bluuebunny/crossref_metadata_2025_split huggingface dataset:
An examination of the use of principal component analysis and target factor analysis for the determination of Auger depth profiles in two magnetic multilayer metal systems—Cu/Co and Co/Pt
Authors: Wenham M. J. G. , Barkshire I. R. , Prutton M. , Roberts R. H. , Wilkinson D. K. 
Published: May 2005

AbstractTarget factor analysis and principal component analysis have been applied to Auger spectra acquired from two metallic multilayer systems (Cu/Co and Co/Pt) depth profiled using ion beam bevelling. Both multilayers contained alternating 10 nm films, the Co/Pt being capped with 25 nm of Co. The results reveal the expected improvement in the precision of the depth profiles because of the amount of information included in the factor analysis. However, the data sets always contain more factors than expected from the number of different elements present. These extra factors are revealed by examination of the principal components as being due to the depth dependence of the inelastic scattering at energies lower than the Auger features. This yields more information about the samples than can be obtained from inspection of the raw spectra but compromises the accuracy of quantification of the depth profiles.
Reaction mechanism of poly(vinyl chloride) degradation. Molecular orbital calculations
Authors: Bacaloglu Radu , Fisch Michael H. 
Published: May 2005

AbstractSemiempirical Molecular Orbital Calculations (MNDO AM1) support kinetic results concerning the molecular mechanism of thermal degradation of PVC and show that under special conditions radical and ionic mechanisms are also possible. The degradation of poly(vinyl chloride) is a complex chain dehydrochlorination that consists of an initiation process to generate an active intermediate followed by chain reactions that generate additional active intermediates with progressively increased numbers of double bonds. Each intermediate partitions between an intermediate with one more double bond and a stable conjugated polyene with the same number of double bonds. At low and moderate temperatures thermal degradation of PVC in an inert atmosphere is a succession of molecular concerted reactions. The initiation process is a 1,2‐elimination through a four center transition state requiring a synperiplanar conformation. There are two main chain reactions: the first is a 1,4‐elimination from allylic chlorine atoms and methylenes cis to a double bond through a transition state of six centers; the second is a 1,3‐rearrangement of hydrogen atoms catalyzed by hydrogen chloride. The chain reaction is interrupted when a relatively stable trans double bond is formed and no hydrogen chloride is present to catalyze trans‐cis isomerization or 1,3‐rearrangement. Macro carbocations formed by heterolysis of carbon‐halogen bonds in the presence of strong Lewis acids react much faster than does the original PVC in concerted elimination by 1,2‐syn or 1,4‐cis mechanisms, promoting a so‐called catastrophic, very fast degradation. Macro radicals formed by thermal homolysis, irradiation or reaction with promoters can also promote very fast hydrogen chloride elimination because of a special mechanism consisting of a 1,2‐rearrangement of a chlorine atom followed by a concerted 1,3‐elimination through a five center transition state.
Rheology of thermoplastic matrix short glass fiber composites
Authors: Barbosa Silvia E. , Kenny José M. 
Published: May 2005

AbstractAn experimental investigation of the processing of glass‐fiber reinforced polypropylene is presented. Final fiber length distribution, chopped strand disgregation, matrix and composite rheological properties, die swelling, and surface morphology are analyzed. Strand disgregation is observed to increase with shear rate and fiber concentration and to decrease with the length of the die. Final fiber length distribution appears to be independent of die length but decreases with fiber concentration and shear rate. The viscosity and first normal coefficient functions show a linear dependence with shear rate and increases with fiber concentration. The extruded filament surface shows a minor roughness when the shear rate increases. The results of this experimental characterization give useful information for determining the influence of processing variables on the final properties of short fiber reinforced polypropylene and constitutes the first part of a more ambitious project that also includes the development of a modeling strategy of the processing behavior of short fiber composites.
Effects of agitation during VCM suspension polymerization
Authors: Johnson Gary R. 
Published: May 2005

