bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the Cs concentration on the formation of MCs+ in SIMS analysis
Authors: Marie Y. , Gao Y. , Saldi F. , Migeon H. N.
Published: May 2005

This study, investigates the influence of the Cs concentration on the formation of MCs+ions (SiCs+ and Cs2+) in a Si wafer. The Cs concentration was varied by:

Studying the surface transition period in a Si wafer under Cs+ bombardment.

Profiling a Cs‐implanted Si sample.

Investigating different Cs+ bombarding conditions which generate different Cs concentrations in silicon under a steady‐state regime.

The results support the recombination model for the formation of the MCs+ ions. From this model, a quantitative evaluation of the ionization probability of Cs0 was obtained.
Generalization of the tougaard method for inelastic‐background estimation in electron spectroscopy: Incorporation of a depth‐dependent inelastic mean free path
Authors: Graat Peter C. J. , Somers Marcel A. J. , Böttger Amarante
Published: May 2005

A generalization of the Tougaard method for subtraction of the background of inelastically scattered electrons from an electron‐energy spectrum is presented. Firstly, a depth dependence of the inelastic mean free path is introduced, which enables the analysis of electron‐energy spectra from elements in inhomogeneous samples. The incorporation of the depth dependence of the inelastic mean free path also provides an equation for the calculation of peak intensities of electron‐energy spectra from elements in inhomogeneous samples and the possibility of estimating the effect of elastic scattering of signal electrons. Secondly, it is shown that the Tougaard method allows the direct calculation of the background of inelastically scattered electrons from a known primary excitation spectrum for an arbitrary in‐depth distribution of electron emitters. The validity of these generalizations is demon‐strated for the case of an XPS model spectrum originating from a substrate covered with an overlayer, by comparing the results obtained in the present study with those reported previously.
Surface studies of the enhanced adsorption of sodium ions onto oxidized surfaces in acetone‐containing aqueous solutions
Authors: Wang Tiejun , Sherwood Peter M. A.
Published: May 2005

The adsorption behavior of sodium ions onto oxidized surfaces was studied with x‐ray photoelectron spectroscopy (XPS). We studied the adsorption of sodium ions onto oxidized surfaces by exposing the surfaces to aqueous neutral and acidic solutions of sodium ions with and without the presence of a high concentration of acetone. The oxidized surfaces chosen were carbon‐fiber surfaces electrochemically oxidized in ammonium carbonate solution, and oxidized aluminum and copper surfaces. No adsorption of sodium ions was found when the oxidized surfaces were exposed to aqueous solutions of sodium ions with no acetone present, but substantial adsorption was seen when neutral aqueous solutions of sodium ions were used with a high concentration of acetone present. Adsorbed sodium ions could not be removed by washing in acetone but could be removed by washing in water. When glutaraldehyde was present in the acetone solutions there was evidence for the surface adsorption of glutaraldehyde/acetone condensation products.
Characterization of a surface‐treated Au–Ag–Cu‐based dental metal–ceramic alloy
Authors: Hautaniemi J. A. , Heinonen M. , Juhanoja J.
Published: May 2005

The oxidation of an Au–Ag–Cu‐based dental metal–ceramic alloy was studied by multitechnique analysis. The elemental spatial distribution of the alloy components was measured by energy‐dispersive x‐ray imaging and scanning Auger microscopy and the depth–concentration profiles studied by XPS and Auger depth profiling. The structure of the oxidized layer was analysed by x‐ray diffraction. Special attention was paid to the pretreatment of the oxidized alloy in order to get a suitable oxide structure, which is known to play an essential role in the porcelain/metal interaction. The studied alloy contained several alloying components, such as In, Cu and Zn, to control melting temperature, strength and porcelain adherence. Oxidation of In could be promoted and that of Cu and Zn inhibited. This is of great importance because In2O3 is known to increase porcelain adherence to noble alloys, whereas CuO tends to cause discolouration of porcelain.
XPS sputter depth profiling of the chemical states for SrTiO3/Si interface by O2+ ion beams
Authors: Kim K. J. , Moon D. W. , Nam S. H. , Lee W. J. , Kim H. G.
Published: May 2005

