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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 297-301 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Baker-Strehlow methodology was developed to provide an objective approach to prediction of blast pressures from vapor cloud explosions. The complete methodology was first published in 1994 [1]. Since then, it has evolved through ongoing research and use in VCE hazard analyses, facility siting studies and accident investigations. This article gives a brief overview of a paper on recent developments in the Baker-Strehlow methodology presented at the 31st Loss Prevention Symposium in Houston on March 9-13, 1997. Because the entire paper is too lengthy to be presented here, the following discussions may be lacking in some details. A copy of the complete paper can be obtained from the American Institute of Chemical Engineers (AIChE).Since the Baker-Strehlow method was first published, it has been used extensively in VCE hazard assessments in refineries and chemical plants. As expected, many practical lessons have been learned during the course of the hazard assessments, and the Baker-Strehlow method has evolved as a result. The changes have been evolutionary, not revolutionary. In keeping with the goals of the original study in which the methodology was developed, all changes have been incorporated with the intent of achieving an objective methodology to provide consistent prediction of VCE blast effects.The revisions to the Baker-Strehlow method resulting from experience gained during plant walk-downs and hazard assessments include: Systematic identification of “potential explosion sites” or “PESs,”Selection of the level of confinement for mixed zones of 2D and 3D confinement,Deciding on flame expansion when confinement is elevated above the vapor cloud,Selecting the reactivity for a fuel that is a mixture of fuels with differing reactivities,Predicting blast loads when there are multiple PES's within a vapor cloud considering different ignition source locations.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 20-22 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most audits try to look at a representative selection of the plant procedures and equipment. An alternative is a survey, a look in depth at selected procedures (such as those for testing alarms and trips, issuing permits-to-work, controlling modifications, taking samples or testing relief devices) or selected equipment (such as level glasses or equipment for handling LPG). If the procedure or equipment is well-chosen, surveys may make a bigger contribution to safety, per person-hour, than a conventional audit.
    Additional Material: 1 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 86-97 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Regulatory issues related to material safety have made the accurate measurement and/or prediction of flash points essential. The flash point is one of the major physical properties used to determine the fire and explosion hazards of a liquid. Flash points are used by virtually all governmental entities worldwide to define “flammable” and “combustible” materials for shipping and safety regulations.A model is described here for the calculation of closed cup flash points for multicomponent, single liquid phase, mixtures. The model is based upon rigorous vapor/liquid equilibrium calculations supplemented with information about the lower flammable limits (LFL's) and heats of combustion (ΔHc's) for the mixture's constituent components. The closed cup flash points predicted with this model are typically within ± 5°C of the experimentally reported values. Such a model is useful as a means of verifying experimental data and as a tool for screening product formulations prior to experimental flash point determination. The model should considerably enhance the safety evaluation portion of the product development cycle, thus leading to shortened product time-to-market cycles. While flash points calculated with this model are in excellent agreement with experiment, experimental determination is still encouraged for critìcal safety applications.
    Additional Material: 15 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 134-137 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: National Advisory Committee's Acute Exposure Guideline Levels (AEGLs) for ammonia are critically evaluated. The technical bases for concern about AEGL-2 and AEGL-3 values derived by the committee are summarized recommendations made.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 127-133 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An explosion and flash fire in a fixed bed reactor occurred at a municipal wastewater treatment plant (WWTP). Two employees were injured in the accident. The accident occurred in an ozone treatment building where ozone was used to treat odors from the offgas of the sludge concentration units. Excess ozone manually was routed to the fixed bed reactor (ozone destruct unit) where the ozone is catalytically transformed into oxygen before being discharged to the atmosphere.An investigation of the accident was conducted to determine the root cause of the explosion and flash fire and identify corrective actions which the WWTP management could undertake to prevent a recurrence. This investigation included site inspections, interview with the injured employees, sampling and analysis of various materials, an explosion dynamics analysis, and a root cause analysis.It was concluded that cooling oil from one of the ozone generation units entered the main ozone gas line due to a crack in one of the reactor's dielectric tubes. The cooling oil was vented into the ozone destruct unit when an employee opened a ball valve on the main ozone gas line. The cooling oil, essentially a saturated hydrocarbon mixture, reacted exothermically when it contacted the manganese dioxide catalyst. The exothermic reaction resulted in an explosion which propelled the access panel outwards and dispersed the catalyst pellets. A flash fire followed the explosion. The flash fire burned two employees and caused thermal damage to a nearby control panel.Although this accident was the first of its kind at this facility, this was not the first time that the ozone generator had experienced a failure of a dielectric tube. Thus, there was a significant probability that a dielectric tube failure could leak cooling oil into the main ozone gas line. This failure event could, in turn, result in another explosion and flash fire. The WWTP staff neither designed nor fabricated the ozone generator-destructor system. Therefore, it did not seem appropriate for the WWTP staff to modify the ozone system. Instead, it was recommended that the ozone destruct unit be taken out of service. The WWTP management acted on this recommendation.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 171-175 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An explosion occurred in a petroleum product storage tank at a refinery. The liquid petroleum product was a heavy oil used as an asphalt extender. There were no injuries, but the cleanup was costly. The storage tank was one of several which received the product stream from a dehydration unit. The accident occurred shortly after the refinery was brought back on-line following a shutdown for schduled maintenance.This was the first incident of this kind to occur at this facility. Analysis of the process data and eyewitness observations indicated that the dehydration tower, which was supposed to be maintained at a minimum of 100°C during the shutdown, was allowed to drift below 100°C for an unknown period of time. This deviation enabled liquid water to enter the storage tank. Three operational factors contributed to the accident. Corrective actions were recommended to prevent a recurrence of a similar incident.
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 184-189 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dust explosions have been with us for a long time. The first record of a dust explosion occurred in Turin, Italy, on December 14, 1785 [1]. The detailed record of this event is left to us by Count Morozzo. The event took place in Mr. Giacomelli's bakery. We know from his account that the weather was unseasonably dry, that a boy who worked in the bakery was using a shovel to stir and transfer the flour to a chute from a store room to the bakery and he had a lighted lamp to work by. The rest, as the saying goes, is history. No one was killed, and the building was saved by the sagacious fact of having plenty of windows. Since that first record, of course, there have been many explosions with much loss of life and significant economic consequences.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 190-195 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The RSST DIERS vent sizing methodology is revised to provide realistic design equations for reactive systems consistent with available large-scale experience. Using easy to obtain RSST data such as rate of temperature rise and rate of pressure rise excellent agreement is illustrated for hybrid, vapor and gassy reactive systems.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 196-199 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: From the 1960s onwards, the chemical and oil industries developed and used a number of new safety techniques which, in time, became second nature to those who applied them. They included the use of QRA for deciding priorities, Hazop and audits for identifying problems, inherently safer design for avoiding hazards, and more thorough investigation of incidents for identifying underlying causes. However, it has not yet become second nature to remember the accidents of the past and the actions needed to prevent them happening again.I joined industry in 1944 and moved to production in 1952. Then, and for at least 15 years afterwards, safety was a non-technical subject that could be left to arts graduates and elderly foremen. There was concern that people should not be hurt - great attention was paid to the lost-time accident rate - but there was no realization, that it was a subject worthy of systematic study by experienced technologists.This view changed at the end of the 1960s. A new generation of plants had been built, operating at higher temperatures and pressures and containing larger inventories of hazardous chemicals; the result was a series of fires and explosions and a worsening fatal accident rate. Figure 1 shows the situation in ICI, at the time the UK, s largest chemical company. Other companies experienced a similar state of affairs.As a result in 1968, I was appointed one of the company's first technical safety advisers, an unusual appointment at the time for someone with my experience, and if the reason for my appointment had not been so obvious I would have wondered what I had done wrong. I and my colleagues tried to apply the same sort of systematic thinking to safety that we applied in our other professional work. We developed some new concepts and techniques and adopted others. A common feature of our ides, realized only in restrospect, was that they consisted of more than mere problem-solving techniques. Once people had got used to these new concepts and used them a few times, they began to look at a whole range of problems in a different way.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. W3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 259-262 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Case histories of 65 incidents in runaway reactions and emergency relief in Taiwan were analyzed and classified into several categories according to their causes, materials involved, equipment types, reaction types, and ignition sources. The cases in reactors and storage tanks were examined in more detail owing to the higher probability or larger potential hazard in these two types of equipments. The most common consequence of the incidents are explosions, fires, and atmospheric release of toxic chemicals. The most severe case was a thermal explosion from an organic peroxide storage area which caused the death of 33 persons. Popping and direct releasing of process chemicals to the atmosphere from relieving devices cause the greatest environmental concerns to the community close to the plants. Runaway reactions in batch type reactors occur frequently due to various operational mistakes. Heat of reaction is the most frequent ignition source of runaway reactions and emergency relief.
