bluuebunny/crossref_metadata_2025 huggingface dataset:
The reactions of stabilizers prior to the appearance of degradation in vinyl
Authors: Grossman Richard F.
Published: April 2004

The infrared spectra of simple allylic chlorides dissolved in a variety of primary stabilizers indicate a shift in the CC stretching frequency to higher energy. This suggests that in the presence of primary stabillizers, allylic unsaturation has less of an activating effect on chlorine. The initial effect of stabillizer addition, therefore, may be simply to increase the activation energy of degradation, and the first function of the vinyl stabilizer, that of a reverse catalyst of the degradative process.
The influence of acrylic impact modifiers on the weld strength of extruded rigid PVC
Authors: Weier Jane E.
Published: April 2004

The weld strength of a PVC window profile is a function of complicated interactions among many contributing variables. Major determinats of weld strength include the PVC formulation, profile processing conditions, and welding parameters. Impact modifiers enhance weld strength due to their well‐known effects on PVC mechanical properties. For modifiers having similar impact efficiency, the contribution to improved weld strength is maximized through optimization of the PVC viscosity and blend morphology at the weld line.
Relation of crystalline structure and mechanical properties of nucleated polypropylene
Authors: Pukánszky Béla , Mudra István , Staniek Peter
Published: April 2004

Four heterogeneous nucleating agents were added to polypropylene (PP) homoblock and random copolymers. Melting and crystallization of the polymers were studied by differential scanning calorimetry (DSC), and characteristics derived from the crystallization exotherms were related to the mechanical properties of injection molded bars. A very close correlation was found between the crystallization characteristics and Young's modulus of the polymers. The general correlation proved to be valid for all three polymers studied and also for each nucleating agent. The developed empirical correlation makes possible the approximate prediction of stiffness from a simple DSC trace. Further study is needed to give the relationship better physical meaning and to extend it to other mechanical properties.
Nucleating agent effects on selected properties of polypropylene
Authors: Wong A. C‐Y , Leung W. W. M.
Published: April 2004

A study of nucleating agent effects on the selected optical and mechanical properties of a semicrystalline homoisotactic polypropylene is presented. The results showed that the type and concentration of the nucleating agents to be added, and the screw speed during the compounding process, were of vital importance. It was also noticed that the improvement in optical clarity due to the addition of the additive might not necessarily benefit the mechanical properties of injection molded articles.
Effects of fiber orientation on strain concentrations in glass reinforced polyamides
Authors: Bernhardt Anne , Panzeri Giovanni
Published: April 2004

Orientation of reinforcement fibers in injection molded parts is a key factor in determining their strength and stiffness: therefore stress‐strain analyses based on isotropic material models produce only rough results. We present a flow/strain analysis methodology that accounts for the actual anisotropic material properties and fiber orientation. Material properties are determined by experiment, fiber orientation is inferred from flow simulation results (velocity vectors). Stress/strain fields are calculated by means of finite element analysis. Results show that for notched parts molded from short glass reinforced polyamide resin, there is a significant dependence of the strain concentration on the local fiber orientation resulting from different injection molding conditions.
Volatiles released during the weathering of PVC
Authors: Carlsson D. J. , Krzymien M. , Worsfold D. J. , Day M.
Published: April 2004

Volatile organic compounds and organochlorine species liberated by UV exposure of poly(vinyl chloride) (PVC) siding samples have been identified and preliminary quantification made. These volatiles included those remaining in a PVC sample after weathering or laboratory UV exposure and which could be released by thermal desorption. In addition, by using a flow‐through cell and granular carbon adsorbents, volatile species directly desorbed during laboratory UV exposure were measured. Total directly desorbed organochlorine compounds were about 1/20 of the weight of hydrogen chloride as measured by conductometric analysis, Quite similar products were observed from old (∼1984) and current (1995) commercial siding formulations. Observed volatile compounds are proposed to come from the TiO2‐controlled photo‐oxidation of both PVC and its additives such as impact modifiers.
Reversible discoloration effects in the photoaging of poly(vinyl chloride)
Authors: Gardette Jean‐Luc , Lemaire Jacques
Published: April 2004

It is often observed that the photochemical degradation of titanium dioxide pigmented PVC leads to a latent discoloration that is revealed only during a further period of storage of the aged material in the dark. This effect is reversible, and photobleaching can be provoked by a new irradiation of the polymer. This behavior can be attributed to the formation of polyenic sequences with a short conjugation length, which present an absorption below 400 nm. The screen effect of the pigment protects these polyenes against photooxidation, which permits these polyenes to accumulate in the degraded polymer. In the absence of light, these polyenes can be thermally isomerized, so leading to isomer forms absorbing at longer wavelength above 400 nm. This absorption is responsible for a yellowing of the polymer. The isomerization is perfectly reversible and a further irradiation provokes the conversion to the isomer form absorbing below 400 nm, leading then to a photobleaching of the sample. These experiments can be repeated many times before any distortion occurs.
Applications of infrared spectroscopy to customer problems in the vinyl industry
Authors: Garcia Dana
Published: April 2004

