Under certain conditions, reactive chemicals may proceed into uncontrolled chemical reaction pathways with rapid and significant increases in temperature, pressure, and/or gas evolution. Reactive chemicals have been involved in many industrial incidents, and have harmed people, property, and the environment. Evaluation of reactive chemical hazards is critical to design and operate safer chemical plant processes. Much effort is needed for experimental techniques, mainly calorimetric analysis, to measure thermal reactivity of chemical systems. Studying all the various reaction pathways experimentally however is very expensive and time consuming. Therefore, it is essential to employ simplified screening tools and other methods to reduce the number of experiments and to identify the most energetic pathways. A systematic approach is presented for the evaluation of reactive chemical hazards. This approach is based on a combination of computational methods, correlations, and experimental thermal analysis techniques. The presented approach will help to focus the experimental work to the most hazardous reaction scenarios with a better understanding of the reactive system chemistry. Computational methods are used to predict reaction stoichiometries, thermodynamics, and kinetics, which then are used to exclude thermodynamically infeasible and non-hazardous reaction pathways. Computational methods included: (1) molecular group contribution methods, (2) computational quantum chemistry methods, and (3) correlations based on thermodynamic-energy relationships. The experimental techniques are used to evaluate the most energetic systems for more accurate thermodynamic and kinetics parameters, or to replace inadequate numerical methods. The Reactive System Screening Tool (RSST) and the Automatic Pressure Tracking Adiabatic Calorimeter (APTAC) were employed to evaluate the reactive systems experimentally. The RSST detected exothermic behavior and measured the overall liberated energy. The APTAC simulated near-adiabatic runaway scenarios for more accurate thermodynamic and kinetic parameters. The validity of this approach was investigated through the evaluation of potentially hazardous reactive systems, including decomposition of di-tert-butyl peroxide, copolymerization of styrene-acrylonitrile, and polymerization of 1,3-butadiene.

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Chemical reactivity hazards have posed a significant challenge for industries that manufacture, store, and handle reactive chemicals. Without proper management and control of reactivity, numerous incidents have caused tremendous loss of property and human lives. The U.S. Chemical Safety and Hazard Investigation Board (CSB) reported 167 incidents involving reactive chemicals that occurred in the U.S. from 1980 to 2001. According to the report, 35 percent of the incidents were caused by thermal runaway reactions, such as incidents that involved hydroxylamine and hydroxylamine nitrate. The thermal stability of hydroxylamine system under various industrial conditions was studied thoroughly to develop an understanding necessary to prevent recurrence of incidents. The macroscopic runaway reaction behavior of hydroxylamine system was analyzed using a RSST (Reactive System Screening Tool) and an APTAC (Automatic Pressure Tracking Calorimeter). Also, computational chemistry was employed as a powerful tool to evaluate and predict the measured reactivity. A method was proposed to develop a runaway reaction mechanism that provides atomic level ofinformation on elementary reaction steps, in terms of reaction thermochemistry, activation barriers, and reaction rates. This work aims to bridge molecular and macroscopic scales for process safety regarding reactive chemicals and to understand macroscopic runaway reaction behaviors from a molecular point of view.

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Under certain conditions, reactive chemicals may proceed into uncontrolled chemical reaction pathways with rapid and significant increases in temperature, pressure, and/or gas evolution. Reactive chemicals have been involved in many industrial incidents, and have harmed people, property, and the environment. Evaluation of reactive chemical hazards is critical to design and operate safer chemical plant processes. Much effort is needed for experimental techniques, mainly calorimetric analysis, to measure thermal reactivity of chemical systems. Studying all the various reaction pathways experimentally however is very expensive and time consuming. Therefore, it is essential to employ simplified screening tools and other methods to reduce the number of experiments and to identify the most energetic pathways. A systematic approach is presented for the evaluation of reactive chemical hazards. This approach is based on a combination of computational methods, correlations, and experimental thermal analysis techniques. The presented approach will help to focus the experimental work to the most hazardous reaction scenarios with a better understanding of the reactive system chemistry. Computational methods are used to predict reaction stoichiometries, thermodynamics, and kinetics, which then are used to exclude thermodynamically infeasible and non-hazardous reaction pathways. Computational methods included: (1) molecular group contribution methods, (2) computational quantum chemistry methods, and (3) correlations based on thermodynamic-energy relationships. The experimental techniques are used to evaluate the most energetic systems for more accurate thermodynamic and kinetics parameters, or to replace inadequate numerical methods. The Reactive System Screening Tool (RSST) and the Automatic Pressure Tracking Adiabatic Calorimeter (APTAC) were employed to evaluate the reactive systems experimentally. The RSST detected exothermic behavior and measured the overall liberated energy. The APTAC simulated near-adiabatic runaway scenarios for more accurate thermodynamic and kinetic parameters. The validity of this approach was investigated through the evaluation of potentially hazardous reactive systems, including decomposition of di-tert-butyl peroxide, copolymerization of styrene-acrylonitrile, and polymerization of 1,3-butadiene.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed July 9, 2007). PDF text: 111 p. : ill. UMI publication number: AAT 3251358. Includes bibliographical references. Also available in microfilm and microfiche formats.