    Additional Material: 1 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. S3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 61-67 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Risk assessments have been performed to determine the risk associated with the transportation of hazardous wastes through a city. In the course of these assessments, a number of modeling issues arose relating to transportation accident rates, the characterization of incidents, the effect of thermal radiation, the impact of exposure to toxic chemicals, and the threshold for acceptable risk. This paper discusses these issues.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. S3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 98-103 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents the design of ribbon wound pressure vessels useful for Ammonia, Urea and Methanol plants. The design is to create a thin shell of 1/5 the total wall thickness required, weld it to the end pieces, and wind 4 to 8 mm thick ribbons of 80 mm width at an angle of 15 to 30 degrees on the inner shell, using a prestress. The ribbons are welded at the ends and an even number of layers are wound cross-helically on to the shell. With more than 7000 vessels over the pressure range of 50 to 350 atmospheres in use in the various chemical industries in China over the past 30 years, their safety record has been excellent. Of particular interest has been the application of this technology in the Ammonia and Urea plants, where the design allows fabrication of these vessels at substantial reduction in cost, and early delivery, when compared to the mono wall technology.
    Additional Material: 6 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 124-126 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple analytical method is presented for estimating the hybrid minimum ignition energy (HMIE) of dust-gas mixtures, based on the assumed generality of Bartknecht's well-known test data for mixtures of propane with a series of dusts in air. Since the HMIE equation requires input data which might be unavailable, the use of conservative default methods is discussed.
    Additional Material: 1 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 138-148 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A large and potentially hazardous decrease in aldehyde autoignition temperature (AIT) occurs with increased pressure. The AIT-pressure curve determined in a 5 L stainless steel sphere was similar for propionaldehyde and butyraldehyde in air, falling from about 185°C at atmospheric pressure to 90°C at 140 psia. Reduction of oxygen concentration had little effect on propionaldehyde AIT. At 100°C and 140 psia, autoignitions accompanied by at least a doubling of pressure were observed above 4% oxygen. In the presence of a few grams of free liquid, propionaldehyde vapor ignited in air at initial conditions significantly below the AIT. The mechanism appears to involve rapid Fe-catalyzed exothermic liquid-phase oxidation leading to autoignition of the adjacent heated gas layer. An acetaldehyde vapor-air mixture in the presence of free liquid and rust exploded at room temperature when air pressure was increased to 95 psia; this result is discussed with reference to a cylinder overpressurization that occurred while making up an ostensibly sub-LFL calibration mixture with compressed air. Propionaldehyde's limiting oxygen concentration (LOC) was investigated in the near-autoignition region using the same 5L apparatus; the findings are discussed with reference to an overpressurization incident in an air-liquid partial oxidation reactor. The general results are used to illustrate the application of LOC in partial oxidation processes subject to autoignition and to discuss elements of the current ASTM draft test method for LOC, which does not address test difficulties associated with condensable and/or reactive gas systems.
    Additional Material: 16 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. F3 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 157-170 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Risk analysis in chemical process industries is an elaborate exercise involving several steps from preliminary hazard identification to development of credible accident scenarios, to preparation of strategies for prevention or control of damage.All this requires substantial inputs of time and money. In order to get an approximate yet workable assessment of risk at much lesser costs, indices have been developed which link typical findings of elaborate risk analysis to scales of risk. The scales, in turn, provide workable measures of hazards/risks/safety.In the past, indices have been reported for swift risk assessment - the noteworthy among them include Dow fire and explosion index, Mond fire, explosion and toxicity index, IFAL index, and mortality index. A few rapid ranking techniques have also been proposed.This paper presents a new system of methodologies for Hazard Identification and Ranking (HIRA). The system consists of two indices: one for fire and explosion hazards and another for the hazard due to likely release of toxic chemical. The magnitudes of these indices indicate the severity of the likely accident; in terms of the size of the impacted area.HIRA has been applied to a typical chemical process industry - a sulfolane plant - and its performance has been compared with that of the Dow's and the Mond's indices. The study reveals that HIRA is more sensitive and accurate than the other indices.
    Additional Material: 12 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 288-296 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An ammonia storage tank was built at the BASF Antwerp site in 1969 on land reclaimed from the sea. After several years of operation uneven foundation settlement, of up 2, occurred. In order to assure stability of this area for the next operation period (at least 10 years) measures were taken to ensure continued safe operation. One key measure was strain gauge monitoring at the location of maximum stress.
    Additional Material: 19 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 39-42 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Under OSHA 1910.119, all Process Safety Management (PSM) facilities are required to keep their pressure relief system design information current. This article demonstrates why a pressure relief system design verification effort must be based on an equipment list, rather than a relief device list, in order to ensure that every piece of equipment is adequately protected. The formerly common practice of simply checking the design bases of all existing relief devices is deficient is deficient since this technique does not systematically ensure that every piece of equipment is protected.The “Berwanger Method” is a step by step process for designing or analyzing a pressure relief system to meet OSHA 1910.119 Process Safety Information (PSI) and Process Hazard Analysis (PHA) mandates. The method uses a relational database which tracks the relationships between protected equipment, potential overpressure scenarios, and protective devices.The challenge facing an operating company does not end once the design basis has been “verified” - the design basis information must also be maintained and be readily accessible to avoid costly reinvention of the wheel down the road. The “Berwanger Method” also addresses these maintenance issues.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 49-60 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper reports on a comprehensive literature search and small scale experimental work on the reaction characteristics of phosphorous trichloride and water. More than 30 tests were conducted, including both closed and open test cells. The water to phosphorus trichloride molar ratio was varied from 1 to 25. When in contact, water and phosphorus trichloride will form two liquid layers with a reaction starting at the interface. The impact of variables on reaction rates including the interface surface area, layer depth, and stirring were investigated experimentally. A reaction rate model that fits all the measured data is presented. Case studies illustrating the use of this data for emergency relief systems and vent containment design are presented in reference. [1].
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  • 23
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 68-73 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two major accidents in the 80's: the summit Tunnel Fire, England and Piper Alpha disaster, an offshore platform in the North Sea; and very recently, possible explosion of the Boeing, TWA flight 800 at New York, makes it imperative that further research into the mechonisms of the ignition of flammable vapor/air mixture in contact with hot surfaces needs to be done. There have been a number of studies of ignition by hot surfaces, but in all these studies the ignition sources were wire, sphere or strip, i.e., most of them were flat surfaces. But to the authors' knowledge, other variables which affect the ignition mechanism such as irregular geometrical shapes have not been studied. The purpose of this paper is to examine how the degree of confinement (or, configuration), size and orientation, of the heated surface affects the ignition temperature of the flammable vapors. The results were obtained by experimentnal and by computational fluid dynamics.
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 272-277 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: EPA's Risk Management Program regulation, promulgated in June 1996 as 40 CFR Part 68 requires subject industries to submit Risk Management Plans by June 1999. This plan requires hazard assessment of the operations of a facility using worst case scenarios and alternative releases. EPA has provided an Off-site Consequence Analysis (OCA) guidance to help facilities in their hazard assessment.OxyChem will be significantly impacted by the RMP rule. This paper outlines OxyChem's general experience and its strategy in planning to comply with this rule. OxyChem's approach in the development of the scenarios required by the rule is described in this paper. Limitations involved in the use of EPA's look-up tables or a single modeling solution for conducting all of the OCA are discussed. A three tiered OCA approach is presented as a possible alternative.