Identifying polymers, additives and contaminants presents unique challenges. Fourier transform infrared spectroscopy (FT‐IR) coupled with spectral searching techniques is a very efficient and powerful methodology to answer most identification questions. It is based on the unique IR spectrum characteristic of each compound. This paper outlines procedures employed in the identification of typical PVC formulations, starting with the resin and proceeding to impact modifier, process aids, lubricants, stabilizer system and fillers. The emphasis is on FT‐IR microscopy as the most versatile approach requiring small samples and minimal to no sample preparation. Other commonly used FT‐IR techniques are also outlined. Wet separation protocols, applicability and limitations as related to FT‐IR analysis are discussed. Typical examples include vinyl siding, packaging and bottle formulations as well as contaminants often encountered in these formulations and raw materials.
Halogen‐free flame‐retardant plastics for electronic applications
Authors: Von Gentzkow W. , Huber J. , Kapitza H. , Rogler W.
Published: April 2004

In order to meet international standards, printed circuit board (PCB) base materials have to be flame‐retardant according to the UL 94V specification. Up to now this has been achieved with FR4 materials by using brominated aromatic components. FR4 materials are glass epoxy based and are by far most prevalent in PCB production. Unfortunately, in the case of fire or smoldering, these materials evolve highly corrosive, and, under unfavorable conditions, even highly toxic decomposition products. In the search for flame retardancy without the use of bromine, the effect of different structural elements on the burning behavior of cured resins has been investigated. As a result of these investigations an epoxy resin was developed that contains tailor‐made N‐ and P‐containing constituents that form flame‐retardant structures during processing and curing of the material. The new material meets all requirements for printed circuit boards and can be processed without any need to modify established technologies. Analytical and ecotoxicological investigations of the combustion products of the new material show that they are comparable with those of wood from the beech tree. PCBs and electronic assemblies manufactured therefrom successfully passed all functional tests. The base materials recently became commercially available.
Carboxylation of polypropylene by reactive extrusion with functionalized peroxides for use as a compatibilizer in polypropylene/polyamide‐6,6 blends
Authors: Manning Steven C. , Moore Robert B.
Published: April 2004

Variable quantities of functionalized peroxides bearing carboxylic acid groups were reacted with polypropylene (PP) in a twin‐screw extruder. Systematic variations in the molecular structure of the peroxides were found to significantly affect the grafting efficiency of the carboxylic acid group onto the PP backbone, as well as affect the polymer degradation process. This behavior was attributed to the relative reactivities of the different free radicals generated by thermal decomposition of the peroxides. Furthermore, the functionalized polypropylene (f‐PP) was investigated as a compatibilizing additive for 80/20 PP/PA‐6,6 (polyamide 6,6) blends. With incorporation of the f‐PP into the blends, differential scanning calorimetry (DSC) showed an 80°C decrease in the PA‐6,6 crystallization temperature. A near linear increase in the impact strength of the blends was observed with f‐PP incorporations up to 30% of the PP phase. Moreover, blends containing 30% f‐PP demostrated impact properties approaching that of pure PA‐6,6.
The role of silicone powders in reducing the heat release rate and evolution of smoke in flame retardant thermoplastics
Authors: Pape Peter G. , Romenesko David J.
Published: April 2004

New powdered silicone additives for plastics have been developed that give benefits in flame retardant formulations. Cone calorimeter evaluations of thermoplastics, with or without other flame retardant additives, show reduction in rates of heat release, smoke generation, and carbon monoxide evolution. Other benefits that have been observed are: improved processing, reduced torque, reduced build‐up on screws, and increased impact strength. The effect of silicone powder additives on the combustion of several thermoplastics will be shown. A suggested mechanism is discussed.
A practical guide to the identification of monomeric plasticizers in flexible PVC compounds
Authors: Kozlowski Richard R. , Gallagher Thomas K.
Published: April 2004

The performance of a flexible PVC compound is often defined by its plasticizer content and composition. A simple, accurate and fast method of plasticizer identification can therefore be an effective quality control test and benchmark performance in new product development studies. Gas chromatography provides the most effective plasticizer identification method. Gas chromatography can be supplemented by infrared and liquid chromatography and physical observations to confirm identity.
Variations on the oxidative induction testing methodology for polymer analysis
Authors: Woo Lecon , Ling Michael T. K. , Westphal Stanley P. , Ding Samuel Y.
Published: April 2004

We have modified the ASTM method on oxidative induction testing (D‐3895‐92) into a generalized technique with considerably expanded applications to polymer systems in addition to the polyolefins. Testing parameters we have experimented with success are: much wider temperature ranges, oxygen pressure, combination of oven aging and the differential scanning calorimeter, and both the exothermic and endothermic degradation polymer systems. In terms of non‐olefin polymer systems, we have obtained good results from flexible PVC formulations, thermoplastic polyesters, styrene based thermoplastic elastomers, among others. Insights generated from these tests can be used to optimize polymer selection, formulation and processing conditions.
Ultraviolet light resistance of vinyl miniblinds
Authors: Grossman Richard F. , Krausnick Dale
Published: April 2004

