1,720,971 research outputs found
The thermal degradation process of tetrabromobisphenol A
No full textThis study focused on the investigation of the thermal degradation process of tetrabromobisphenol A (TBBA). The use of combined experimental techniques allowed the quantitative characterization of TBBA decomposition products and the analysis of the thermal degradation rates. The distribution of bromine among the different decomposition product fractions was investigated. In the open configuration used for the experiments, hydrogen bromide, brominated bisphenol A species, and brominated phenols resulted in the main decomposition products. Bromine was mainly evolved as hydrogen bromide, although a relevant quantity resulted present in the primary high molecular weight condensable product fraction, in agreement with the decomposition pathways proposed. The results evidenced that accidents involving TBBA thermal degradation, such as fire or process runaways, may pose relevant safety problems because of the possible release of considerable quantities of hazardous decomposition products
The use of TG-FTIR technique for the assessment of hydrogen bromide emissions in the combustion of BFRs
No full textThe TG-FTIR technique was used in the present study to investigate the thermal degradation behaviour of materials containing brominated flame retardants under fire conditions. Time-temperature profiles and oxygen concentrations typical of selected fire scenarios were reproduced in the thermogravimetric analyzer, while the characterization of the gaseous products generated was performed by the simultaneous FTIR analysis. FTIR analysis combined with the use of specific calibration procedures allowed the quantitative estimation of the gaseous products evolved as a function of experimental conditions. The results obtained allowed the straightforward assessment and the comparison of the quantities of hydrogen bromide formed in the oxidation and thermal degradation of pure brominated flame retardants and of flame retarded materials of industrial interest. Hydrogen bromide yields resulted dependent on the experimental conditions used, such as oxygen concentration and heating rate. Although TG-FTIR experiments only provide a representation of the actual heterogeneous combustion products in real fire conditions, the coupled TG-FTIR technique proved to be a straightforward experimental methodology allowing one to obtain reference data on the nature and quantities of the macropollutants generated in a fire
Different scale experimental techniques to approach the problem of substances generated in the loss of control of chemical systems: a study on ethyldiazoacetate decomposition products
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Formation of hazardous substances in the loss of control of chemical systems: the case of brominated flame retardants
No full textAdvanced pulse calibration techniques for the quantitative analysis of TG-FTIR data
No full textTwo different pulse calibration techniques to estimate the total quantities of evolved gaseous substances formed in thermogravimetric (TG)-FTIR runs were compared and assessed. A gas-pulse calibration method was based on the use of a specific device able of sending a known quantity of a gaseous compound of interest to the FTIR analyzer. A second calibration method was based on the vaporization in the TG analyzer of liquid solutions of the compound of interest. Data obtained by these techniques were compared to those from conventional concentration-based calibration. The results confirmed the reliability of pulse calibration techniques to obtain quantitative data on evolved gaseous products in TG-FTIR applications. Moreover, both the gas-pulse and the vaporization-based calibration techniques proved to have several advantages with respect to conventional techniques. Among these are the need of a more limited number of standards and no need for online gas dilution systems. (C) 2002 Elsevier Science B.V. All rights reserved
Experimental Strategies for the Identification of Products Formed in the Loss of Control of Chemical Systems
No full textThermal degradation and decomposition products of electronic boards containing BFRs
No full textProduction of electronic boards containing brominated flame retardants is constantly increasing, posing important problems with disposal of products containing these materials. The present study investigated the thermal degradation behavior of electronic boards manufactured using tetrabromobisphenol A and diglycidyl ether of bisphenol A epoxy resins. Qualitative and quantitative information was obtained on the products formed in the thermal degradation process, and the bromine distribution in the different product fractions was determined. The more important decomposition products included hydrogen bromide, phenol, polybrominated phenols, and polybrominated bisphenol A species. The formation of considerable amounts of hydrogen bromide and high-molecular-weight organobrominated compounds, as well as the potential formation of limited quantities of polybrominated dibenzo-p-dioxins and dibenzofurans, is an important element of concern in the safety and environmental assessment of the thermal degradation processes of electronic boards containing brominated flame retardants
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