bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of an LPG explosion and fire
Authors: Rodante Thomas V. 
Published: April 2004

AbstractIn September 1997, an LPG release occurred at the Hindustan Petroleum Corporation, Ltd. refinery in Visakhapatnam, India. The resulting explosion and fire destroyed most of the facility's administrative buildings, numerous LPG storage vessels, processing units, and an adjacent petroleum liquid storage terminal. Fifty‐six people were declared dead, but the fatality number could have been as high as 3 times the official estimate. Property damage was estimated at US $15 million.It is known that a leak occurred during receipt of LPG cargo from a pressurized ship. The subsequent vapor cloud spread throughout the refinery tank farm, administrative complex, utilities area, and at least one process unit before eventually finding an ignition source. The investigation team developed numerous release theories. However, none of these theories could be substantiated by first hand witnesses' testimonies since all personnel directly involved in the tank filling operation were killed. Vapor cloud dispersion computer modeling was used to evaluate the credibility of various release scenarios. This paper discusses the events leading up to the explosion, the damages sustained, and compares quantitative dispersion modeling results to the physical damage and witness testimony obtained during the investigation.
Effects of plate impingement on the flammable volume of fuel jet releases
Authors: Sposato Christina , Tamanini Francesco , Rogers William J. , Mannan M. Sam 
Published: April 2004

AbstractThe effects of plate impingement on the flammable mixture produced by a fuel jet release were modeled with a commercial computational fluid dynamics (CFD) code. First, the CFD code was used to simulate the release of a free turbulent jet to assure that the code agreed with established trends. Equations were derived to determine the volume of the free jet above the lower flammable limit. The code was then used to model a jet confined by a wall or a circular plate. Computer simulated concentration profiles of the source fluid and air mixtures were analyzed to determine mixture volumes above the lower flammable limit. The flammable mixture volume was normalized and determined as a function of plate radius and distance.
Methodology and software for assessing reactivity ratings of chemical systems
Authors: Kossoy Arcady , Hofelich T. 
Published: April 2004

AbstractTo resolve various problems in creating a process, or conducting stability analysis, and/or hazard assessments, one needs t o know the reactivity of a chemical system. The National Fire Protection Association (NFPA) requires use of a reactivity rating number to describe such reactivity potentials as thermal stability, interaction with water, and gas generation. For assessing thermal stability of a substance, NFPA has recently accepted a new quantitative approach based on the idea of “Instantaneous Power Density.” Though it has many advantages compared to the largely qualitative previous approach, the new method has one serious draw‐back—it doesn't take into account the peculiarities of such complex cases as self‐accelerating or multi‐stage reactions. This, in turn, can lead to a less‐than‐safe, or unsafe, design.In this paper, we propose a method to generalize the concept of instantaneous power density by considering the maximal power density as the quantitative measure of the reactivity, allowing one to take proper account of kinetic complexity. We also briefly discuss the ReRank software which was developed to assess reactivity ratings in general, and specifically, to calculate reactivity rating numbers.
Method for estimating decomposition characteristics of energetic chemicals
Authors: Chervin Sima , Bodman Glenn T. 
Published: April 2004

AbstractExperimental data on the decomposition characteristics of approximately400 chemicals, representing various classes of energetic materials, were summarized by chemical class and statistically analyzed. Average decomposition characteristics, such as energy of decomposition and decomposition onset temperature, were determined for chemical classes containing the following energetic groups: nitro, nitroso, N‐oxide, oxime, hydroxylamine, tetrazole, azide, triazene, triazole, diazo, azo, hydrazine, and perchlorate. Additional statistical information is presented for each chemical class, such as number of chemicals analyzed, ranges, and standard deviations for the decomposition parameters analyzed. For chemical classes containing an energetic group attached to an aromatic ring, the presence and position of another substituting group in the ring can significantly influence the decomposition onset temperature. The study summarizes the list of activating and deactivating functional groups, and the positions in the ring where the strongest activation or deactivation occurs. The authors also recommend a method for estimating decomposition parameters of new chemicals.
Folk theories of “inquiry:” How preservice teachers reproduce the discourse and practices of an atheoretical scientific method
Authors: Windschitl Mark 
Published: April 2004