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 26
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 1-8 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent guidelines released by the U.S. EPA define a worst-case scenario as a release under stable atmospheric conditions defined as Pasquil-Gifford stability class F. Unfortunately, very few tests at F stability have been available heretofore to provide a basis for models. Recent test data with propane releases by the German research organization TUV provide a set of 60 experiments conducted specifically to define the effects of atmospheric stability class on dispersion. Of these, 25 tests were at F stability. A comparable number were at each other stability class A through E. In addition 23 tests were at wind speeds under 1.5 m/s in stable atmospheres. This paper reports on adjustments made to our models based on these new data by reducing the originally-postulated sensitivity to stability class. In spite of considerable scatter in the TUV data, particularly between two different types of propane analyzers, the model allows us to extract information by averaging over the tests.
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  • 27
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    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 16-19 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A multi-disciplinary team developed a guideline for determining access restriction zones around vented solids handling equipment. The guideline provides a method for ensuring the discharge from a vented explosion will not cause injury to personnel. The steps in this method include: calculating the extent of external hazards from vented explosions; identifying potential areas where personnel could be exposed to a hazard; identifying ways to eliminate or reduce the hazard area; and establishing and documenting any access restrictions needed. Hazard zone calculations use the latest knowledge from research into fireball size, flame length and external pressure equations in VDI 3673. The guideline provides guidance for using this information. Options for mitigating or reducing external hazards from vented explosions are also described. As part of the project, the team audited several solids handling systems to look for potential oversights in existing restricted access areas. Some of the team's learnings from these audits are reviewed.
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  • 28
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    Process Safety Progress 17 (1998), S. 43-48 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper defines situation awareness (SA) and discusses its importance to operator-machine system safety and functioning in the context of process control activities. Specifically, identified are relationships of human detection of critical process cues converying the status of automated control systems and operator interpretation of the meaning and relevance of such information to the potential for negative incidents in chemical processing. Beyond individual operator SA in interacting with control systems, intra- and inter- work team SA are discussed for supporting individual attainment of process control responsibilities. Factors critical to team SA are discussed. “Road blocks” to team SA are also analytically examined. Lastly, methods for assessing individual and team SA are reviewed and vehicles for relating outcomes of these methods to changes in process control operator and team behavior to improve human-machine system safety and performance are relayed.
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  • 29
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 30
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    Process Safety Progress 17 (1998), S. 74-81 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of the ingition behavior of dust-air mixtures due to electrical sparks (MIE, Minimum Ignition Energy) and hot surfaces (MIT, Minimum Ignition Temperature) is important for risk assessments in chemical production plants. The ignition behavior determines the extent and hence the cost of preventive protection measures.This paper describes the use of the minimum ignition energy and minimum ignition temperature as very important safety indexes in practice.Based on the latest results from large scale experiments on pneumatic filling of silos with polymeric materials and new results of full scale filling tests using Flexible Intermediate Bulk Containers (FIBC) manufactured from a variety of materials, guidance can be given to ensure safe operation in different situations such as filling, emptying operations, type of powder handled.The aim of this paper is to assist people dealing with product. It reflects the present state of the art and current knowledge of the assessment and measures associated with powder handling.
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  • 31
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    Process Safety Progress 17 (1998), S. 104-106 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In mid-1997, an Advanced Process Control (APC) scheme was implemented at a resins manufacturing complex with the goal of minimizing flare fuel gas usage while maintaining sufficient energy (BTU/SCF flare gas) to be in environmental regulatory compliance. Prior to APC implementation, the flare system was manually controlled by plant operators with minor attention paid to the minimization of fuel gas usage. Since implementation, APC has saved the plant thousands of dollars in fuel gas costs and reduced unnecessary combusted fuel gas emissions.Hazard analysis techniques were used in the development of the control scheme. An overview of the APC used, the economic evaluation, and the hazard analysis techniques used in the project are presented here.
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  • 32
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    Process Safety Progress 17 (1998), S. 107-123 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the risk assessment parlance, especially with reference to chemical process industries, the term “domino effect” is used to denote “chain of accidents,” or situations when a fire/explosion/missile/toxic load generated by an accident in one unit in an industry causes secondary and higher order accidents in other units. The multi-accident catastrophe which occurred in a refinery at Vishakhapatnam, India, on September 14, 1997, claiming 60 lives and causing damages to property worth over Rs 600 million, is the most recent example of the damage potential of domino effect.But, even as the domino effect has been documented since 1947, very little attention has been paid towards modeling this phenomena. In this paper we have provided a conceptual framework based on sets of appropriate models to forecast domino effects, and assess their likely magnitudes and adverse impacts, while conducting risk assessment in a chemical process industry. The utilizability of the framework has been illustrated with a case study.
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  • 33
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 34
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    Process Safety Progress 17 (1998), S. 149-154 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article deals with fire protection for water miscible flammable liquids stored in plastic containers packaged in boxes located on pallets. A series of fire tests was conducted with palletized rack storage arrangements using in-rack sprinkler protection at various levels. The intent of the paper is to present data from this test series for these types of commodities. The paper will identify various existing water miscible flammable liquid products stored in this fashion and provide background information for protecting this type of storage as it relates to NFPA 30 Flammable and Combustible Liquids Code. The test data indicates that further research work is needed in the area of plastic containers for use with the storage of combustible and flammable liquids. Included in the paper are discussions concerning possible protection strategies and suggestions for future research which would benefit those involved in risk management of this type of commodity.
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  • 35
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    Process Safety Progress 17 (1998), S. 176-183 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The safest method to prevent fires and explosions of flammable mixtures in the first place. This method requires detailed knowledge of the flammability region as a function of the fuel, oxygen, and nitrogen concentrations. A triangular flammability diagram is the most useful tool to display the flammability region, and to determine if a flammable mixture is present during plant operations.This paper describes how to draw and use a flammability diagram. A procedure to estimate the flammability region using the available and sometimes limited data is discussed. The paper also shows how to use the flammability diagram with plant operations involving inerting and purging, and from bringing vessels into and out of service. A compilation of flammability diagrams for 30 materials, based on previously published data is provided.An automated apparatus for acquiring data for a flammability diagram is described. The apparatus consists of a 20-L sphere with an automated gas mixing system, a fuse-wire ignition system, and a high speed pressure measurement and data acquisition system. Data derived from the apparatus includes flammability limits, maximum pressure during combustion, and the maximum pressure rate. The effect of fuse-wire ignitor dynamics on the results is studied. A flammability diagram for methane drawn from data obtained from the apparatus, is presented.
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  • 36
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    Process Safety Progress 17 (1998), S. 209-212 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: HFC-227ea (CF3CHFCF3;1, 1, 1, 2, 3, 3, 3-heptafluoropropane) is an effective replacement for Halon 1301 in fire suppression systems, providing rapid extinguishment of flames through a combination of physical and chemical mechanisms. The vast majority of applications for HFC-227ea involve the protection of Class A hazards, which are characterized by low fuel loadings and low energy output, with fire sizes often in the range of 5-10 kW. Mid- and large-scale testing has demonstrated that HFC-227ea, at its minimum design concentration of 7.0% v/v, is effective at extinguishing fires typical of those expected to occur in electronic data processing (EDP) facilities, telecommunication facilities and anechoic chambers. The levels of HF produced following extinguishment of typical Class a fires with HFC-227ea were well below the estimated mammalian LC50 and the human Dangerous Toxic Load (DTL), and do not appear to present a threat to electronic equipment.
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  • 37
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    Process Safety Progress 17 (1998), S. 219-224 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sandia National Laboratories (Sandia) has refined a process for developing inherently safer system designs based on methods used by Sandia to design detonation safety into nuclear weapons. The process was created when Sandia realized that standard engineering practices did not provide the level of safety assurance necessary for nuclear weapon operations, with their potential for catastrophic accidents. A systematic approach, which relies on mutually supportive design principles integrated through fundamental physical principles, was developed to ensure a predictably safe system response under a variety of operational and accident-based stesses. Robust, safe system designs result from this thematic approach to safety, minimizing the number of safety critical features. This safety assurance process has two profound benefits: the process avoids the need to understand or limit the ultimate intensity of off-normal environments and it avoids the requirement to analyze and test a large array of accident environment scenarios (e.g., directional threats, sequencing of environments, time races, etc) to demonstrate conformance to all safety requirements.