Accelerated ultraviolet light aging was carried out using lead stabilized commercial vinyl miniblinds as well as a vinyl composition designed for outdoor use. The levels of surface lead found after such exposure were compared with results obtained in the field by the North Carolina Department of Environment, Health, and Natural Resources (DEHNR).
Acid absorbers as PVC costabilizers
Authors: Grossman Richard F.
Published: April 2004

Phase transfer catalyst coatings have been developed that increase the stabilization effectiveness of acid absorbers such as hydrotalcite and Type A zeolite in combination with lead stabilizers, and also with organotin stabilizers having structures that previously did not provide synergistic effects with acid‐absorbing costabilizers.
Factors influencing the adsorption of stabilizers onto carbon black: Flow microcalorimetry studies
Authors: Peñta J. M. , Allen N. S. , Liauw C. M. , Edge M. , Valange B.
Published: April 2004

The surface activity of various kinds of carbon black toward phenolic antioxidants and hindered amine light stabilizers (HALS) was examined by using flow microcalorimetry (FMC). Phenolic hydroxyl and ester groups were found to be the moieties responsible for the adsorption activity of primary phenolic antioxidants onto the carbon black surfaces. Furthermore, a difference in the degree of phenolic hydroxyl hindrance by alkyl groups was found to be the main factor affecting the adsorption activity of the phenol group. A difference in the degree of substitution of the piperidine amine, as well as the number and type of functionality per molecule, are important factors that were found to influence the adsorption activity of HALS. Data from adsorption studies using model compounds, some of which represented functional portions of the stabilizer molecules, reflected behavior sin ilar to that observed with the stabilizers. In addition, these latter results showed that FMC analysis can yield potentially useful information beyond that given by the usual parameters such as BET surface area, I2, DBP, and CTAB adsorption values. Differences in the behavior between types of carbon black were evident and showed that the specific surface area is not the most important factor in the adsorption/desorption activity, but also the chemical nature of the surface. From the activity observed for model compounds, it was deduced that the presence of secondary and tertiary amine in the backbone and branch structures also has an important role in the adsorption activity of polymeric HALS. In general, the observed quantities can be related to the values of adsorption/desorption energy and to the molar mass of the probe.
Molecular weight distribution of commercial PVC
Authors: Pepperl G.
Published: April 2004

The molecular weight distribution (MWD) of commercial suspension grade poly(vinyl chloride) (PVC) resins with K values from 50 to 93 and mass grade PVC resins with K values from 58 to 68 has been determined by size exclusion chromatography (SEC), using literature Mark‐Houwink coefficients. The MWD is characterized by the number average molecular weight (Mn), the weight average molecular weight (Mw) and the polydispersity (Mw/Mn). Our results for Mw are consistent with recently published data, but we find different results for Mn and consequently for Mw/Mn. The polydispersity of PVC increases with increasing K value. This effect can be explained by two mechanisms. The first mechanism is a reduced terminating reaction rate between two growing polymer chains (disproportionation) at higher molecular weight owing to the reduced mobility of the polymer chains. The second mechanism is long‐chain branching of molecules with high molecular weight which lets the molecules grow at two ends. For two examples graphs of the measured MWD are compared with the theoretically expected MWD.
Guarding against bloom in FR/UV polypropylene fiber
Authors: Kuvshinnikova Olga I. , Lee Robert E. , Favstritsky Nick
Published: April 2004

Displacing polyamide and polyester fibers in the carpet industry with polypropylene (PP) has been hampered in a few key market segments. Markets that require resistance to flame and ultraviolet light have been the most difficult to penetrate owing to both technical and economical reasons. The migration of additives to the surface (blooming) has been one significant technical problem. This paper will review progress in the stabilization of flame‐retarded PP fiber and present new advances in this field.
Synthesis and antioxidative properties of novel multifunctional stabilizers
Authors: Habicher Wolf D. , Pawelke B. , Bauer I. , Yamaguchi K. , Kósa C. , Chmela Š. , Pospíšil J.
Published: April 2004

New multifunctional stabilizers containing hindered amino, phosphite, and in some cases also free phenolic moieties have been synthesized starting from tris(diethylamino)phosphine. Some of them proved to be efficient stabilizers for model hydrocarbons and for polypropylene during processing, thermo‐, and photooxidation. Various sterically hindered phenols, amines (HAS), and phosphites have been modified by the reaction with isophorone diisocyanate (IPDI) to get new multifunctional stabilizers for polymers. The synthesized products have been investigated regarding their thermal and antioxidative behavior. The novel urethane stabilizers are, depending during the polymer processing to release the antioxidatively active parent phenols.
Benefits of a high‐performance phosphite in the gamma irradiation of polyolefins
Authors: Stein Daryl , Stevenson Don
Published: April 2004

The highly active process stabilizer bis(2,4‐dicumylphenyl)pentaerythritol diphosphite (P1) was compared in a series of polyolefin formulations with tris(2,4‐di‐t‐butylphenyl) phosphite (P2). Because of its high activity, there was less polymer degradation during processing with P1 as compared to P2. As a result, improvements in color and other physical properties were observed for the polymers, not only during processing, but also after treatment with gamma radiation.
New class of antioxidants
Authors: Grossman Richard F. , Detweiler Mark B.
Published: April 2004