AbstractDespite the ubiquity of the term “inquiry” in science education literature, little is known about how teachers conceptualize inquiry, how these conceptions are formed and reinforced, how they relate to work done by scientists, and if these ideas about inquiry are translated into classroom practice. This is a multicase study in which 14 preservice secondary science teachers developed their own empirical investigations—from formulating questions to defending results in front of peers. Findings indicate that participants shared a tacit framework of what it means to “do science” which shaped their investigations and influenced reflections on their inquiries. Some facets of the participants' shared model were congruent with authentic inquiry; however, the most consistent assumptions were misrepresentations of fundamental aspects of science: for example, that a hypothesis functions as a guess about an outcome, but is not necessarily part of a larger explanatory system; that background knowledge may be used to provide ideas about what to study, but this knowledge is not in the form of a theory or other model; and that theory is an optional tool one might use at the end of a study to help explain results. These ideas appear consistent with a “folk theory” of doing science that is promoted subtly, but pervasively, in textbooks, through the media, and by members of the science education community themselves. Finally, although all participants held degrees in science, the participants who eventually used inquiry in their own classrooms were those who had significant research experiences in careers or postsecondary study and greater science‐content background. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 481–512, 2004
Super tough PVC alloy with high heat distortion temperature
Authors: Huynh‐Ba Gia 
Published: April 2004

AbstractPoly(vinyl chloride) (PVC) is an inexpensive commodity polymer with many good properties such as flame retardancy and rigidity. Unfortunately, its heat distortion temperature is around 75°C. To increase its toughness, plasticizers or elastomers are added with a loss in both heat distortion temperature (HDT) and flame retardancy. Low molecular weight imidized acrylic having a Tg < 130°C when added to PVC shows a modest gain in HDT but at the expense of toughness. Inclusion of a rubber to improve the toughness of the acrylic modified composition lowers its HDT as well as its flame retardancy. The technology reported here details a method utilizing an “alloy” polymer added to PVC to increase both its toughness and HDT.
Poly (α‐methylstyrene‐styrene‐acrylonitrile) as a heat deflection additive for PVC: Physical and rheological properties
Authors: Zerafati Saeid 
Published: April 2004

AbstractPoly(α‐methylstyrene‐styrene‐acrylonitrile) (AMSAN) is an additive used to improve the heat deflection temperature of PVC. The effect of its addition on the HDT of a typical injection molding formulation is studied. Other physical properties like impact strength, yield strength, modulus of elasticity, and viscosity are also reported. It is shown that HDT and impact strength are decoupleable based on the amount of AMSAN and impact modifier in the formulation. Calculation of the required percentage of heat distortion additive and impact modifier for a typical injection molding application are demonstrated.
Radiation sterilization compatibility of medical packaging materials
Authors: Shang Sherwin , Ling Michael T. K. , Westphal Stanley P. , Woo Lecon 
Published: April 2004

AbstractWe have examined gamma sterilization compatibility for many of medical packaging materials. Techniques used include thermal analysis, physical testing, optical property evaluations, and failure analysis. For a variety of PVC formulations, gamma radiation often leads to discoloration. This results from conjugated poly‐ene sequences formed through dehydrohalogenation degradation during ionizing radiation. In addition to unacceptable color formation, excessive pH shifts and high extractables are often observed. For most polylefins, radiations was found to deplete the antioxidant package and lead to discoloration and/or mechanical failures. For polypropylenes, the degradation can lead to the well‐publicized catastrophic failures during post radiation shelf life storage. These examples and methods to ensure radiation compatibility and shelf‐life stability are presented.
The impact of metallocenes on PVC
Authors: Wilson Robert B. 
Published: April 2004

AbstractPVC has been under attack from environmental groups for some time. Whatever the merits of the environmentalists' arguments, PVC has resisted this attack in many applications because of a unique combination of performance and price. As a result, the PVC industry has been experiencing a period of good growth. Metallocene based polyolefin resins are the first materials that appear to be a threat to that position. Recent reports of the performance of metallocene resins have demonstrated an incredible performance boost when compared with conventional PE or PP. This talk will examine the threat from the development of metallocenes.
Recycling durable vinyl products
Authors: Wisner D'Lane 
Published: April 2004

AbstractThis is a description of the key aspects that have made a vinyl siding recycling project in Grand Rapids, Michigan, successful to date. Although Grand Rapids is hoped to be a template for other recycling projects there are some unique parts of the project that other regions of the country or even the city next door to Grand Rapids may not be able to duplicate. It would not be advisable at this point in time to advocate a nation‐wide vinyl siding recycling program based on the early results from Grand Rapids. On the other hand, the day may come when recycling the waste from residential construction sites (including the vinyl products) will be more widespread. At any rate, what Grand Rapids has proven is that vinyl as a material is ready for recycling.
The Dilemma of flexible PVC from an independent compounder's perspective
Authors: Lederer Bertram 
Published: April 2004