Because the chemical states of the elements in SrTiO3 thin film on Si are reduced by argon ion beam bombardment, it was impossible to sputter depth profile the chemical states of SrTiO3 thin film by argon ion beams. In this paper, it is reported that the undistorted chemical states of Ti and Si at the SrTiO3/Si interface can be determined with oxygen ion beams at the appropriate 70° angle of incidence, with which either metallic Ti is not oxidized or Ti in SrTiO3 is not reduced. Under the sputter depth profiling conditions, the chemical state of Ti at the SrTiO3/Si interface could be successfully characterized and the effects of post‐annealing at high temperature on the chemical state of Ti were studied. A significant number of Ti atoms in the metallic state were observed at the SrTiO3/Si interface without any post‐annealing but all of them were oxidized to the Ti4+ chemical state after 2 h post‐annealing at the temperatures above 600°C under oxygen flow. The dielectric properties of SrTiO3 thin films on Si were well correlated to the oxidation state of Ti and the broadening of the interface SiO2 layer induced by post‐annealing at high temperature.
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

Target 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

Semiempirical 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

An 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

Experimental 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

This 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.
Skinless suspension PVC—a new type
Authors: Bystedt Jan , Lundqvist Jorgen
Published: May 2005

It is shown that the new, skinless suspension PVC type is superior to standard suspension PVC in the following respects: a more narrow particle size distribution, shorter time to gelation which allows for a higher output rate, and a higher optimal impact strength.
New generation, low taste and odor, high clarity, low blush vinyl compounds
Authors: Wypart Roman W. , Summers James W.
Published: May 2005

A 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

The 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

Rigid 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

Statistical 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

The 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

The 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

The 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

The 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

A 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

The 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

As 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

As 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

DEHP 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

Roetling'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

PVC 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.
Refractive index—A key to understanding color differences
Authors: Donald B. , Mathew R.
Published: May 2005

A problem encountered in the instrumental evaluation of color is the use of integrating sphere spectrophotometers to compare materials where the standard color plaque is not constructed from the same material as the sample. This problem is encountered in the automobile industry, where polypropylene master plaques are commonly used as the standards constructed from different materials than the sample being evaluated. The paper demonstrates how these problems result from the impact of a polymer's refractive index on the reflectivity of light from its surface, and the effect of this light on the instrumental evaluations of color. The paper also discusses how the Fresnel equation can be utilized to calculate the amount of light reflected from a polymer's surface and describes a mathematical procedure that can help compensate for these differences when matching and approving colors.
Flexible PVC challenges for the formulator
Authors: Wickson E. J. , Brookman R. S.
Published: May 2005

The ability of PVC to tolerate large amounts of plasticizers, fillers, and other additives is unique among thermoplastics and has made it possible to develop a wide range of properties in flexible PVC. This versatility, coupled with attractive economics, has been responsible for the growth of flexible PVC over the years. Unfortunately, growth has been slow for many years and flexible PVC markets have been encroached on by competitive materials with higher performance and/or styling advantages. Reasons for the vulnerability of flexible PVC are discussed. In some cases, only minor changes are needed to improve performance while in other cases new developments are needed, many of which are available but not exploited.
Ultra‐high molecular weight PVC resins
Authors: Attwood P. C. , Brookman R. S.
Published: May 2005

Ultra‐high molecular weight PVC resins have properties similar to conventional homopolymer resins, except for a few significant differences. Compounds utilizing these polymers display improved toughness qualities and utility in a wider temperature range. These upgraded properties, combined with the usual advantages of PVC such as colorability, processability, and chemical resistance, should permit these PVC compounds to enter markets previously excluded. New potential markets suggested are footwear utilizing the lighter weight advantage of these tougher compounds, automotive under‐the‐hood applications that employ the broader temperature properties, and replacements for elastomers in gasket and compounds used in automotive and appliance applications.
Update on smoke toxicity of vinyl compounds
Authors: Hinderer R. K. , Hirschler M. M.
Published: May 2005