AbstractExperimental work is presented showing the effect of reactor agitation on final resin properties during vinyl chloride suspension polymerization. Experiments were carried out in a large pilot plant facility using a stirred batch reactor of over 5 cubic meters equipped with a turbine impeller and internal baffles. The effects of important agitation parameters such as impeller diameter, width, and speed are correlated with resin particle size distribution using the Weber number. The relationship of resin internal morphology with agitation is also presented using resin plasticizer absorption time and bulk density.
Poly (vinyl chloride) processing morphology
Authors: Rabinovitch Elvira B. , Summers James W. 
Published: May 2005

AbstractThis paper describes how morphology of PVC changes in the Brabender mixing head. At the range of temperatures used for PVC processing, the Brabender torque‐time curve shows minimum torque and maximum torque. The minimum torque is associated with a breakdown of 150 μm PVC grains and 10 μm agglomerates resulting in the release of the 1μm primary particles. The torque increases from minimal interaction between primary particles to the point where primary particles agglomerate at maximum torque so that fibriles can be formed when PVC samples are swollen in acetone and sheard. Further heating reduces the viscosity resulting in lower torque even though residual primary particles still exist with much particle to particle interaction. Primary particle structure disappears at about 215° C with complete melting.
New generation, low taste and odor, high clarity, low blush vinyl compounds
Authors: Wypart Roman W. , Summers James W. 
Published: May 2005

AbstractA new compound for vinyl bottle applications has outstanding taste and odor properties, good thermal stability and color, excellent clarity, gloss, and blush resistance, solving many of the traditional problems associated with these applications. It is shown that blush (haze developed on exposure to alcohol/water) cannot be accelerated, but should be measured by aging at the maximum temperature at which the product is likely to be exposed.
The assembly and use of a computerized torque rheometer
Authors: Brown Randy J. 
Published: May 2005

AbstractThe personal computer has started a revolution in the way data is collected and stored by bringing computer capabilities within the economic reach of even the smallest company. Computer data acquisition and manipulation expands the usefulness of the already valuable torque rheometer as a tool for both rheological studies and routine quality control testing. Analysis of more fundamental rheological properties than just the traditional torque vs. time curve is possible without the time consuming manual data manipulation. Data storage and recall of routine or Q.C. testing for accurate comparisons of results is made easier. Torque rheometer uses made easier by the use of a computer are reviewed. Also given are details of how to hook up a personal computer to an existing torque rheometer.
Initiation of fractures in rigid PVC pipes by soft particles
Authors: Johansson Lennart , Törnell Bertil 
Published: May 2005

AbstractRigid PVC pipes prepared from a particle‐free, tin‐stabilized formulation were subjected to constant internal pressure tests (16 MPa, 60°C), originally in order to study the scattering in time‐to‐failure of pipes free from crack‐initiating particles. Although many efforts were made to produce pipes free from all possible foreign particles, most failures were initiated by particles. The particles in this case were soft and rubbery, Particles of this kind have previously never been found in any of the several hundred fracture surfaces in lead‐stabilized PVC pipes containing calcium carbonate studied in this laboratory. The possible origin of the soft particles is discussed. The results suggest that soft particles represent serious flaws. Besides a full‐grown (penetrating) crack, some of the pipes also contained growing, particle‐induced cracks. In these cases the penetrating crack always contained the largest particle. The presence of growing cracks in fractured pipes indicates the crack propagation rate in rigid PVC to be rather low at the test temperature and stress level used. Fracture surface morphology and creep thinning of the pipe wall at the point of fracture most likely were strongly affected by physical aging during the test period.
Spc on incoming colorants
Authors: Deem D. G. 
Published: May 2005