    Additional Material: 3 Ill.
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  • 38
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    Process Safety Progress 17 (1998) 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 39
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    Process Safety Progress 17 (1998), S. 233-237 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method is described to enhance the management of process safety risks such that the number and type of safety systems protecting against any hazard are consistently predicated upon risk. Further, that such an assignment of safety systems can be made consistent throughout an organization. This consistency is gained through standardization of qualitative risk ranking and by setting company guidelines.
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  • 40
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    Process Safety Progress 17 (1998), S. 243-258 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Research was carried out to develop improved protection guidelines for silane handling systems through enhanced understanding of the behavior of releases of this pyrophoric gas. The approach involved addressing three aspects of the problem: the prompt ignition behavior of silane; the reactivity characteristics of quiescent silane/air mixtures; and the rates of reaction of silane leaked into enclosures with and without explosion venting, in the presence of ventilation air flow. A first conclusion, reached from tests in a ventilated cabinet, was that, contrary to prevailing belief, the ventilation flow has no measurable effect on the prompt ignition of the release. From experiments in a 5.1-liter (311-in.3) sphere it was found that silane/air mixtures of concentrations between 1.4 and 4.1% (by volume) are explosive but stable. In this case, piloted ignition tests yielded laminar burning velocities up to 5 m/s (1000 ft/min). Mixtures between 4.5 and 38% (the maximum reached in the tests) were found to be metastable, and would undergo spontaneous ignition after a delay ranging from 15 to 120 seconds, with the shorter values corresponding to higher silane concentrations. Experiments were also performed in a 0.645-m3 (22.8-ft3) vessel both with and without explosion venting, to measure the rates of energy release associated with impulsively-started silane leaks from 1/8 and 1/4-in. (3.2 and 6.4-mm) lines. A method for the prediction of the venting requirements of partial-volume deflagrations (PVD) was evolved into a tool to quantify the pressure rise from ignition of silane leaks in enclosures. These results represent a significant step toward updating existing design recommendations which prescribe ventilation requirements that are based on outdated and, in some instances, misinterpreted data.
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  • 41
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    Process Safety Progress 17 (1998), S. 278-287 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas explosion simulators are often used as tools in process plant design. This article presents some properties of gas explosions found using the EXSIM simulation software on three offshore modules with a total of nearly 10,000 simulations. The selected results are chosen for their supposed applicability to structural design in the process industries.Generalized data are presented for the effect of gas cloud size, explosion impulse vs. explosion pressure, pressure and impulse vs. duration, the probability of a “short” explosion, loading rate, pressure-time “shape” function, and the effect of introducing louvers.
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  • 42
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    Process Safety Progress 17 (1998), S. 9-15 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design and deflagration pressure relief vents is based on correlations developed for various types of combustible materials and for enclosures of different strengths. The primary guideline for deflagration vent design in the US is NFPA 68 Guide for Venting of Deflagrations [5]. That document gives guidance for the design of vents for enclosures containing flammable gases, specifically hydrogen, coke oven gas, propane, and methane. Application of the guide to other gases is achieved using the KG value. Values of KG are published for a relatively small number of gases, as seen in Table D-1 of NFPA 68. This work present KG data on several additional gases obtained in a laboratory scale test vessel along with analysis of the results with respect to published values of fundamental burning velocity.
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  • 43
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    Process Safety Progress 17 (1998), S. 23-31 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In May 1996, the Flammable and Combustible Liquids Code Committee of the National Fire Protection Association (NFPA) proposed for adoption by the Association a new edition of NFPA 30, Flammable and Combustible Liquids Code. This new edition was the culmination of two and one-half years' work by the Committee and included one of the most significant changes to that document in some twenty years: the incorporation of mandatory fire protection criteria for warehouses and other inside areas that store flammable and combustible liquids in containers and portable tanks.
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  • 44
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    Process Safety Progress 17 (1998), S. 32-38 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes the development of a risk ranked Inspection Recommendation procedure that is used by one of Exxon's chemical plants to prioritize repairs that have been identified during equipment inspection.As part of the Company's Safety Management Practices initiative in the late 1980's a procedure was put into place to ensure that an Inspector's repair recommendations were properly addressed by the organization. The initial procedures were successful at “systematizing” the documentation and stewardship-to-completion of the Inspector's recommendation, however, there were complications with the original process: (1)The Inspector made a simple High, Medium or Low assessment of the priority/criticality of the recommendation. Frequently, this resulted in disagreements with Operations about the true priority of the recommendation.(2)If there was agreement on the priority of the recommendation, there was still disagreement on the relative rank within the priority-which high priority was the highest priority?(3)With limited funds to spend on repairs, it was (and is) important to make sure that the money was being spent on the highest risk items that had the greatest risk reduction/cost benefit ratio.To address these concerns, the procedure was modified to incorporate a risk assessment of the recommendation by both the Inspector and Operations. In the new procedure, the Inspector describes the deficiency that he/she finds and assesses the probability of failure within a certain time-frame. Operations must assess the consequences, from an environmental, safety and economics standpoint, were the failure to occur. These assessments are combined in the typical risk equation (risk = probability × consequences) to arrive at a severity index which serves to rank the recommendation relative to the other recommendations. Because Operations participates in the assessment there is very little disagreement about the priority of the recommendation. The severity index puts the recommendations in order so it is quite clear which are the highest priority recommendations. This process has helped to focus the entire organization on those deficiencies that represent the greatest risk with the result that less time and money is spent correcting items that have a low risk/cost benefit ratio, allowing these savings to be used to reduce the higher risks in the plant.
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  • 45
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    Process Safety Progress 17 (1998), S. 200-208 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 14 Ill.
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  • 46
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    Process Safety Progress 17 (1998), S. 213-218 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: On October 31, 1987 a crane lifting a heat exchanger convection section failed and severed a 4″ loading line and a 2″ pressure relief line to an HF alkylation reactor settler drum at a petroleum refinery in Texas City, Texas. Vapors were emitted under pressure for about two hours and the vessel was plugged and drained aproximately 44 hours later. A plume from this accidental release passed through residential areas, damaging some vegetation (brown lawns), and spawning a class action law suit. An extensive analysis was conducted to determine the total inventory loss and to model the blowdown process and the concentrations of HF in the plume. Since the discharge rate was decreasing with time, a peak concentration of HF in the emitted vapors occurred just before the water spray mitigation system became fully operative. Consequently, the mitigation efforts were more effective late in the response when concentrations were already low. The predicted plume concentrations are consistent with observed vegetation damage effects, with concentrations below Emergency Response Planning Guideline Level 3 past 3/4 mile from the source. These results support a policy of sheltering in place during such an event.
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  • 47
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fifty-five gallon steel drum of a liquid organic peroxide pressurized and ruptured in the mix room of a manufacturing plant. The head of the drum blew off and the ejected material ignited. The resulting fire was extinguished by the building sprinkler system and operating personnel. Although there were no injuries, the fire caused significant damage in the mix room. The investigation of this incident, its likely cause, and the corrective actions will be discussed.
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  • 48
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    Process Safety Progress 17 (1998), S. 238-242 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Brazoria County Petrochemical Council, 13 companies that are working together to enhance relations between industry and the community, united in a joint effort at complying with the EPA's Risk Management Program. One of the significant issues the group had to address was the need to develop meaningful hazard assessment for presentation to the public. The EPA's “Table Look-Up Approach” found in the Offsite Consequence Analysis Guidance document is certainly a good tool; however, the built-in conservatism results in over-estimates of potential hazard areas. Much more meaningful results are shown to be obtained using one of the hazard release models.The value of using a credible scenario with realistic meteorological data is demonstrated through the consistently smaller areas predicted by the PHAST Model for planning purposes. Realistic scenarios/failure modes and realistic model parameters are important so that the risk to the public is not overstated. Proprietary models such as PHAST are invaluable in providing more meaningful consequences for planning purposes.