All organic materials burn and give off toxic products. These always include water, carbon dioxide, and the single gas causing the greatest hazard in fires—carbon monoxide (CO). The intrinsic toxicity of the smoke of all combustible materials, including PVC, is very similar in terms of lethality, with very few exceptions. Toxicity of vinyl compounds is due to two major gases: CO and hydrogen chloride (HCI). Since natural combustible materials are not chlorinated, speculation has arisen about the toxicity of HCl and of PVC smoke. Recent studies have shown that it takes similar doses of HCl and CO to kill rats. Furthermore, rats and baboons will tolerate the same levels of HCl. However, mice are much more sensitive than either rats or baboons towards HCl. Baboons are a very good model for humans; therefore, mice will be killed by exposure to much lower HCl levels than those required to kill humans. HCl concentrations in real fires are quite low: HCl decays rapidly by reacting with wall materials such as gypsum, cement, or ceiling tile. It does not, however, react rapidly with plastic or glass walls, which is where toxicity tests are carried out. Therefore PVC smoke is less hazardous in reality than it appears to be from toxicity test results. Since most products have similar intrinsic toxicities, as regards lethality, the real toxicity in a fire is a consequence of the rate of generation of gases. PVC is a difficult polymer to ignite and burns very slowly, so that it will give off less toxic products per unit time than many other common materials and cause lower fire hazard.
Corrosivity of smoke towards metals
Authors: Hirschler M. M. , Smith G. F.
Published: May 2005

Many people believe that smoke is corrosive only if it contains acid gases. This leads to associating corrosive potential of smoke from materials directly with the amount of acid gases emitted from them during combustion. In extreme cases, chemical composition (i.e. halogen content) is used as a substitute measure of corrosiveness and, therefore, of material suitability for certain applications. The reality is, however, that everything is usually heavily corroded in a fire, whatever the combustible materials involved. In the present project sets of 5 flat carbon steel coupons and 2 copper mirrors were exposed to smoke from several materials for 1 h, in a chamber at room temperature and at 100°C, and kept for 28 days at 75% relative humidity. Various surface treatments were also studied.

The combustibles tested were: a PVC wire compound (PVC WR), a low acid PVC wire compound (PVC LH), a halogen free polyethylene wire compound (PE), wool, wood (Douglas fir, DFIR), polystyrene (PS), neoprene (NPR), nylon (NYL), and a blank (no sample). In order to determine corrosivity the resistance of the copper mirrors and the loss of metal from them was measured. All copper mirrors lost their electrical properties: an almost infinite resistance was measured post‐exposure. The amount of copper lost was very similar for all smokes, but, in the 100°C experiments, the smoke corrosivity ranking was:

All steel coupons were corroded too, at least to some extent. The amount of iron lost depended on treatment as well as on the smoke used. In particular, the highest degree of corrosion was found with coupons exposed at very high temperature, where, again, the most corrosive smoke came from nylon. Common wisdom suggests that acid gases result in corrosion of metal. The present work substantiates this fact. However, the acid gas concentration in the atmosphere does not normally correlate with the level of metal corrosion. The results of this work indicate that metal corrosion depends on factors in addition to acid gases: type of metal, temperature, humidity, length of exposure, surface treatment, and geometry. Furthermore all smokes tested are corrosive.
Vinyl in medicine—a special case
Authors: Blais P.
Published: May 2005

Polyvinyl chloride (PVC) has been used in health care products for more than forty years. Presented originally on the basis of convenience for field and trauma medicine in the military context, the new plastic slowly displaced rubber and glass in intravenous fluid administration systems and later enabled low‐cost production of many new medical products. It was a strong factor in the evolution of hospital disposables. Such substances, long accepted as “low toxicity PVC generiecs” or “medical PVCs” are now being challenged by new classes of materials specifically designed for clinical use. The narrow range of properties offered by traditional PVC technology can no longer fulfill all needs. The choice of new plastics is rationalized on the basis of specific physico‐chemical, mechanical, toxicological, aesthetic, or economic consideration. This presentation addresses the limitations of a plastics technology based on empirical multicomponent formulations as opposed to one based on polymer engineering for critical bilogical, laboratory, and medical applications. Material stability in biological environments, the role of additives, the toxicology of leachables, the biocompatibility of generic medical PVCs, as well as the reasons for its success in health care are discussed. Criteria of suitability for plastics in medicine, the commercial prospects for new PVC blends and copolymers for health care, and the role of national regulatory agencies in decisions that affect the choice of materials for health care, food, and beverages are also discussed.
Effect of injection molding conditions on creep rupture and flex fatigue of rigid PVC
Authors: Forsyth T. H. , Butler R. S. , Summers J. W.
Published: May 2005