AbstractStatistical Process Control (SPC) is fast becoming a way of life in industry. Shifting the emphasis from control of the product to control of the process that generates the product by statistical techniques can keep the process parameters in the state of stability. This paper deals with just one segment of SPC; capability studies and analysis of incoming colorants. The need for capability studies originates from renewed drive by customers for acceptable quality products at all times. Manufacturing, both company and supplier, must only ship products that fully meet engineering specifications. This requirement can be met by a consistently performing manufacturing process rather than after the fact inspection. Process capability determination on raw materials must proceed any serious attempt by a company that wants to improve its quality performance. By applying SPC techniques to incoming colorants the customer can determine if the vendors process is in control, if the vendor is using lot selection, and what kind of reject rate the vendor is experiencing among other things.
Kinetics of absorption of N‐alkyl phthalate plasticizers into PVC resin particles
Authors: Storey Robson F. , Mauritz Kenneth A. , Bui Loc Vinh 
Published: May 2005

AbstractThe kinetics of plasticizer absorption by suspension polymerized polyvinylchloride (PVC) have been investigated. The volume swelling ratios of individual PVC particles, immersed in excess plasticizer, were recorded over a period of time using an optical microscope equipped with a high speed camera, Absorption of din‐decylphthalate was studied in the range 70 < T < 100°C. The study shows that the uptake of plasticizer proceeds in three steps: (1) a slow initial absorption into glassy PVC, which is a thermally activated rate process, wherein the polymer is being progressively solvated and evolving toward the rubbery state, (2) the considerable faster diffusion of plasticizer into a rubbery, dynamic polymer matrix, and (3) the asymptotic approach to the equilibrium swelling capacity. Temperature dependency of rate of absorption in the slow initial step was fitted to an Arrhenius expression, and an activation energy for plasticizer uptake was calculated.
The effect of small amounts of calcium carbonate on mechanical properties of rigid PVC
Authors: Bystedt Jan , Erlandsson Ann‐Marie , Enequist Bengt , Josefsson Christina 
Published: May 2005

AbstractThe effect of calcium carbonate in levels of 1 to 5 phr has been studied. Two types of calcium carbonate with an average particle size of 1 and 3 microns have been tested and for each formulation a graph has been drawn with drop impact strength as a function of mechanical processing at constant melt temperature. The maximum impact strength has been read from the graph. The results show that the content of calcium carbonate has an obvious effect on impact strength and that the effect of the fine‐grained filler is clearly positive and that the effect of the coarse‐grained filler is slightly negative.Resistance to internal pressure has been studied only at a filler level of 3 phr. Here the fine‐grained calcium carbonate gives a better result than the coarse‐grained one at a moderate level of mechanical processing, while the two filler‐types are equivalent at high levels of mechanical processing.
ATR‐IR spectra of MBS impact modified and unmodified rigid PVC processed in different ways
Authors: Havriliak S. , Shortridge T. J. 
Published: May 2005

AbstractThe surface IR absorption characteristics of MBS impact modified and unmodified PVC specimens prepared in various ways were determined by ATR‐FTIR techniques. These specimens include compression molded plaques and blow molded bottles. In addition and as a reference point, the IR spectrum of a solution cast film of unmodified PVC was obtained in the transmission mode. The IR spectra in the C‐Cl stretching region for unmodified plaques, i.e. 560 to 750 cm−1, were curve fitted to seven Lorenz functions centered at the literature frequencies, except for one band which was changed from 639 to 636.5 cm−1. Two additional bands (699 and 759 cm−1) were assumed to represent the modifier absorption in modified plaques and bottles. Only peak intensities and band widths were allowed to vary in the curve fitting process. Deconvoluted spectra of selected specimens support the number and location of the absorption peaks.Though these surface spectral changes can be represented in terms of surface configurational partitioning that occurred during processing, a more likely explanation is that conformational changes in the PVC polymer chain has occurred on the surface. Quantities representing the configuration of PVC polymer chains such as non‐syndiotacticity (NSS) or the fraction of PVC backbone carbon atoms that are found in the trans conformation (TRANS) were estimated from Lorenz parameters. NSS and TRANS were found to depend on processing conditions as well as the nature of the modifier.These results are discussed in terms of practical impact tests such as n‐Izod and falling bottle drop tests.
Strain‐induced crystallization kinetics of vinylidene chloride/vinyl chloride (VDC/VC) copolymers. Part II. Effect of temperature
Authors: Lund Monty , England Mark 
Published: May 2005