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  • 49
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    Process Safety Progress 17 (1998), S. 263-271 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some of the hazards encountered by process plant operators involve the operation of in-line valves to control, start, and to stop flow. Torque required to operate valves may vary according to valve wheel size, in-line pressure, and valve flange position (open/closed). This study determined how valve wheel size, in-line pressure and valve position (open/closed) affect torque required to actuate a valve. Data were gathered with each combination of size, pressure and position for 336 valves in an operating petrochemical process facility. The results indicate that the main effects of valve wheel size, the in-line pressure, and open/closed valve position significantly affect operational torque requirements. In addition, the interaction between position and pressure was significant for operational torque. The implication of these results is that operators are exposed to operational torque requirements that exceed maximum acceptable capabilities that have been determined in previous studies.
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  • 50
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    Process Safety Progress 17 (1998), S. 83-85 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Safety, health and loss prevention are major areas of interst for the American Institute of Chemical Engineers (AIChE). There has been an evolution of these concerns over the years in the Institute just as it has in industry. This article chronicles this evolution.
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  • 51
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    Polymer Engineering and Science 26 (1986), S. 9-14 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyolefins functionalized with diethylmaleate were mixed with poly(vinylchloride) (PVC) in different compositions. Intermolecular interactions involving the carbonyl groups of the side chains of the functionalized polyolefins and methine hydrogens of PVC were investigated by means of infrared spectroscopy. The major flexibility of the ester groups attached to the backbone chains, with respect to polyesters, seems to increase the capability of such groups to interact with groups of more polar polymers, thus allowing prediction of easier miscibility, which however also depends on the starting polyolefin structure and function-alization degree.
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  • 52
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    Polymer Engineering and Science 26 (1986), S. 15-27 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Non-aqueous dispersions of poly(vinyl acetate) stabilized by a surface layer of poly(2-ethylhexyl methacrylate) (PEHMA) were prepared. We modified the recipe for particle synthesis, using as a stabilizer a copolymer of EHMA containing a small amount of either phenanthrene (Phe) or pyrene (Py) groups. These fluorescent labels permit us to assess different aspects of stabilizer chain morphology and dynamics. In the particles labeled with Phe groups, the ability of oxygen to quench Phe fluorescence is used as a monitor of O2 sorption at the stabilizer-particle interface. In these experiments, information about the location of the labels and the PEHMA polymer is obtained. In the particles labeled with Py, pyrene self-quenching and excimer formation serves as a sensor of conformational and mobility changes in the PEHMA polymer upon anchoring in the particle.
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  • 53
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The phase morphology and polymer chain orientation in polyethylene-polycarbonte blends is investigated. A blend with a dispersed polyethylene phase was found to exhibit phase growth under quiescent conditions. Addition of a styrene-(ethylene/butene) block copolymer controls the phase morphology and prevents phase growth. Melt spun tapes and tubular film have been prepared from polyethylene-polycarbonate blends. Orientation of the crystallo-graphic axes of the polyethylene and the chain axis of the polycarbonate were determined by infrared dichroism. The addition of polycarbonate to polyethylene is found to decrease chain orientation at the same drawdown stress.
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  • 54
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    Polymer Engineering and Science 26 (1986), S. 1-1 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 55
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    Polymer Engineering and Science 26 (1986), S. 3-8 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A systematic study of static and kinetic phase behavior of deuterated polystyrene/poly(vinylmethylether) blends is presented in this paper. The static properties are studied by the small angle neutron scattering techniques and the kinetics of phase decomposition are studied by the temperature jump light scattering; technique. This procedure provides detailed information about phase behavior with regard to both thermodynamics and kinetics.
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  • 56
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    Polymer Engineering and Science 26 (1986), S. 34-44 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Commercial high density polyethylene and polyamide-6 (PA) resins were melt blended in the Brabender Plasticorder twin-screw extruder. The blends containing zero to 30 wt percent of polyamide-6 were examined in dynamic and steady state shear at 150, 200, and 250°C. The Theological test results are discussed in terms of morphology of the samples as observed under scanning electron microscope. Microscopy of the extrudates has shown a temperature dependent movement of the polyamide in the capillary during the extrusion and that fibrillation of the PA phase in the extensional field occurred at all temperatures.
    Additional Material: 18 Ill.
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  • 57
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    Polymer Engineering and Science 26 (1986), S. 103-110 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theoretical model proposed for simulation of the injection molding of partially crystalline thermoplastics can predict fill time, velocity, temperature and pressure distributions, the distribution of shear and normal stresses, crystallinity, amorphous birefringence, and tensile moduli. In this paper, experimental data will be compared to the predictions of the model.
    Additional Material: 22 Ill.
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  • 58
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    Polymer Engineering and Science 26 (1986), S. 28-33 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rheological data have been collected both in shear and non-isothermal elongational flow on three different types of blends, made from one low density polyethylene sample and three linear low density polyethylene samples.In addition to the flow curves, data are presented on the extrudate-swell phenomenon, on the instability arising in capillary flow and on the tensile behavior in the molten state.
    Additional Material: 15 Ill.
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  • 59
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    Polymer Engineering and Science 26 (1986), S. 74-81 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The impact fracture of nominally identical high impact polystyrene resins having different and well-characterized rubber particle size distributions is discussed. A numerical model for craze termination is presented and its predictions are compared with experimental data. An alternative explanation for the observed effect of particle size on fracture energy is considered.
    Additional Material: 14 Ill.
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  • 60
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    Polymer Engineering and Science 26 (1986), S. 63-73 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Morphology and mechanical properties of (amine terminated butadiene acrylonitrile rubber/diglycidyl ether of bis-phenol-A epoxy resin) blends of different compositions, cured in wide range of temperatures, are described. Curing at low temperature promoted formation of homogeneous materials with poor fracture resistance. On the contrary, at high temperature tough heterogeneous blends were obtained. Such blends showed phase inversion above 20 percent of rubber. The volume fraction of precipitated phase, determined on SEM micrographs, was higher than the amount of added rubber. A fracture mechanism to account for this is proposed. Extensive voiding and interface damage were observed in the low temperature cured materials. Such phenomena did not contribute to the fracture energy.
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  • 61
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    Polymer Engineering and Science 26 (1986), S. 111-115 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The key to successfully implementing polymer blends in end-use applications includes an understanding of performance requirements and the physical property balance of the blend, as well as the provision of financial incentive to the fabricator, The economic gain is calculated for two cases where blends were introduced to displace another material: a blend which gives higher productivity for blown film applications and a blend which allows for increased flow and a gage reduction for an injection molding application. As the resin cost usually accounts for more than seventy percent of the final product cost, the resin or blend cost affects the economic gain (if any) from the fabricator's point of view. Therefore, successful commercial implementation of a new resin or blend depends on its relative cost and benefit to other commercially available materials.
    Additional Material: 3 Ill.
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  • 62
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    Polymer Engineering and Science 26 (1986), S. 1405-1409 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In recent years there has been increasing recognition of the importance of melt elasticity in polymer processing. A new instrument has been developed that determines the elastic properties of polymers in the melt state by measuring both the stress relaxation and strain recovery characteristics as a function of applied rate of strain, temperature, and magnitude of applied strain. Data on several different polymers will be presented together with examples of the significance of melt elasticity in such processing operations as thermoforming, blow molding, and film forming. A material parameter that is very important in the processing of polymers such as polystyrene and poly(methylmethacrylate) is the transition above the glass transition, Tg, referred to as the liquid-liquid transition, TII. At this transition there is an abrupt change in the elasticity of the melt. Processing above or below this transition produces products with very different end use properties.
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  • 63
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The interfacial tensions of immiscible binary blends of poly(dimethyl siloxane) (PDMS) and polybutadiene (PBD) have been determined as a function of molecular weight and temperature. The technique employed for these measurements takes advantage of recent advances in the determination and analysis of pendant fluid drop profiles. The experimental data are compared to the predictions of square gradient theories and theories based on the diffusion equation approach as developed by Helfand and co-workers. Qualitative agreement is obtained with both types of theory when the Flory-Huggins interaction parameter is taken to be comprised of two terms: a temperature independent term of entropic origin; and an enthalpic term that is inversely dependent upon the temperature.