Antibiotics containing phenolic ‐OH groups, such as amoxicillin and cefadroxil, have been found to be strong antioxidants in common plastics to a much greater extent than would be guessed from their structures. Vancomycin, which contains several such groups, is also a powerful antioxidant. It is possible that this characteristic plays a part in inhibiting bacterial expression of counteragents such as β‐lactamases.
Thermal degradation of PVC in the presence of polystyrene
Authors: Yao Qiang , Wilkie Charles A.
Published: April 2004

The thermal degradation of poly(vinyl chloride) (PVC) and blends of PVC with polystyrene has been studied using thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. The degradation of PVC commences at weak links by an ionic pathway, but there is evidence to suggest the presence of a radical pathway at high temperatures. While there is some chemical interaction between PVC and polystyrene, the principal mode of stabilization is a physical process.
Vinyl chloride in rural water from pre‐1977 applications of PVC pipe
Authors: Carroll William F. , Eckstein Dave
Published: April 2004

In the early 1990s, vinyl chloride monomer (VCM) was found in a rural water system that included poly(vinyl chloride) (PVC) pipe manufactured prior to 1977. Because VCM, considered a human carcinogen, was not regulated in pipe until 1977, some pre‐1977 pipes could contain it at significant levels. Manufacturing processes adopted in 1975 and in place by 1977 reduced VCM levels by as much as a factor of 1000. Pipe manufactured by using the newer resin technology does not show detectable VCM migration under any reasonable installation circumstances. Migration of VCM is a function of pipe size, VCM concentration at time of installation, water temperature, and flow rate. History, scientific investigations, and conclusions drawn from field investigations are summarized. Tools for the determination of possible candidate systems, potential noncompliance, and remediation, both short‐term and long‐term, are provided. A spreadsheet‐based computer model of diffusion is described.
Enhanced weatherability of exterior PVC building products
Authors: Girois Stephane , Schipper Peggy S.
Published: April 2004

Poly(Vinyl) Chloride (PVC) is used extensively as a material for the growing building‐products market. The color preferences of consumers for markets such as vinyl siding have forced the industry to seriously reconsider the use of PVC especially for the medium‐to‐dark color palettes, where the performance is critical. Organotin mercaptides have always been the stabilizers of choice in the U.S. market because of their inherent outstanding heat‐stabilization properties. On the other hand, this technology is also known to be a compromise between processability and weathering characteristics. In a market that drives for excellence, all additives must be optimized to meet the final performance requirement. Organotin carboxylates and specifically maleates have long been known for excellent weathering but have not been used extensively in the industry owing to less‐than‐optimum intrinsic heat stabilization efficiency, and in some cases, troublesome lachrymatory properties. A new generation of organotin maleates has been successfully developed to address both issues. This paper describes the improved lachrymatory behavior of the new technology compared to standard organotin maleates and also shows its outstanding weathering performance in PVC capstock compared with conventional organotin mercaptide during natural aging.
Sustainable development: How to weigh both economical and ecological cost? A new strategy for a combined optimization
Authors: Spindler Ernst‐Josef
Published: April 2004

Sustainable development attempts a combined optimization of ecological, economical and social development. One task, then, is to measure progress in these terms, i.e. to weigh, e.g. economical against ecological advantages. We have developed and tested a method that combines at least the most essential criteria of ecological and economical development, i.e. the ecological cost derived from ecobalance studies and the economical cost derived from life‐cycle cost calculations. The method consists of improving lower‐cost products as long as they are cheaper than their alternatives. These improved products, which cost the same or less, are then compared in an ecobalance study with the alternatives. In many cases these improved products show by far the best ecological results and cost no more than the alternatives. They thus have the highest optimization potential both from an economical and ecological point of view. A strategy that strives towards sustainable development optimizes rare economical and ecological resources in an ecoefficient way. One formulation of such a strategy: Use lower‐cost products and improve them by using all or part of the price difference relative to their alternatives; these optimized products are very often much better when comparing ecobalance results, and not more expensive than their alternatives. This is shown to be the case for PVC windows compared both to wood and aluminum windows. An alternate method, the monetarizing of ecological impacts, is briefly discussed.
New halogen‐free fire retardant for engineering plastic applications
Authors: Levchik Sergei V. , Bright Danielle A. , Alessio Gerald R. , Dashevsky Sophia
Published: April 2004

A comparative study of the fire‐retardant efficiency of three commercial aryl phosphates—triphenyl phosphate (TPP), resorcinol bis(diphenyl phosphate) (RDP) and bisphenol A bis(diphenyl phosphate) (BDP)—in PC/ABS blends was carried out. The thermal and hydrolytic stability of the fire‐retardant resins, as well as their physical properties, was also studied. The use of RDP and BDP is preferred over TPP because of superior properties, whereas BDP shows better fire‐retardant efficiency, hydrolytic stability, and thermal stability than RDP.
Performance and antioxidant activity of phenol/phosphite antioxidants in synergistic blends in the thermal and photooxidation of high‐density polyethylene (HDPE) film: Influence of zinc stearate
Authors: Allen Norman S. , Enriquez Luis J. , Edge Michele , Liauw Christopher M. , Parrondo Aitor , Fontan Eusebio
Published: April 2004