AbstractThe strain‐induced crystallization (SIC) behavior of vinylidene chloride/vinyl chloride (VDC/VC) copolymer is reported as a function of the uniaxial extension ratio and the temperature of the rubbery amorphous specimen. The copolymer studied was an 88/12 wt/wt VDC/VC copolymer with a weight average molecular weight of 100,000 containing liquid additives that function as processing aids. It was found that SIC is initiated at an extension ratio of approximately 3.5, independent of the stress and stretching temperature. The growth rate of the crystalline phase increases sharply with extension ratio above 3.5. The crystalline phase growth rate at a given extension ratio also increases sharply with temperature between 15°C and 35°C. The implications of film temperature control during bubble expansion on the blown film process are discussed.
A theory for the diffusion of large molecules in amorphous polymers above Tg
Authors: Mauritz K. A. , Storey R. F. 
Published: May 2005

AbstractA general theory of diffusion of large molecules in rubbery amorphous polymers is of interest for the scientific understanding and with regard to material design and process optimization. A broadly applicable model would be useful in developing controlled transport of plasticizers and other additives through polymeric substances. A diffusion model is presented which has been developed for large molecular penetrants above the Tg of the amorphous polymer allowing for required increase in redistribution of the free volume of the polymer structure, as well as the penetrant size and shape. Applicability of the model is demonstrated by comparing theoretically developed diffusion curves for DNOP and DNDP in PVC vs. their weight fractions at 82°C and 91°C. These theoretically derived plots are compared with experimental D vs. w1 curves for these systems generated at lower temperature.
An assessment of PVC smoke
Authors: Smith Gregory F. 
Published: May 2005

AbstractThe conventional test method for evaluating the potential of a material to produce smoke in a real fire is the NBS Smoke Density Chamber. However there are major problems with this approach. These include foremost the fact that its results do not correlate with those of real fires. Furthermore, materials that melt and drip are able to achieve a favorable, but misleading, evaluation because a significant fraction of the sample escapes the burning process. Another problem is that the test takes no account of the role the rate or extent of material burning plays in controlling the smoke density in a real fire situation. The physical problems are solved by material smoke production evaluation techniques based on measurements from the Cone Calorimeter rate of heat release apparatus, which has been developed by the National Bureau of Standards. A smoke parameter has been developed, calculated from cone calorimeter measurements, which reflects the smoke hazard of a real fire. The smoke evolution characteristics for a series of rigid thermoplastic materials have been measured using the cone calorimeter and the smoke parameter concept. The results demonstrate that due to its tendency to resist ignition and to burn very slowly, PVC would produce very little smoke in a real fire situation. Of the 15 materials tested, the expected real fire smoke performance characteristics of PVC were superior to those of all other materials except one.
The combustion toxicity controversy
Authors: Lindstrom Richard S. 
Published: May 2005

AbstractAs long as 20 years ago the need was considered to extend codes concerned with flammability and/or flame spread, to include combustion toxicity requirements. Due to the lack of suitable toxicity tests at that time, the added code requirements for combustion toxicity were not enforceable. Vinyl resin manufacturers have been cited as purveyors of hazardous materials which, when burned, generate a noxious toxic hazard due to the fumes they produce in a fire. Overlooked are such factors that commercial vinyl products have inherent low ignition and flame spread rates and only generate potentially toxic gases when quantities of other materials burning around them heat the vinyls to the decomposition point. In 1983 New York State commissioned a study by A. D. Little Inc. to assess the feasability of incorporating combustion toxicity requirements into building material and furnishing codes of New York State. This paper summarizes these findings, including evaluation and analysis of the data generated by the two tests selected as best meeting the seven critical criteria. Due to differnt combustion toxicity rankings provided by the two test methods, controversial and confusing interpretations reign. As a result, the author provides a four step set of recommendations.
PVC: Packaging issues and regulations
Authors: De La Cruz Peter L. 
Published: May 2005