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  • 64
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    Polymer Engineering and Science 26 (1986), S. 1429-1433 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interrelationships between reaction conditions and material properties of thermosetting and high Tg polymers are discussed from the point of view of a generalized time-temperature-transformation (TTT) diagram.
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  • 65
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    Polymer Engineering and Science 26 (1986), S. 1451-1456 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The glass transition temperatures (Tg) and dynamic mechanical properties of random copolymers of styrene-4-vinylpyridine quaternized with iodoalkanes are presented for vinylpyridine contents up to ten percent and pendant alkyl chains up to ten carbons in length. Two linear relationships, between ion content and glass transition temperature and between pendant alkyl chain length and the Tg, are observed. An equation is presented that can be used to predict the Tg for such copolymers based on their ion contents and alkyl chain lengths.
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  • 66
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 67
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    Polymer Engineering and Science 26 (1986), S. 1469-1477 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyetheretherketone (PEEK) is a relatively new high temperature engineering thermoplastic. The stability of neat and fiberglass reinforced PEEK towards air, KClO4, and TiH1.65/KClO4 blend was studied by the surface sensitive technique of X-ray photoelectron spectroscopy (XPS) and bulk technique of thermogravimetric (TG) analysis. Both of these examinations revealed no oxidation in the presence of air or KClO4 at temperatures of 60 or 120°C. In addition, no reduction of PEEK was observed in the presence of a reducing agent such as TiH1.65. The TG results also showed no air oxidation between 120 and 500°C.
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  • 68
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    Polymer Engineering and Science 26 (1986), S. 1478-1482 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The miscibility of the polycarbonate of bisphenol A with the polyhydroxyether of bisphenol A was analyzed using differential scanning calorimetry and the, results are compared with the torque data obtained using a Brabender Plasticorder. The possibility of interchange reactions was analyzed by means of the observation of the melt-viscosity variation versus processing time in the mixer-bowl. These reactions form graft-copolymers that develop into crosslinked copolymers at higher residence times. It was also shown that the speed of these reactions depends on the processing temperature. The variation produced on the glass-transition temperature because of branching was also analyzed.
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  • 69
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    Polymer Engineering and Science 26 (1986), S. 1552-1562 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A general-purpose finite element program has been used to simulate the flow of nonshear-thinning, highly elastic polymer solutions (Boger fluids). In particular, the creeping flow through an abrupt 4:1 circular and planar contraction is studied, as well as the flow at the exit of a capillary die for the determination of extrudate swell. Experimentally measured normal stress and viscosity data are included in a simple rheological model, based on the viscometric simplification of the CEF constitutive equation. Vortex size and intensity in the die entry and extrudate swell at the die exit increase rapidly, with elasticity level, in general agreement with experimental findings. It is shown that despite the limitations of the model, the viscometric approximation can be used to study the effect of normal stresses in cases where a main flow direction can unambiguously be defined. In die exit Flows, it can also provide an upper limit for the determination of extrudate swell, while Tanner's theory of elastic recovery provides the lower limit.
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  • 70
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    Polymer Engineering and Science 26 (1986), S. 1533-1542 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The transport property of chloroform in undeformed and stress-whitened polypropylenes was studied. The rate of penetration of liquid chloroform in whitened samples prepared by uniaxial stretching was slower than that of the undeformed material. In the whitened region, the process appeared to be Fickian diffusion, while in the undeformed material, it was a combination of Fickian and Case-II. The diffusivity (at 50°C) in the whitened region increased about 8 times as the strain rate of stretching decreased from 0.67 to 0.033/min. The temperature dependence of diffusivity (ε = 0.67/min) showed an activation energy of 10.16 Kcal/mole. The whitening effect was greatly reduced as chloroform was absorbed; the final residual whitening after desorption increased with the rate of stretching as determined by transmission densitometry. For the undeformed polypropylene, Case-II type of matrix relaxation contributed significantly to the total flux. The transport process was relaxation controlled at the surface: it gradually changed to Fickian diffusion behavior toward the middle plane. The flux contribution of relaxation across the thickness increased with the sorption time, and that of diffusion decreased. These observations seem to indicate that cold drawing impeded the deformation by swelling stress from occurring at the penetration front.
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  • 71
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    Polymer Engineering and Science 26 (1986), S. 468-478 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the application of plastic pipes for fluid transport and for the protection of underground electrical cables, it is desirable to improve mechanical properties, particularly in the hoop direction. The use of orientable reinforcing particles such as chopped glass fibers could make possible such an improvement if the orientation of the fibers could be controlled. While conventional pipe extrusion dies tend to promote axial fiber orientation, the use of an expanding channel die has been proposed to produce a preferential hoop orientation of fibers. In this paper, a theoretical model of the flow of a fiber suspension through an expanding channel die that predicts the fiber orientation distribution at the die exit is described. The effects of Theological properties and die geometry on the final fiber orientation distribution are predicted. The results of an experimental study of fiber orientation in pipe extruded using an expanding channel die are shown to be in agreement with the theoretical predictions.
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  • 72
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    Polymer Engineering and Science 26 (1986), S. 534-542 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of pressure on the densification of amorphous polymers in the Injection-molding process is examined. Density distributions in molded polystyrene slabs were measured for several well-defined molding histories. In all cases the density of the molded part was spatially inhomogeneous, and its distribution in the slab was closely related to the pressure and temperature histories that prevailed in the molding cavity during the process cycle. The density profile in the gapwise direction followed a characteristic “parabolic” pattern with a minimum at the midplane of the slab. A simple phenomenological model, based on the pressure-induced densification effect, was constructed to explain the observed density profiles, and close agreement with experimental data was found. Annealing of the molded article at a high temperature (〈Tg) caused the density to decrease overall and become more uniform across the part. This is generally consistent with volume-recovery data for the densified material, which were generated independently in a controlled pressure-densification experiment.
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  • 73
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    Polymer Engineering and Science 26 (1986), S. 543-553 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A systematic design of the classical “coat hanger” die is proposed and tested experimentally. The objectives of the design are 1. distribution of the polymer over the width of the die before it reaches the final lip section for thickness adjustment, 2. invariance of distribution to flow rate, 3. invariance to changes in polymer viscosity, and 4. uniform average residence time. The die design is based on a flow model which assumes power-law viscosity, steady shear flow In each cross-section, uniform temperature, and separation of the flows into a manifold component and a component in a slit section of uniform height. The design corrects for an oversimplification of the pressure gradient that was applied in previous studies; and it differs from previous designs by suggesting a rectangular cross-section for the manifold. Applications to side-fed dies for extrusion blow molding and to a sheet extrusion die achieved uniform distribution and did not require any additional flow corrections (such as choker bars or flexible lips). With the new design, the lip region of the die can freely be used for thickness control, fine tuning, or further shaping of the extrudate.
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  • 74
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    Polymer Engineering and Science 26 (1986), S. 662-672 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rheological behavior of sulfonated polyisobutylene based elastomeric ionomers has been studied. The effects of molecular architecture, type of cation, and addition of excess neutralization agent were investigated. The effect of temperature was studied to a limited extent. In a specific case, the influence of an ionic plasticizer, zinc stearate was also examined. It was found that in these telechelic ionomers where the ionic groups are located exclusively at the chain ends, significant Ionic interactions may persist even at 180°C. The zinc-neutralized ionomers had the lowest viscosity as compared to the corresponding potassium- or calcium-neutralized ionomers. The covalent character of zinc is believed responsible for this behavior. Other factors being constant, the triarm based ionomers are more viscous than the monofunctional ionomers. A mixture of monofunctional ionomers with the triarm, species is a model for dangling chain ends, and results in a slight lowering of the viscosity under the conditions studied. Zinc stearate acts as an ionic plasticizer. Upon the addition of 15 percent by weight of zinc-stearate to the ionomer, the low shear rate viscosity drops by several orders of magnitude and renders the ionomer thermally processable at moderate temperatures.