AbstractFlexible PVC compounds produced by the Plastics Division of Teknor Apex are used in most major end‐use markets. Our materials are molded and extruded for applications in wire and cable, automotive, medical, building and construction, appliances, toys, food packaging, housewares, power tools, recreational products, and many other industries. This involvement with diverse markets gives us a wideranging perspective on attitudes towards flexible PVC among people involved in product design, material specification, purchasing, sales and marketing, processing, and other important functions at corporations large and small.“The Dilemma of Flexible PVC” reflects what we see, from our conversations and business dealings with these customers, as a critical crossroads for the material. On the one hand, we see many new opportunities for greater market penetration by flexible PVC because of dynamic new product development in the industry and continuing cost/performance advantages compared to other thermoplastics.On the other hand, we are hearing escalating concerns from the marketplace about the environmental friendliness and safety of flexible PVC that may threaten these opportunities.These negative attitudes toward PVC are certainly not new, but we are hearing them with increasingly greater frequency. They are coming from design engineers and other material specifiers developing new applications, and from people involved in long‐standing flexible PVC applications.
Beyond color: Modifiers and additives that affect appearance
Authors: Burgess Alan 
Published: April 2004

AbstractIn today's globally competitive market, product distinction is a key to success. Therefore, the ability to produce unique and appealing special effects becomes a powerful marketing tool for savvy manufacturers of plastic and other parts. High shelf‐appeal not only positions a product to attract the eye of the consumer, but also supports the impression that a product is of higher quality, a more playful or elegant design, or represents the latest that technology has to offer. When it comes to special effects, the buying public is insatiable and market demand is hindered only by the imagination of manufacturers and consumers. The ability of current color technology to support this demand requires that additive suppliers, color formulators, and plastics processors work in close partnership. This paper surveys the development of traditional and newer special effects technologies and describes some of the challenges encountered in developing them.
The structure of lead stabilizers. 2: Basic salts of inorganic acids
Authors: Grossman Richard F. , Krausnick Dale 
Published: April 2004

AbstractFTIR and NMR measurements were used to infer structural formulas for the heat stabilizers dibasic lead phosphite, tribasic and tetrabasic lead sulfates, and basic lead carbonate. These compounds are not the customarily written double salts of lead oxide or hydroxide, but distinct species capable of rapid HCI neutralization.
Phosphate ester additives as melt flow modifiers in ABS
Authors: Moy Paul Y. 
Published: April 2004

AbstractMelt flow modification of plastic composites is becoming increasingly important in the design of thin wall moldings. One approach to enhancing melt flow properties is by using phosphate esters. While phosphate ester plasticizers have been used for many years in flexible vinyl applications, the recent development of oligomeric phosphate esters offers high stability, low fugitive characteristics and melt flow enhancement to these demanding situations at a modest level. This paper discusses the influence of these additives to mechanical and melt flow properties in different process regimes for ABS.
Effect of physical aging on the impact retention and heat distortion temperature of vinyl products
Authors: Zerafati Saeid , Black Janine 
Published: April 2004

AbstractPhysical properties of polymers change with time. Exposure of amorphous polymers to high temperature will reduce their free volume, which in turn increases their heat distortion temperature and decreases their impact strength. Heat distortion additives, such as poly(α‐methylstyrene‐styrene‐acrylonitrile) (AMSAN), enhance the glass transition temperature of PVC and help in the impact retention of the polymer by slowing down the aging process. In this paper, physical aging of PVC is explored, effect of annealing time and temperature on the impact strength and HDT is reported, and conclusions regarding the retention of impact resistance upon aging are drawn.
Mechanical properties of extrusion‐foamed rigid PVC/wood‐flour composites
Authors: Mengeloglu Fatih , Matuana Laurent M. 
Published: April 2004

AbstractThis study was conducted to characterize the mechanical properties of extrusion‐foamed neat rigid PVC and rigid PVC/wood‐flour composites by using endothermic and exothermic chemical foaming agents (CFAs). The specific elongation at break (ductility) of the samples was improved by foaming, while the opposite trend was observed for the tensile strength and modulus of the samples, regardless of the chemical foaming agent type. In addition, experimental results indicated that foaming reduced the Izod impact resistance of both neat rigid PVC and rigid PVC/wood‐flour composites but that this reduction was not statistically significant for the composites. A comparison between batch microcellular processing and extrusion foam processing was made, which demonstrated that foams with very fine cells (microcellular processed) exhibit better impact strength than foams with larger cells (extrusion processed with CFAs).
Confirming the pinking mechanism of PVC profiles in mild climatic conditions
Authors: Lemaire Jacques , Siampiringue Narcisse , Girod Nicolas , Delprat Patrick , Parmeland Georges , Macdonald Neil , Spriet Christine 
Published: April 2004