The influence of zinc stearate (ZnSt) on the thermal and photochemical stabilities of phenolic antioxidant/phosphite combinations has been determined in HDPE by using FTIR analysis. The results show that while under thermal aging the effects are generally antagonistic, under photooxidation the effects are synergistic. The interactions appear to be dominated by the role of complex formation between the phosphites and ZnSt. Such interactions would remove the hydroperoxide effectiveness of the phosphite in thermal oxidation, while under light they could cause stabilization. Derivative UV and FTIR analysis on pre‐melt blends of the additives in solution shows evidence for strong complexation for the phosphite antioxidants. Other acid scavengers such as hydrotalcite and calcium stearate also appear to influence the behavior of phenolic antioxidants in thermal oxidation. The antagonistic effect of zinc stearate was also confirmed following a single pass in an extruder, where for all formulations there was a greater reduction in MFI associated with crosslinking.
New generation of long‐term stabilizers for polyolefins
Authors: Cangelosi Frank , Davis Leonard , Samuels Sari‐Beth
Published: April 2004

Polyolefins are under evaluation for a variety of applications with increasingly stringent requirements, including long‐term exposure outdoors. While the range of physical properties and appearance has been extended by the development of new resins, additives are required to help maintain those properties upon exposure to sunlight, heat, and weather. The benefits of a new generation of light stabilizer with extraordinary efficiency in polyethylene (PE), polypropylene (PP), and other resins are discussed.
PVC wood: A new look in construction
Authors: Chetanachan W. , Sookkho D. , Sutthitavil W. , Chantasatrasamy N. , Sinsermsuksakul R.
Published: April 2004

As a result of the increasing environmental concern for forest protection, there is a rapidly growing demand for alternatives to wood products. PVC wood, which includes PVC foam and PVC/wood flour composite, shows improved performance over wood in the following properties: termite resistance, weathering aging, less moisture absorption, and ease of installation. It can be nailed, screwed, sawed, cut, and glued like wood by conventional tools without any special skills required. Although the bending strength of PVC wood is lower, it can be used for decorative applications, i.e., cornice, door, and siding.
Foaming of rigid PVC/wood‐flour composites through a continuous extrusion process
Authors: Mengeloglu Fatih , Matuana Laurent M.
Published: April 2004

The effects of chemical foaming agent (CFA) types (endothermic versus exothermic) and concentrations as well as the influence of all‐acrylic processing aid on the density and cell morphology of extrusion‐foamed neat rigid PVC and rigid PVC/wood‐flour composites were studied. Regardless of the CFA type, the density reduction of foamed rigid PVC/wood‐flour composites was not influenced by the CFA content. The cell size, however, was affected by the CFA type, independent of CFA content. Exothermic foaming agent produced foamed samples with smaller average cell sizes compared to those of endothermic counterparts. The experimental results indicate that the addition of an all‐acrylic processing aid in the formulation of rigid PVC/wood‐flour composite foams provides not only the ability to achieve density comparable to that achieved in the neat rigid PVC foams, but also the potential of producing rigid PVC/wood‐flour composite foams without using any chemical foaming agents.
PVC — origin, growth, and future
Authors: Braun Dietrich
Published: April 2004

Application of poly(vinyl chloride) (PVC) was first described in a patent in 1913, but only after 1930 did a sustained interest in PVC arise in a number of industrial laboratories. Nowadays PVC is the second thermoplastic resin behind polyolefins with a worldwide capacity of ca. 31 million tons. In its nearly 70 year history, PVC has contributed to much progress in polymer science and technology, e. g., to emulsion and suspension polymerization, detailed analysis of polymer structure, chemistry of stabilization, plasticization, chemical modification, and plastics processing. But PVC also plays an important role in many environmental discussions on polymers, e. g. chlorine chemistry, toxicity of vinyl chloride, or waste and recycling problems. Within the time frame of 70 years, some recent developments in controlled polymerization of vinyl chloride, stabilization, modification of bulk properties and chemical and material recycling of PVC are discussed.
Improving γ‐radiation stability of pvc—a review
Authors: Wang Qi , Nagy Sandor
Published: April 2004

PVC has a significant tendency to degrade under γ irradiation. Therefore, considerable efforts have been made to improve its γ‐radiation stability. The purpose of this review is to summarize recent results in this area, with a special emphasis on the improvement of color stability of PVC‐based materials used in medical applications.
Ecological aspects of polymer flame retardation
Authors: Zaikov G. E. , Lomakin S. M.
Published: April 2004