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  • 75
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    Polymer Engineering and Science 26 (1986), S. 673-681 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental investigation was conducted into elucidating the mechanism of foam devolatilization. For the investigation, we have constructed two separate apparatuses of Plexiglas - one simulating the partially filled flow channel in a single-screw devolatilizer, and the other simulating the partially filled, closed-chamber (often referred to as the “C-chamber),” in a twin-screw devolatilizer. The test fluids employed were aqueous solutions of polyacrylamide having various concentrations. During the preparation of the test fluids, we controlled the amount of air entrapped in the liquid phase by varying the level of vacuum applied. The entrapped air stayed as fine gas bubbles dispersed in the polymer solution, and mixtures of the polymer solution and air bubbles were subjected to devolatilization experiments. In the use of a single-screw devolatilizer, we have observed that: 1. The streamlines show circulatory flow patterns forming a singular point at a position slightly below the free surface, where small gas bubbles are trapped initially and become stationary, and 2. The small gas bubbles trapped at the stationary position coalesce later to form large gas bubbles, which then move slowly toward the free surface and are removed under vacuum from the system. In the use of twin-screw devolatilizers, we have found that the degree of fill, the rotational direction of the screws, and the degree of intermeshing, (i. e., partially or fully intermeshing) greatly influence the amount of free surface available for the removal of volatiles, as well as the flow patterns in the liquid pool, and thus the devolatilization efficiency.
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  • 76
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    Polymer Engineering and Science 26 (1986), S. 690-694 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Drawing of a semicrystalline polymer causes a molecular transformation from a spherulitic-to-fibrillar morphology. Shrinkage, which is a characteristic property of polymeric fibers, reverses, to a large extent, the extension that takes place during the deformational process of drawing. This paper focuses on the shrinkage behavior of various drawn semicrystalline polymers and the results are used as further evidence for the feasibility of a phase-transition model whose mechanism can be generally termed “strain-induced recrystallization.”
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  • 77
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    Polymer Engineering and Science 26 (1986), S. 682-689 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theoretical study of the one-directional coextrusion flow of two molten polymers between parallel plates has been carried out using a non-isothermal power-law model. A numerical method has been used to solve simultaneously the momentum and energy balance equations, in order to obtain the evolutions of the interface position, the pressure gradient, and the temperature profiles all along the flow. The theoretical results are in good agreement with experimental values measured on an industrial coextrusion line.
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  • 78
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    Polymer Engineering and Science 26 (1986), S. 695-700 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The National Center for Small-Angle Scattering Research (NCSASR) is a user dedicated national facility at the Oak Ridge National Laboratory. It is sponsored by the National Science Foundation under an interagency agreement with the Department of Energy. The facilities of the Center include the NSF funded. 30-m small-angle neutron scattering (SANS) instrument at the High Flux Isotope Reactor, as well as part-time use of four other small-angle x-ray and SANS instruments. One of the most active areas of SANS research has been polymer science and over half the proposals received by the Center have been in this area. Approximately 20 percent of the beam time has been allocated to users in the chemical industry for the study of polymer structure, and this paper reviews some highlights of this work in the areas of chain configuration in bulk polymers and solutions, the structure of blends and networks and investigations of core-shell latexes. In addition some of the first time-dependent experiments performed on the 30-m facility are described.
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  • 79
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    Polymer Engineering and Science 26 (1986), S. 717-724 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model describing the expansion of a polyurethane (PU) foam in a closed mold is developed. An energy balance is stated, together with constitutive equations for the vaporization rate of the foaming agent and the polymerization kinetics. A numerical solution is obtained for an experimentally-characterized PU formulation. It is shown that in order to avoid premature gelling or undesirable density distributions, the wall temperature must be close to the initial one. The relative fraction of skin in the foam may be increased by decreasing the part thickness or by adding less catalyst or more blowing agent to the formulation. Factors affecting cream, rise, and process times are discussed.
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    Polymer Engineering and Science 26 (1986), S. 725-729 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The incremental response ΔG(t) obtained by superposing a deformation, Δγ, on a large deformation, γ1, has been determined in step shear experiments for a polyisobutylene solution and for a poly(methylmethacrylate) glass in torsion. For both systems ΔG(t) at γ1 was found to be smaller than the linear viscoelastic modulus, G(t), at zero prestrain. ΔG(t) was found to increase with increasing time, te, after imposition of the large deformation. It was also observed that the “apparent relaxation spectrum” associated with ΔG(t) narrows and shifts to shorter times when compared to the spectrum associated with the linear viscoelastic modulus, ΔG(t). The results for the solution art-well described by the nonlinear constitutive equation of the BKZ elastic fluid theory. It is found that ΔG(t) for the glass falls between the behavior predicted by the BKZ theory and the linear viscoelastic behavior.
    Additional Material: 7 Ill.
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  • 81
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The extent of molecular demixing of poly[cross-(ethyl acrylate)]-inter-poly[cross-(methyl methacrylate)] interpenetrating polymer networks (PEA/PMMA IPNs), of mid-range composition was investigated by decrosslinking and/or annealing using dynamic mechanical spectroscopy. A single broad transition characteristic of extensive but incomplete molecular mixing was observed for the PEA/PMMA IPN. The presence of crosslinking in both phases of an IPN enhances the mutual miscibility of the polymers. Through the use of a labile crosslinker, acrylic acid anhydride (AAA), polymer networks may be decross-linked, allowing the chains to separate and form two distinct phases. Annealing further sharpens the transitions, and phase separation becomes most pronounced when decrosslinking is followed by annealing.
    Additional Material: 8 Ill.
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  • 82
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 736-745 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An extensive experimental study of the effect of processing and resin variables on the light transmission of polypropylene tubular blown film is reported. The resin variables investigated include melt flow rate (average molecular weight), molecular weight distribution, and the addition of a nucleating agent. Processing variables studied include blow-up and draw down ratios, and frost line height (cooling rate). Increasing the draw down and blowup ratios and decreasing the frost line height generally lead to increased light transmission. Decreasing the resin melt flow rate, narrowing the molecular weight distribution, and the addition of a nucleating agent also improve light transmission. The overall light transmission properties of the films are dominated by their surface roughness characteristics, while the internal morphology of the films plays a secondary role. The changes in light transmission of the films in response to changes in processing or resin variables were traced to their effect on the surface texture and internal morphology.
    Additional Material: 13 Ill.
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  • 83
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 760-767 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The use of the J method to characterize fracture is described, and it is noted that smaller specimens may be used to obtain plane strain values than in conventional linear elastic fracture mechanics (LEFM) tests. Various methods of computing J are described, and the extrapolations necessary to define crack initiation are discussed. The various schemes and size criteria are then explored for a polypropylene copolymer, and it is found that the recommended ASTM procedure using energy works well. The method is then used to characterize several toughened polymers, and some discussion of the slope of the resistance curve is given.
    Additional Material: 12 Ill.
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  • 84
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 746-759 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The generally accepted kinetic mechanism for free radical copolymerization was simplified by various assumptions and restrictions to give several realistic and easily evaluated models for the simulation of industrial molding. Six assumptions, including conversion-dependent rate coefficients and constant comonomer concentration ratios, were used to obtain a simplified model. Special cases of this simplified model were obtained by the following additional constraints: (1) Restriction C, consecutive inhibition and radical generation reactions; (2) Restriction I, constant initiator decomposition rate; (3) Restriction Z, zero termination rate for free radicals; and (4) Restriction K or P, all rate coefficients independent of conversion or only polymerization rate coefficient dependent on conversion. For various combinations of these restrictions, the time and concentration variables in the simplified model are separated and solved; the separate solutions are then combined in various ways to give models capable of predicting a wide variety of behavior. Many of these models have analytical solutions that greatly facilitate the evaluation of rate constants. Models based on restrictions KCI, PCI, and PCZ are shown to give good agreement with isothermal DSC data plotted as reaction rate versus time and, in a more sensitive test, as reaction rate divided by monomer concentration versus fractional conversion. Because of their predictive ability and ease of evaluating constants. Models PCI and PCZ are recommended for simulating industrial processing; they are particularly well suited for simulating compression molding of sheet molding compound.
    Additional Material: 5 Ill.