The benefits of applying microwave energy to material processing techniques have been well documented and studied. The potential benefits over conventional oven heating include faster processing times, more uniform heating, more consistent product quality, and the possibility of precise control. The actual implementation of microwave technology has been lacking and the benefits have gone largely unrealized. This is due in part to the temperature dependence of the dielectric loss of many industrial materials such as ceramics and polymers. These materials absorb more microwave energy as they heat, creating uncontrollable heating, often called 'thermal runaway'. The focus of this research is to address this challenge. The work described here is an experimental program for the microwave processing of specific ceramic rods and polymer tows. The objective of the program is to study the thermal runaway effect, and to provide data which will be used to verify numerical models. Accurate test data are essential to the development of precise, comprehensive models that can be used in applicator design and heating control strategies for thermal runaway materials. The experimental program explores the difficulties of microwave heating and offers solutions to more efficient systems. Successful measurements of power loss and control of thermal runaway are detailed for mullite, alumina, and nylon. / Master of Science

<p>Aim:The study's aim is to examine whether and to what extent elementary school pupils aged 13 and 16 report that they ever have been forced to leave home by parents, have run away from home voluntarily or have seriously considered doing so. The aim is also to illuminate which circumstances contribute to these break-ups. Method: A quantitative approach is used; a survey material consisting of 1193 questionnaires is analysed. The data material has been used in earlier studies but the issue addressed here has not been studied earlier. The circumstances analysed are gender, ethnicity, the parents’ religious belief and education, living conditions (sharing home with both parents, one of them or none), contacts with professionals (psychologist, school nurse or curator), physical and mental wellbeing, way of upbringing (liberal vs authoritarian) and communication with parents. The findings are compared to a similar study from Great Britain. Results: The results show that 4 percents of the young people have been forced to leave home some time during their life and 9 percent have run away and stayed away for at least 24 hours. The proportion of young people seriously considering leaving home was 22 percents. It is concluded that being forced to leave home has different explanations compared to running away by own decision. It is thus two different phenomena. A few risk factors are identified.</p>

Aim:The study's aim is to examine whether and to what extent elementary school pupils aged 13 and 16 report that they ever have been forced to leave home by parents, have run away from home voluntarily or have seriously considered doing so. The aim is also to illuminate which circumstances contribute to these break-ups. Method: A quantitative approach is used; a survey material consisting of 1193 questionnaires is analysed. The data material has been used in earlier studies but the issue addressed here has not been studied earlier. The circumstances analysed are gender, ethnicity, the parents’ religious belief and education, living conditions (sharing home with both parents, one of them or none), contacts with professionals (psychologist, school nurse or curator), physical and mental wellbeing, way of upbringing (liberal vs authoritarian) and communication with parents. The findings are compared to a similar study from Great Britain. Results: The results show that 4 percents of the young people have been forced to leave home some time during their life and 9 percent have run away and stayed away for at least 24 hours. The proportion of young people seriously considering leaving home was 22 percents. It is concluded that being forced to leave home has different explanations compared to running away by own decision. It is thus two different phenomena. A few risk factors are identified.

Thesis (M.S.W.)--University of Hong Kong, 1994. / Includes bibliographical references (leaves 52-54).