The practical application of commercial polymer flame retardants can no longer meet present requirements in terms of effectiveness or hazard. The most effective flame retardants used thus far have been halogen‐, phosphorus‐, antimony‐, and heavy‐metal‐based compounds, which, however, have the most environmental impact, either when they perform their action or when they are burned in the incineration of waste containing fire‐retardant polymeric materials. The practical search for new ecologically friendly flame retardants requires cooperation between industry and academia. This paper is devoted to only a few of the new approaches to this very important task: polymer char formers, low‐melting‐glass systems, and morphological modifications.
Low extractable lead stabilizers
Authors: Grossman Richard F.
Published: April 2004

Although lead stabilizers are less soluble and form less soluble reaction products than other types, because of the nature of the U.S. EPA Toxic Characteristic Leaching Procedure extraction, it is often difficult to certify lead‐stabilized scrap as nonhazardous waste. It has been found that lead stabilizers can be blended with additives that lead to reaction products that appear to be extremely insoluble complex phosphates. The results are lead‐stabilized compositions with significantly reduced lead extractability.
Mechanism of organotin stabilization of poly(vinyl chloride). 2: Significance for PVC stabilization of structure and equilibria of alkyltin thioglycolates/chlorides
Authors: Fisch Michael H. , Bacaloglu Radu , Biesiada Keith , Brecker Lawrence R.
Published: April 2004

The stabilization effect of alkyltin thioglycolates was determined by the measurement of discoloration of PVC formulations. The results were interpreted considering the structure of these compounds, their equilibration with alkyltin chlorides, and their postulated association with chlorine atoms at PVC primary particle surfaces.
Plasticizer factors influencing take‐up by PVC resins
Authors: Krauskopf Leonard G. , Godwin Allen D.
Published: April 2004

The ease with which plasticizer is combined with poly(vinyl chloride) resin is a measure of processing characteristics critical in the dry blending of suspension PVC and the gelation of plastisols.

By using commercial grade plasticizers, this study developed predictive equations for the following processing parameters of dialkyl phthalates in PVC:

Relative dry‐blend rates in suspension PVC as a function of plasticizer viscosity.

Relative initial gelation temperatures in plastisols as a function of plasticizer molecular weight and solvating strength.

Relative final gelation temperatures in plastisols as a function of plasticizer solvating strength.

This information allows one to predict the relative processing characteristics of any dialkyl phthalate plasticizer for PVC on the basis of its chemical and physical properties.
Contribution of flow deformation to the shrinkage of injection molded PVC
Authors: Ray E. Harrell , Elleithy Rabeh H. , McFarland Coleen A. , Summers James W.
Published: April 2004

The viscoelastic nature of PVC cannot be ignored during the injection molding process. Strains imposed on the compound during the injection stage display recovery dynamics that are indicative of the temperature at which the strains were imposed. A mathematical model, employing “approximate” time‐temperature modulus relationships, provided the basis for interpreting the shrinkage data. A distribution map of the various relative temperatures attained within the part during injection was determined.
Stabilizers for peroxydicarbonate initiator solutions
Authors: Frenkel Peter , Pettijohn Ted
Published: April 2004

Liquid dialkyl peroxydicarbonates are used as initiators in the PVC industry. Because of the thermal reactivity of these initiators, they require very low temperature storage, shipment, and handling. At temperatures above 10°C, most undergo autoaccelerated self‐induced decomposition. In other words, their self‐accelerating decomposition temperature (SADT) is exceeded. New additives have been discovered which increase the SADT of the initiators. These additives effectively stabilize the products, making them safer to handle, store, and ship. The proprietary additives and a mechanism of stabilization are discussed. We also include a section concerning the implications these products have for future initiator formulation.
Study of some parameters responsible for the efficiency of hindered amine light stabilizers
Authors: Geuskens G. , McFarlane D. M.
Published: April 2004

The photooxidation of a styrene‐butadiene‐styrene block copolymer previously hydroperoxidized by reaction with singlet oxygen has been studied by measuring the increase of the carbonyl absorbance at 1720 cm−1. Five different hindered amine light stabilizers (HALS) have been introduced into the polymer by diffusion from methanolic solutions, and their efficiencies as inhibitors of the photooxidation have been compared. The sequence of efficiency observed is:

tert. amine > sec. amine > amino ether

Under the experimental conditions used HALS are localized preferentially in oxidized regions of the polymer, and their efficiency can be correlated with their ability to catalyze the decomposition of clustered hydroperoxides. As a consequence, HALS are oxidized to nitroxy radicals that are the actual inhibitors of the photooxidation. A high local concentration of HALS in oxidized regions of the polymer also contributes to their efficiency, and this effect justifies the observation that some tertiary amines are more efficient than others.
Blends of poly(vinyl chloride) with plasticized polyaniline
Authors: Pielichowski Krzysztof , Pearce Eli M.
Published: April 2004

A series of poly(vinyl chloride) (PVC)/polyaniline (PANI) blends plasticized and protonated simulataneously by bis(2‐ethylhexyl) hydrogen phosphate, bis(4‐nitrophenyl) phosphate, diphenyl phosphate, or dibenzyl phosphate was prepared by a mass homogenization technique. Thermal analysis studies by means of thermo‐gravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that PVC/PANI blends with bis(2‐ethylhexyl) hydrogen phosphate were characterized by the highest thermal stability values. Kinetic analysis of the decomposition process by the isoconversional Friedman method showed that the activation energy did not change substantially over the broad conversion range; further advanced kinetic analysis by a nonlinear regression method revealed that the kinetic function that was the best approximation for the experimental data was based on a reaction of nth order.
Fate of PVC polymer, plasticizers, and stabilizers in landfilled waste
Authors: Mersiowsky Ivo
Published: April 2004