AbstractPinking of TiO2‐pigmented PVC can be observed for profiles exposed to the mild environmental conditions of northern European countries. In a previous paper, the pinking phenomenon was accounted for at the molecular level by the formation of polyene sequences, which are not completely photooxidatively bleached in conditions of oxygen starvation. This causation has been confirmed by exposing to visible light in a SEPAP 12.24 apparatus profiles in which pinking was produced during 4 year‐weathering in N.W. France. The fast phototransformations in visible light of chloropolyenes in trans‐configurations leading to α‐chloropolyenes in cis‐configurations accounts for the conversion of pinking into limited graying. It appears that the first and more intense graying observed after the initial exposure to UV and visible light of profiles in the SEPAP 12.24 can be essentially attributed to the photoreduction products of lead stabilizers. Graying could be bleached through thermooxidation at 65°C, could not be converted into pinking, and has no environmental relevance.
Coprecipitates of dibasic lead phthalate and tribasic lead sulfate
Authors: Grossman Richard F. 
Published: April 2004

AbstractCoprecipitates of dibasic lead phthalate and tribasic lead sulfate tend to crystallize with the latter forming the core of a core/shell structure. The reactivity of this structure towards hydrolysis of ester plasticizers is considerably lower than that of physical blends of the basic lead salts.
Effect of processing parameters on fusion and mechanical properties of a twin‐screw extruded rigid PVC pipe
Authors: Moghri M. , Garmabi H. , Akbarian M. 
Published: April 2004

AbstractThe effect of varying mass temperature and screw speed on the fusion level and mechanical properties of a rigid PVC pipe produced by a twin‐screw extruder has been investigated. Differential Scanning Calorimetry (DSC) and capillary rheometry have been used to determine pipe fusion levels. While yield stress was shown to be completely insensitive to fusion level, a very distinct maximum of falling weight and notched Charpy impact strengths and elongation at break was observed at moderate fusion level. Short‐term burst strength values increased with degree of fusion while hydrostatic internal pressure tests revealed optimum resistance for pipes of varying fusion level. The effect of processing temperature on fusion in the Brabender Plasticorder was also examined.
Impact modification of polypropylene
Authors: Rabinovitch Elvira B. , Summers James W. , Smith Greg 
Published: April 2004

AbstractThis paper compares the modification mechanism provided by ethylene‐octene (EO) copolymer to that of ethylene‐propylene‐diene terpolymer (EPDM) rubber. Within the limits of this study, the highest impact strength was achieved at 30–40% rubber content, regardless of the rubber type. An increase in rubber melt viscosity resulted in overall greater impact strength. At the optimum concentration, the high‐viscosity (MFI = 1 to 5) EO rubber provided modification mainly via a crazing mechanism, while the EPDM rubber functioned by energy dissipation through the three‐dimensional network structure formed with the polypropylene matrix. This paper also discusses the effects of the processing conditions on the physical properties of PP/EPR copolymer. An increase in processing temperature and screw speed resulted in a reduced number of discrete rubber particles and nearly no or very slight increase in impact strength, but a very significant reduction in tensile strength and tensile modulus.
How about alternatives to phthalate plasticizers?
Authors: Krauskopf Leonard G. 
Published: April 2004

AbstractPhthalate plasticizers have historically served as the preferred plasticizers to impart flexibility to PVC and several other polar polymers. They provide a desirable balance of cost and performance properties. Their acceptable and safe use is unmatched in medical appliances, food processing, and packaging applications, as well as in many other end uses. Potential alternatives do not have the historical record of acceptable performance found with phthalate plasticizers. Nevertheless, the “Precautionary Principle” has caused certain segments of society to clamor for alternates to phthalate plasticizers. This paper reviews known “non‐phthalate” plasticizers and provides comparisons to the traditional “General Purpose” (GP) phthalate plasticizers; “General Purpose” plasticizers are those that impart optimum overall performance properties in PVC at lowest cost.
Evaluation of novel derivatives of 2,2‐dimethyl‐1,3‐diaminopropane as thermal and UV stabilizers in medium‐density polyethylene films
Authors: Berlanga Duarte M. L. , Rosales Jasso A. , Allen N. S. 
Published: April 2004

AbstractNovel oligoalkylenamines (Additive A2) were obtained by the reaction between 2,2‐dichloropropane and 1,3‐diamino‐2,2‐dimethylpropane. The presence of partially hindered amine groups in the product was confirmed by NMR. The amines were evaluated as thermal and UV stabilizers in medium‐density polyethylene (MDPE) films containing Irganox 1330 (PEA2Ir), Chimassorb 944 (PEA2CH), or a mixture of Irganox 1330 and Chimassorb 944 (PEA2M) by following changes in the concentration of carbonyl groups in the IR region of 1718 cm−1. Under UV aging, the amine mixture A2 interacts with Chimassorb 944 in a synergistic way that is explained by the quenching of charge transfer complexes. Under thermal aging, a synergistic effect was observed in formulations containing Irganox 1330. It is still not clear if alkyl ethers of hydroxylamines from A2 are more stable at 100°C or if their nitroxyl radicals are more reactive than the corresponding species from Chimassorb 944.