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  • 85
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 86
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 768-775 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The strength and durability in wet environment of aluminum/epoxy/aluminum joints are investigated as a function of structural changes of γ aminopropyltriethoxy silane (γ-APS) primer at the interface. Both dry and wet strengths exhibit strong dependencies on both the thickness and the extent of drying of γ-APS prior to joint formation. Generally, dry strength decreases with increasing thickness of γ-APS primer, and increases with dehydration of γ-APS at any given thickness. Strength retention of the joints after exposure to water at 55°C also improves dramatically when the adsorbed γ-APS is extensively dried. These results are analogous to earlier observations with α-Al2O3/polyethylene joint system. In aluminum joints, porous oxide substrate facilitates the mechanical interlocking mechanism, and its interplay with both the thickness and the extent of cure of γ-APS is analyzed by characterizing the fractured surfaces using scanning electron microscopy (SEM) electron spectroscopy for chemical analysis (ESCA).
    Additional Material: 8 Ill.
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  • 87
    Electronic Resource
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 931-939 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The silicone elastomer RTV-142 is often used as a particle-getter material inside electronics packages. The adhesion mechanism that forms the bond between the particle and the cured adhesive has been investigated. One expects, theoretically, that polymer chains exhibit a temperature-dependent mobility. This is consistent with the hypothesis that the flow of polymer chain segments around asperities on the foreign particles causes adhesion. Calculations of the surface energy of an idealized polymer system are presented which support the concept of a free-energetically driven flow of chain segments into pores and around asperities. Polymer surface-chain mobility is investigated experimentally by the scanning electron microscope analysis of a fractured, cut, and particle-decorated surface. Surface appearance changes were noted as a function of temperature. Scanning electron micrographs indicate that polymer chain movement is temperature dependent. Such findings support the proposed adhesion mechanism.
    Additional Material: 11 Ill.
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  • 88
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 940-946 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The electrical conductivity and the dissipation factor of silicone rubber vulcanized by the condensation reaction of α,ω-dihydroxypolysiloxane with ethoxysilane, using dibutyltin dilaurate as a catalyst, were studied. Rubber specimens, with different amounts of catalyst, were prepared using various vulcanization times and then heat treated in dry or wet atmospheres containing oxygen and nitrogen. The electrical properties of these specimens were measured at 20 to 200°C in dry air. The amounts of residual catalysts and unreacted ethoxy groups were analyzed by colorimetric and gas chromatographic methods. Factors influencing the specimen electrical properties were discussed in terms of preparation conditions and amount of residual compounds.
    Additional Material: 9 Ill.
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  • 89
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 957-961 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An approximation method is proposed to predict the Mow rate-pressure drop relation for isothermal laminar flow of any time-independent fluid in wire coating extrusion. A geometric parameter method proposed earlier is used in predict the pressure-driven flow in the annulus. The method is demonstrated for Newtonian, power law, and Ellis fluids. The accuracy of the method is shown by comparing the predictions with the theoretical and experimental results of Han and Rao. An expression for wire coating thickness is also given.
    Additional Material: 5 Ill.
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  • 90
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The properties of poly(vinyl chlorlde)/ehlorinated poly(vinyl chloride) (61.6 percent C1) blends, prepared by melt and solution blending, were measured by various tests. Based on the chlorinated poly(vinyl chloride) (CPVC) composition, percent chlorine, and mole percent CC12 groups, these blends were expected to show intermediate properties between miscible and immiscible systems. Indicative of miscible behavior were the single glass transition temperatures over the entire composition range for both melt and solution blended mixtures. A single phase was also indicated by transmission electron microscopy. However, the yield stress showed a minimum value less than either of the pure components in the 50 to 75 percent CPVC range, which is characteristic of two-phased systems. Specific volume, glass transition temperature, and heat distortion temperature were linear with binary composition. The storage modulus showed a small maximum, suggesting a weak interaction between the two miscible polymers. Heats of melting for the residual PVC crystallinity were also less than expected from linear additivity. At 160°C and 210°C, the logarithm of the complex viscosity was essentially linear with volume fraction of CPVC, except for a very slight decrease in the 50 to 75 percent CPVC range, which may have been a result of lower crystallinity. At 140°C, the complex viscosity of the CPVC was less than that of PVC owing to the higher crystallinity of the latter. The viscosities were similar at 160°C, but at 210°C, where most of the crystallites had melted, the complex viscosity of the CPVC was higher because of its higher glass transition temperature.
    Additional Material: 13 Ill.
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  • 91
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 969-974 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Twin-screw extruders are used very effectively, when partially filled, for mixing and surface renewal of high-viscosity fluids. The rate of energy input, often sufficiently high to be a major design consideration, determines the drive power, the heat input to the fluid, and the cooling requirements. Operating limitations may be fixed by thermal degradation of the material being processed. A simple model for the rate of energy dissipation in twin-screw extruders predicts that the power input is proportional to the square of the screw speed. Measurements were made of shaft torque and screw speed for polyisobutylene passing through a large twin-screw extruder having co-rotating shafts. The experimental procedure avoids the problems of changes in holdup and temperature that accompany changes in screw speed under steady state conditions. The power input was found to be proportional to the screw speed raised to the exponent 1.90. This result was attributed to slightly pseudoplastic behavior of the fluid in the radial clearances.
    Additional Material: 5 Ill.
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  • 92
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 975-981 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The steady state structure of non-isothermal free radical solution polymerization in a continuous stirred tank reactor is analyzed. With mean residence time as a bifurcation parameter, five regions of steady states are identified. The effect of reactor operating conditions on the structure and the stability of steady state is discussed.
    Additional Material: 12 Ill.
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  • 93
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 1021-1032 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This review aims to encompass various situations where optical microscopy - particularly observation and measurement of birefringence - can be used to deduce the nature of intermolecular correlations in polymers. The necessary background dealing with light propagation in anisotropic media is summarized in practical terms. The review is especially concerned with illustrating how unjustified assumptions and ambiguous terminology can cause erroneous interpretation of results. Many references cited are themselves reviews or even textbooks; they afford detailed access to the wide and diffuse literature that full coverage of this subject demands, but would constitute an unwieldly bibliography if listed as individual publications.
    Additional Material: 10 Ill.
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  • 94
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 92-102 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A realistic simulation of the injection molding process should be capable of describing moldability parameters, such as pressure drop in the delivery system and cavity and melt-front progression during cavity filling, as well as predicting the characteristics of the final product, such as residual stresses and crystallinity distributions. After a brief review of the existing models for the mathematical modeling of the injection molding process, a new model, that meets the above requirements, is proposed.
    Additional Material: 5 Ill.
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  • 95
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    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 96
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 2-2 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 97
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 54-62 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analysis is made of the thermodynamic and kinetic factors affecting phase separation in blends of di-, tri- and tetrafunctional epoxy resins, cured with either diamino-diphenylsulphone (DOS) or with dicyanodiamide (Dicy), and modified with either poly(ethersulphone) (PES) or carboxyl-terminated butadiene acrylonitrile (CTBN) rubber. The applicability and limitations of the solubility parameter approach in predicting compatibility in reactive blends are considered.
    Additional Material: 9 Ill.
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  • 98
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 82-91 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Set of procedures employing melt viscoelasticity functions for selecting components and composition of the binary polyblends and estimating minor phase domain size is introduced and illustrated with examples. The procedures intended for Computer Aided Manufacture of the polyblends (CAMOBLE) are based on shear stress dependent viscoelasticity ratios, and the selection of the composition exploits stress dependent synergism of the viscoelasticity functions. Also used is auxilary procedure for composition selection is based on verified blending laws accounting for interaction and shear effects. Evaluation of the performance characteristics (“mechanical properties”) is illustrated with a modified Kerner model.
    Additional Material: 12 Ill.
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  • 99
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 116-119 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 144-151 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic responses of a 2-1/2 inch single screw plasticating extruder and extrusion line were investigated. Step changes in screw speed, take-up speed, back pressure, and processing materials were used to determine the transient responses of barrel pressures, die pressure, melt temperature, and extrudate thickness. Dynamic responses of the entire extrusion line can be explained by the flow mechanism of the extruder and the logical properties of the polymer used. A capillary rheometer was also used to determine if it could simulate pressure responses in the extruder for screw speed changes. Results showed that capillary rheometer was helpful in estimating the short term pressure responses in the die.
    Additional Material: 13 Ill.
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