End‐of‐life PVC products are predominantly disposed of with construction waste or with municipal solid waste in sanitary landfills. This waste management option is currently subject to debate because of environmental issues. A material and substance flow analysis was conducted to estimate the quantitative relevance of PVC products and their constituents in municipal solid waste. Landfill simulation assays demonstrated the long‐term behavior of PVC products and the fate of additives under landfill conditions. The PVC polymer was found to be stable. A loss of plasticizers may occur in case of insufficient compatibility with the PVC compound coupled with microbial consumption at the PVC product surface. Losses of stabilizers are generally restricted to transient leaching from the product surface. Plasticized products show a somewhat stronger inclination to release their stabilizers. The findings indicated that additional measures specifically directed at post‐consumer PVC waste in landfills are not necessary.
Weatherability of plastics compared at different exposure locations
Authors: Summers James W. , Rabinovitch Elvira B.
Published: April 2004

The mechanisms of the weathering of plastics are often initiated by damaging radiation from the sun or by the hydrolysis of ester, carbonate, or amide groups in the polymer. The Arizona exposure is sunny and dry, while the Ohio exposure is less sunny, wetter, and has more acid rain. Arizona emphasizes ultraviolet light exposure; Ohio emphasizes hydrolysis. This paper examines the weatherability of vinyl, ABS, acrylic, and SAN/EPDM polymers in these two locations. Color retention, original impact, and impact retention are evaluated.
Additive interactions in the stabilization of film grade high‐density polyethylene. Part I: Stabilization and influence of zinc stearate during melt processing
Authors: Parrondo Aitor , Allen Norman S. , Edge Michele , Liauw Christopher M. , Fontán Eusebio , Corrales Teresa
Published: April 2004

The melt stabilization activity of some of the most commercially significant phenolic antioxidants and phosphites (alone and in combination), without and with zinc stearate, was studied in high‐density polyethylene (HDPE) produced by Phillips catalyst technology. Multiple pass extrusion experiments were used to degrade the polymer melt progressively. The effect of stabilizers was assessed via melt flow rate (MFR) and yellowness index (YI) measurements conducted as a function of the number of passes. The level of the phenolic antioxidant remaining after each extrusion was determined by high‐performance liquid chromatography (HPLC). Phenolic antioxidants and phosphites both improved the melt stability of the polymer in terms of elt viscosity retention; the influence of zinc stearate was found to be almost insignificant. However, phosphites and zinc stearate decreased the discoloration caused by the phenolic antioxidants. A correlation was found between the melt stabilization performance of phosphites and their hydroperoxide decomposition efficiency determind via a model hydroperoxide compound. Steric and electronic effects associated with the phosphorus atom influenced the reactivity towards hydroperoxides. Furthermore, high hydrolytic stability did not automatically result in lower efficiency. Besides phosphite molecular structure, stabilization activity was also influenced by the structure of the primary phenolic antioxidant and the presence of zinc stearate.
Additive interactions in the stabilization of film grade high‐density polyethylene. Part II: Stabilization during long‐term service
Authors: Parrondo Aitor , Allen Norman S. , Edge Michele , Liauw Christopher M. , Fontán Eusebio
Published: April 2004

In the second part of this study, the performance of phenol/phosphite/zinc stearate packages and the contribution of each additive to the long‐term thermal stabilization and photostabilization were evaluated in high‐density polyethylene produced by using Phillips catalyst technology. Infrared spectroscopy, ultraviolet spectroscopy, and yellowness index measurements were used to establish the performance of the different additive packages. The HPLC analysis of dichloromethane extracts of the polymer was carried out after melt processing in order to determine the amount of phenolic antioxidant remaining in the samples. The long‐term thermal stabilization was dependent only upon the phenolic antioxidant concentration, whereas both phenolic antioxidants and phosphites contributed directly to photostabilization. Zinc stearate did not show any significant influence on the stabilization under either thermooxidative or photooxidative conditions.
Some aspects of the thermal degradation of PVC. Crosslinking of macromolecules
Authors: Yanborisov V. M. , Minsker K. S. , Zaikov G. E. , Zaikov V. G.
Published: April 2004

Direct experimental proof is presented that crosslinking of macromolecules during the thermal degradation of PVC proceeds with participation of blocks of conjugated double bonds formed upon activation by carbonylallyl groups.
Edna St. Vincent Millay and Anne Sexton: The Disruption of Domestic Bliss
Authors: MICHAILIDOU ARTEMIS
Published: April 2004