AbstractAs a result of reports that vinyl chloride monomer migrated at detectable levels into alcoholic beverages stored in poly(vinyl chloride) bottles, FDA proposed to ban the use of rigid PVC for distilled spirits in 1973. A review is presented of FDA's revised proposal for the regulation of PVC food packaging issued in 1986 and some recent developments that have further delayed FDA's issuance of a rule that would lead to the use of PVC in liquor bottles. Despite significant technological improvements in the manufacture of rigid PVC, which has led to drastic reduction of residual vinyl chloride monomer (RVCM) to safe levels, FDA action on PVC has remained stalled. It is concluded that final action by FDA may well depend not on scientific principles, but on the Agency's ability to effectively reconcile the correct scientific, health and legal solutions with the political pressure being exerted by environmentalist groups.
DEHP and toxicity
Authors: Murphy Sandra R. , Wadey Brian L. 
Published: May 2005

AbstractDEHP has had widespread use in flexible vinyls, serving as the workhorse plasticizer. Extensive studies have shown that DEHP has a very low order of toxicity. Originally, concern developed over the effect DEHP might have on the environment. In 1980 results of two‐year feeding studies on rats and mice by NCI caused the emphasis to shift to health aspects of DEHP. Although evidence to date shows DEHP has extremely low order of toxicity (acute), is a minimal irritant to skin or eyes, and poses no hazard to the environment, the chemical industry will continue investigations of phthalate plasticizers.
A molecular model for tensile shear banding and the brittle‐ductile transition in poly(vinyl chloride)
Authors: Havriliak Jr. S. , Shortridge T. J. 
Published: May 2005

AbstractRoetling's adaptation of the Ree‐Eyring model to represent tensile shear banding of polymers in terms of two relaxation processes and Mansfield's model to describe alpha and beta relaxation processes in terms of polymer segment mobility are combined with the particulate structure of poly(vinyl chloride) (PVC) to give a more detailed connection between the macroscopic yielding process and the microscopic mobility of polymer segments. Mansfield's model for relaxation processes is cast in terms of intra‐ and inter‐molecular interactions that serve to hinder orientational motions of polymer segments. The viscoelastic beta process in PVC is interpreted in terms of this model to be a hindered rotation of a segment about its main chain axis. About half of the activation energy of the beta process can be estimated from the barriers hindering rotation in simple alkyl halides. According to tensile yield studies it is the beta process that governs the tensile yield behavior of PVC at high loading rates or low temperatures, i.e. the brittle to ductile transition. Viscoelastic measurements were made on milled compression molded powder blends of PVC of differing K‐values (55–69), over a frequency range of 0.1 to 500 Rad/sec. and a temperature range of −140°C to 20°C. The dependence of the complex compliance on frequency and temperature was represented in terms of a five parameter model proposed by Havriliak and Negami to represent the dielectric dispersions of polymers. The five parameters and their dependence on temperature were estimated using the multi‐response statistical techniques developed by Havriliak and Watts. The parameters are interpreted in terms of Mansfield segmental jumping model.
Glutarimide acrylic copolymer: A new route to high heat PVC
Authors: Patterson John R. , Gruber Charles M. 
Published: May 2005

AbstractPVC is the second largest polymer produced and used in the U.S. It is a self‐extinguishing material with excellent chemical resistance and good dimensional stability. It's greatest asset, however, is it's versatility. By specifically formulating PVC with the numerous types of additives available, a balance of properties can be tailored for a wide range of applications. The most serious disadvantage of PVC is it's low heat resistance which limits the service temperature of finished articles to about 70°C. Now an additive is available that can be formulated with PVC to form miscible, transparent blends with increased service temperature. With proper formulating, the higher HDT can be achieved without sacrificing other properties. It is especially important in clear PVC applications where no increase in haze was noted with the addition of the acrylic imide copolymer. Indications are that substantial market opportunities exist for a high heat PVC. Major market segments include clear packaging with it's need for hot‐fill containers, building products where the desire to use darker colors provides the driving force, and in custom injection molding applications where improved heat resistance would allow vinyl to compete more effectively with FR‐styrenics.