Rigid PVC is used in applications requiring long term performance and is sometimes produced under non‐optimal conditions, so that an understanding of the processing variables that affect long‐term performance needs to be obtained. In this study, injection molding parameters were varied according to a statistically designed plan to permit construction of predictive equations for creep rupture, flexural fatigue, and environmental stress cracking. The results show that these properties are strong functions of melt temperature, PVC compound formulation, and of the polymer structure formed during molding.
Evaluation of PVC formulations meeting the various cell classifications in ASTM D‐3034
Authors: Kupfer A. D.
Published: May 2005

Most PVC gravity sewer pipe is manufactured according to the specifications in ASTM Standard D‐3034. This pipe must be extruded from a dryblend which meets one of the three cell classifications listed in the standard. Several PVC formulations which meet these cell classifications are evaluated in this paper. Physical properties such as tensile strength, stiffness, and izod and drop dart impact are measured using both laboratory prepared as well as production run samples. Dryblend flowability is studied using the Jenike and Johnson Flow‐Factor‐Tester. The results show dryblend flow properties will significantly vary as the calcium carbonate filler level in each formulation increases. The use of a coated vs. uncoated filler will improve flow properties especially at higher filler loadings. An analysis of dryblend cost vs. resin price shows resin prices will affect what cell classification is the optimum one to use. Also, maximum filler usage may not result in an optimum cost savings if additional additives such as processing aids or impact modifiers are needed.
Coated metals compatible with PVC jackets for bonded sheath cable applications
Authors: Bow K. E. , Pikula D. G. , Grosser B. K. , Leng P. B.
Published: May 2005

Mechanical strength in the cable sheath is particularly valuable for both fiber optical and copper pair cable. By bonding a PVC jacket to a coated metal tape, a mechanically strong sheath construction is obtained. Changes in PVC jacket technologies have created the need for PVC compatible coated metals with greater tolerance for variations in PVC jacketing materials. This need has been met by the development of a variety of coated metals having thermoplastic coatings which adhere to PVC. As a consequence of this development, new cable sheath designs for use in a variety of applications, such as riser cable and direct buried cable destined for local area networks, are possible. These cables may utilize both copper conductors and/or optical fibers for signal transmission. Data will be provided in the paper to show the effects of extrusion process conditions on adhesion for a variety of PVC resins. The properties of a variety of coated metals—aluminum, copper, and steel—will be discussed. Data on environmental tests of adhesion will be presented. Relationships between adhesion, metal characteristics, jacket properties, and mechanical performance of the sheath will be discussed. Cable applications for the PVC compatible metals will be discussed. Data on the performance of the bonded sheath in riser cable and buried local area network cable will be presented. New cable applications where coated metals in the sheath can provide lightweight armoring will also be discussed.
Sintering of PVC
Authors: Crolla G. , Menges G.
Published: May 2005

Although PVC is counted as one of the amorphous plastics it possesses a distinct powder grain structure. This structure is responsible for various effects; for example it is impossible to sinter thick pieces of rigid PVC dryblend possessing satisfactory mechanical properties. For this application, it is necessary to break down this powder structure into smaller parts, called primary particles, by mechanical shearing and covering these particles with processing auxiliaries enabling it to be sintered. PVC can then be melted by the influence of temperature and pressure in the same way as other thermoplastic materials. For this reason, tests were carried out to determine the best material configuration and the necessary data for the compounding and shearing process, and the sinter conditions. A continuously working roll mill was used to break down the structure. The rolls of this equipment are provided with grooves inclined at a certain angle. With this construction it is possible to achieve a high shearing rate at a low mass‐temperature. Furthermore, all additives can be added during the rolling process, so that no additional mixing process is necessary. These gelable pellets, made by the roll mill, can thus be formed in a die into plates of different thicknesses. Samples were pressed by varying compounding and sintering conditions and these were tested for mechanical properties.
Scanning electron micrograph study of the impact‐improved MBS/PVC blends
Authors: Fann D.‐M. , Shih H.‐Y. , Hsiao C.‐M. , Huang S. K.
Published: May 2005