Popular perceptions of Edna St. Vincent Millay do not generally see her as a poet interested in so-called “domestic poetry.” On the contrary, Millay is most commonly described as the female embodiment of the rebellious spirit that marked the 1920s, the “New Woman” of early twentieth-century feminism. Until the late 1970s, the subject of domesticity seemed incompatible with the celebrated images of Millay's “progressiveness,” “rebelliousness,” or “originality.” But then again, by the 1970s Millay was no longer seen as particularly rebellious or original, and the fact that she had also contributed to the tradition of domestic poetry was not to her advantage. Domesticity may have been an important issue for second-wave feminists, but it was discussed rather selectively and, outside feminist circles, Millay was hardly ever mentioned by literary critics. The taint of “traditionalism” did not help Millay's cause, and the poet's lifelong exploration of sexuality, femininity and gender stereotypes was somehow not enough to generate sophisticated critical analyses. Since Millay seemed to be a largely traditional poet and a “politically incorrect” feminist model, second-wave feminists preferred to focus on other figures, classified as more modern and more overtly subversive. Scholarly recognition of Millay's significance within the canon of modern American poetry did not really begin until the 1990s.
Edith Wharton's Higher Provincialism: French Ways for Americans and the Ends of The Age of Innocence
Authors: NOWLIN MICHAEL
Published: April 2004

“How much longer,” Edith Wharton lamented in a July 1919 letter to Barrett Wendell, “are we going to think it necessary to be ‘American’ before (or in contradistinction to) being cultivated, being enlightened, being humane, & having the same intellectual discipline as other civilized countries?” She was having her publishers send him her most recent book, French Ways and Their Meaning (1919), a collection of essays written in large part to instruct her compatriots in the ways of an exemplary civilization. Wharton's complaint found its way into her 1920 novel The Age of Innocence, which she began working on soon after French Ways was published; though in this instance it was voiced from a different quarter and had potentially radical implications.
XPath-logic and XPathLog: A logic-programming style XML data manipulation language
Authors: MAY WOLFGANG
Published: April 2004

We define XPathLog as a Datalog-style extension of XPath. XPathLog provides a clear, declarative language for querying and manipulating XML whose perspectives are especially in XML data integration. In our characterization, the formal semantics is defined wrt. an edge-labeled graph-based model, which covers the XML data model. We give a complete, logic-based characterization of XML data and the main language concept for XML, XPath. XPath-Logic extends the XPath language with variable bindings and embeds it into first-order logic. XPathLog is then the Horn fragment of XPath-Logic, providing a Datalog-style, rule-based language for querying and manipulating XML data. The model-theoretic semantics of XPath-Logic serves as the base of XPathLog as a logic-programming language, whereas also an equivalent answer-set semantics for evaluating XPathLog queries is given. In contrast to other approaches, the XPath syntax and semantics is also used for a declarative specification how the database should be updated: when used in rule heads, XPath filters are interpreted as specifications of elements and properties which should be added to the database.
PROGRAMMING PEARL: Enhancing a search algorithm to perform intelligent backtracking
Authors: BRUYNOOGHE MAURICE
Published: April 2004

This paper illustrates how a Prolog program, using chronological backtracking to find a solution in some search space, can be enhanced to perform intelligent backtracking. The enhancement crucially relies on the impurity of Prolog that allows a program to store information when a dead end is reached. To illustrate the technique, a simple search program is enhanced.
Speedup of logic programs by binarization and partial deduction
Authors: HRŮZA JAN , šTĚPÁNEK PETER
Published: April 2004

Binary logic programs can be obtained from ordinary logic programs by a binarizing transformation. In most cases, binary programs obtained this way are less efficient than the original programs. (Demoen, 1992) showed an interesting example of a logic program whose computational behaviour was improved when it was transformed to a binary program and then specialized by partial deduction. The class of B-stratifiable logic programs is defined. It is shown that for every B-stratifiable logic program, binarization and subsequent partial deduction produce a binary program which does not contain variables for continuations introduced by binarization. Such programs usually have a better computational behaviour than the original ones. Both binarization and partial deduction can be easily automated. A comparison with other related approaches to program transformation is given.
Time dependent radial diffusion modeling of relativistic electrons with realistic loss rates
Authors: Shprits Y. Y. , Thorne R. M.
Published: April 2004

Model simulations are compared to the typically observed evolution of MeV electron fluxes during geomagnetic storms to investigate whether radial diffusion alone can account for the observed variability and to estimate the effect of electron lifetimes. We demonstrate that knowledge of lifetimes is crucial for understanding the radial structure of the storm‐time radiation belts and their temporal evolution. Our model results suggest that outer zone lifetimes at 1 MeV are on the order of few days during quite‐times and less than a day during storm‐time conditions. Losses outside plasmasphere should be included in the modeling of electron fluxes since effective lifetimes are much shorter than that of plasmaspheric losses. Simulations with variable outer boundary conditions show that the depletion of the main phase relativistic electron fluxes at L ≤ 4 can not be explained only by variations in fluxes near geosynchronous orbit and require local lifetimes as short as 0.5 day. Radial diffusion alone is unable to account for either the gradual build up of relativistic electron fluxes or the maxima in phase space density near L = 4 − 5 observed during the recovery phase of many storms, which suggests that an additional local acceleration source is also required.