencik Zdenek
Published: May 2005

The question as to whether the multiple least squares regression of X‐ray fluorescence analytical data used in an earlier paper and based on an equation derived for excitation by monochromatic radiation can be considered as valid with sufficient accuracy in an experimental system using polychromatic radiation as source of excitation was examined. The results of computer simulation of the process of X‐ray fluorescence show that although definite differences in the intensities of fluorescent radiation arise as a result of the substitution of polychromatic primary radiation for a monochromatic source, the flexibility of the particular equation used for regression eliminates such deviations by incorporating them in the experimental regression coefficients. The overall accuracy of the regression was found to be satisfactory by any practical criteria.
Monte Carlo simulation of the X‐ray fluorescence excited by discrete energy photons in homogeneous samples including tertiary inter‐element effects
Authors: Gardner Robin P. , Hawthorne Alan R.
Published: May 2005

A Monte Carlo model is derived for the simulation X‐ray fluorescence from homogeneous samples including primary, secondary and tertiary fluorescence events. The model is designed specifically for an annular radioisotope source mounted coaxially with a circular detector. It is verified with analytical relationships for the limited case of fixed sample entrance and exit angles. The results indicate accuracies (2% or better) that are well within our knowledge of X‐ray fluorescence parameters (such as fluorescence yields), yet can be calculated with very modest (15 seconds) digital computer calculation time.
A simple empirical inter‐element correction procedure applied to the X‐ray fluorescence analysis of nickel‐base alloys
Authors: Griffiths J. M. , Whitehead H. R.
Published: May 2005

The application of a simple, empirical inter‐element correction procedure to the analysis of nickel‐base alloys is described. The correction factors are considered in relation to the effects predicted from a study of the mass absorption coefficients.
Eine vereinfachte Formulierung des Korngrößeneinflusses
Authors: Weber K.
Published: May 2005

Bei geeigneter Wahl der Koeffizienten ist es Möglich, die bekannte hyperbolische Gleichung für die Röntegenspektral‐analyse des Zweistoffsystems auch im Gebiet des Korngrößen‐einflusses beizubehalten. Damit wird die experimentelle Bestimmung und Handhabung der Korngrößenparameter wesentlich vereinfacht, wie an Hand von Literaturdaten belegt wird; insbesondere ergibt sich ein Weg, den Korngrößeneinfluß von anderen Einflußfaktoren abzutrennen.
A simple method for background and matrix correction of spectral peaks in trace element determination by X‐ray fluorescence spectrometry
Authors: Feather C. E. , Willis J. P.
Published: May 2005

Between adjacent major element absorption edges, background intensities at differing wavelength positions were found to be related linearly. Also, background intensity at any position is linearly related to the reciprocal of the mass absorption coefficient for any wavelength between the absorption edges.

The method presented here allows for the determination of background, as well as mass absorption coefficient, by a single measurement at an interference‐free background position (which can be the Compton scatter ‘peak’). If the mass absorption coefficient is already known, backgrounds may be calculated directly.

Tests on geological materials show that, while not as accurate as conventional methods of background determination, relative accuracies of two to five percent are obtainable with a very considerable saving in time, since intensity at only one background position need be measured. Use of low dispersion high reflectivity analysing crystals, e.g. LiF(200), is possible because it is no longer necessary to attain interference‐free background positions between peaks.

Furthermore, the method is ideally suited to the determination of background intensities in energy dispersive systems where spectral resolution is a problem and in multi‐channel units where only one channel need be used for the determination of both mass absorption coefficient and backgrounds for a group of trace elements.

The method has been used in the low cost determination of trace elements in large numbers of geochemical prospecting samples.
Spectral distributions of X‐rays produced by a general electric EA 75 Cr/W tube at various applied constant voltages
Authors: Loomis T. C. , Keith H. D.
Published: May 2005

Spectral distributions of X‐rays generated by a General Electric EA 75 Cr/W dual target X‐ray tube have been measured using exciting voltages of 20, 30, 40 45 and 50 kV c.p. A carefully characterized and previously described lithium‐drifted silicon detector was used and corrections were applied for second order effects in the detection system and for detector efficiency. Relative errors are believed to be of the order of 1% over most of the range covered (4‐50 ke V), increasing to about 10% over the lower range of photon energies (2.5‐4 ke V). Although the resolution of the detector is limited, it was nevertheless possible by computation to separate groups of characteristic spectral lines from continua and to determine self‐absorption jump ratios in these continua. Spectral distributions obtained using chromium and tungsten targets are compared with earlier data of Birks and his collaborators and with the forms of continua predicted by Kulenkampff's equation. Agreement is only fair. The experimental method employed for studying spectral distributions is believed to be the most accurate and reliable now available and is particularly convenient in terms of the rapidity with which distributions can be measured. Further work is required to remove remaining uncertainties concerning the generation of X‐rays at thick targets.
Evaluation of a practical background calculation method in X‐ray energy analysis
Authors: van Espen P. , Adams F.
Published: May 2005

The background beneath the fluorescence lines of energy dispersive X‐ray spectra obtained with a molybdenam secondary target tube‐excited system can be obtained from the intensities of the coherently and incoherently scattered radiation. The background intensity at a particular energy is equal to the product of a proportionality factor multiplied by the incoherently scattered radiation intensity, plus another proportionality factor multiplied by the coherently scattered radiation intensity. The proportionality factors are determined from measurements of a number of molybdenum‐loaded cellulose filters.

The proposed procedure provides accurate results for the analysis of complex X‐ray spectra of thin samples of varying composition.