The improvement of the impact strength of the telecommunication equipment using injection moldable PVC/MBS and other modifiers were studied. The addition of MBS to the PVC was found with rapid increases in the impact stregths in Kg‐cm/cm: 5.5 of pure PVC; 80 of 12 phr and the maximum of 131 of 20 phr of MBS. This increasing impact strength phenomena were subjected to close examinations of SEM, DMTA, and strain‐stress diagrams. The DMTA analysis of the retaining of the individual Tg's of MBS and PVC in the MBS/PVC blends, indicates that no miscibility of MBS and PVC has occurred. The DMTA diagrams of 5, 12, 20, and 30 phrs of MBS in PVC were analyzed and the same samples were also subjected to the impact strength measurements and the SEM examinations. SEM photos showed a gradual transition of the linear to the three‐dimensional arrangements had occurred in the PVC/MBS blends. The formation of three‐dimensional arrangement occurred between 10–20 phr of added MBS. The spacial change from linear to the three‐dimensional arrangements observed in SEM photos correlates the rapid increases of the impact strengths of the specimens tested. Injection specimens of the telephone sets made of PVC/MBS blends with 20 phr of MBS in PVC indicate that the impact strength is averaged at 115 Kg‐cm/cm with tensile strength of 330 Kg/sq cm and elongation of 150%. The similar change of the spacial arrangement is also observed in their SEM photos.
Contribution to the development of thermal stabilization system for vinylidene chloride co‐polymers
Authors: Bednarik Ladislav
Published: May 2005

Selected compounds of phosphorus and tin improve the thermal stability of vinylidene chloride co‐polymers. Although offering superior intermediate color stability, incorporation of polyols will result in erratic processing of the PVdC. Combinations rather than individual compounds appear to stabilize PVdC more effectively and an explanation of the stabilization mechanism is attempted for some compounds.
Use of DSC as a quality control tool
Authors: Williams J. B.
Published: May 2005

A differential scanning calorimeter (DSC) has been found to be a very useful quality control tool for a manufacturer of rigid PVC products. It is particularly good at measuring the consistency of lubricants such as paraffin waxes, and ethylene bis‐stearamide. Test results are presented which clearly show the difference between two paraffin waxes, both of which were considered identical from normal wax specifications, but which performed differently in production equipment. Also presented are the statistics used to draft raw material specifications which include DSC measurements.
Studies on the preparation and properties of particle boards made from bagasse and PVC. I: Effects of operating conditions
Authors: Maldas D. , Kokta B. V.
Published: May 2005

Under study were the mechanical properties of particle boards comprised of ground sugarcane bagasse, PVC, and poly{methylene (polyphenyl isocyanate)} [PMPPIC]. The effects of different parameters, e.g. mixing temperature, molding conditions ‐ platen temperature, time and pressure, particle size of bagasse, concentration of PVC and PMPPIC, as well as dilution of PMPPIC, on the mechanical properties of the resulting particle boards were also investigated. In general, the properties of particle boards change with the variation of mixing and molding conditions. A mixing temperature of 175°C and molding conditions [platen temperature, 190°C; time, 10 min; and pressure, 3.8 MPa] were believed to be optimal conditions of compounding particle boards. Both the mechanical properties and the density of particle boards of bagasse with a mesh size of 60, improved up to 20 weight % of PVC and 10 weight % of PMPPIC.
Mixed metal vinyl stabilizer synergism—reactions with model compounds
Authors: Grossman Richard F.
Published: May 2005

An allylic model compound for degrading PVC, cinnamyl chloride, was found to react with metal carboxylates in n‐butyl acetate at 50°C with rates first order in each component. The corresponding metal chlorides and a mixture of rearranged and unrearranged allyl esters were isolated. With cadmium carboxylates, the rate constant is of the order of 300 × 10−5 sec−1; with barium carboxylates, two orders of magnitude slower. In the presence of excess barium carboxylate, the rate of reaction is first order in cadmium and independent of barium concentration; the product is, however, barium chloride. Under such conditions, only unrearranged allyl ester is recovered. These observations are interpreted in terms of a rapid step leading to formation of a carboxylate‐bridged barium/cadmium intermediate. It is proposed that such intermediates displace chloride from allylic carbon by a concerted mechanism, generating chloride‐bridged reaction products that collapse exclusively to barium chloride.