bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid‐phase degradation of poly(vinyl chloride)
Authors: Minsker K. S. , Abdullin M. I. , Zaikov G. E. 
Published: May 2005

AbstractThe main kinetic regularities of the thermal and thermal‐oxidative degradation of poly(vinyl chloride) (PVC) in the liquid phase have been analyzed in comparison with the solid‐phase degradation of PVC. The thermal (in an N2 atmosphere) degradation of PVC in the form of dilute solutions is characterized by a number of essential distinctions, the primary peculiarity consisting of a lower dehydrochlorination rate due to the retarded reaction of the formation of magnified image bond polyconjugated systems. The same is observed for the thermal degradation of PVC plasticized with di‐ and polyesters. On the contrary, in an oxygen‐containing atmosphere the solvents promote PVC decomposition. Accelerated PVC degradation under such conditions is due to the solvent oxidation that causes the appearance, within the system, of products activating the PVC macromolecular decomposition. The intensified degradation processes are accounted for, in the first place, by an increased reaction rate of the statistical (by the random law) detachment of HCl from normal macromolecular units. In general, the kinetics of the thermal‐oxidative liquid‐phase degradation of PVC is determined by the partial pressure of oxygen in the reaction zone, by the quantity of the solvent introduced into the polymer, as well as by the oxidative stability of the solvent. It has been shown that an effective stabilization of PVC in the liquid phase, particularly in the systems highly plasticized with esters, can be achieved through stabilizing the solvent, first of all, rather than the polymer, against oxidative decomposition. In this case the PVC dehydrochlorination rate decreases sharply and may reach an essentially lower value than under similar conditions of the solid‐phase thermal degradation of PVC. PVC stabilization with respect to the reaction of HCl elimination achieved through the solvent stabilization against thermal‐oxidative decomposition has been called the effect of “echo‐stabilization” of PVC.
Vinyl chloride, identification and solution of a problem
Authors: Ernst Werner 
Published: May 2005

AbstractMore than 8 years have passed after the identification of vinyl chloride (VC) as having a carcinogenic potential. It appears to be useful to recapitulate the development of the VC disease and of the measures in the PVC producing plants, taken until now, in the Federal Republic of Germany. It can be shown how this problem has been solved by cooperation of all persons involved, the chemical companies, the organizations responsible for occupational safety, the trade‐unions representatives, the physicians and other experts. As a result of the manifold technical, medical, and other precautions, the operating conditions could be improved essentially. Currently, concentration levels of VCM in the workplace amount to 1 ppm or below in nearly all plants.
The effect of amines on the dehydrochlorination of poly(vinyl chloride)
Authors: Bowley H. J. , Gerrard D. L. , Biggin I. S. 
Published: May 2005

AbstractA study has been made of the effect of amines, particularly those used as catalysts in the preparation of polyurethane foams, on the dehydrochlorination of poly(vinyl chloride) (PVC). It has been shown that when PVC is heated at a temperature of 80°C in the presence of amines the levels of dehydrochlorination produced are considerably greater than those found if no amine is present. This has been attributed to a chemical dehydrochlorination reaction and could well have implications with respect to the physical and mechanical properties of the polymer for certain of its commercial applications.
Melt elasticity behavior and extrudate characteristics of rigid poly(vinyl chloride)/epoxidized natural rubber miscible blends
Authors: Varughese K. T. , De P. P. , Sanyal S. K. 
Published: May 2005

AbstractA study on the melt elasticity behavior and extrudate characteristics of melts of rigid poly(vinyl chloride), PVC, and rigid poly(vinyl chloride)/epoxidized natural rubber (ENR) miscible blends were conducted. Extrusion studies were carried out in a capillary rheometer and examinations of the surface characteristics of the extrudate were made by taking photomicrographs in a scanning electron microscope. The anomalous behavior in the die swell ratio of rigid PVC arising from the particle agglomerates continued in its blends up to 50 wt% composition of ENR. Temperature independence for high ENR blends was noted for the principal normal stress difference and elastic shear modulus, when shear stress was held constant. Recoverable shear strain and die swell ratio behaved identically in terms of blend composition and processing temperature. Factors which control the extrudate distortion and melt fracture of the melts of rigid PVC/ENR systems were fusion of particle agglomerates and strength of melts. Diamond cavitations were typical of the extrudate surface of PVC melts as those of the fracture surface of the tensile failure of PVC. Conditions to obtain a smooth extrudate surface of rigid PVC melts in blends with ENR have been found to be the low ENR content, low shear rate, or stress and high processing temperature.
Study of the physical structure of PVC by infrared techniques: A short review
Authors: Cousin P. 
Published: May 2005

AbstractInfrared 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

AbstractThe 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

AbstractDifferential 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

AbstractDivalent 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

AbstractA 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

AbstractA 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

AbstractLaboratory 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

AbstractPoly(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

AbstractA 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

AbstractExcessive 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

AbstractCompression‐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

AbstractThe 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

AbstractThis 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

AbstractWe 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

AbstractThe 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

AbstractThe 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

AbstractWith 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

AbstractWith 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

AbstractIt 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

AbstractEnvironmental 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

AbstractSince 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.
Traffic cones from recycled vinyl
Authors: Mikofalvy Bela K. , Boo Hwee‐Khim , Summers James W. , Mittendorf Donald H. , Sell W. Allen 
Published: May 2005

AbstractInjection 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.