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Organic Vapors (organic + vapor)

Distribution by Scientific Domains
Chemistry42%

Terms modified by Organic Vapors

  • organic vapor phase epitaxy
    		•

    Selected Abstracts

    Electrical Response to Organic Vapor of Conductive Composites from Amorphous Polymer/Carbon Black Prepared by Polymerization Filling

    MACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2003
    Jun Rong Li
    Abstract In recent years, conductive polymer composites have found applications as gas sensors because of their sudden change in electric resistance of several orders of magnitude when the materials are exposed to certain solvent vapors. However, the composites having this function reported so far are mostly based on crystalline polymeric matrices, which factually sets a limit to materials selection. The present work prepares polystyrene/carbon black composites through polymerization filling and proves that the amorphous polymer composites can also serve as gas sensing materials. The composites' percolation threshold is much lower than that of the composites produced by dispersive mixing. In addition, high responsivity to some organic vapors coupled with sufficient reproducibility is acquired. The experimental data show that molecular weight and molecular weight distribution of the matrix polymer and conducting filler content exert great influence on the electrical response behavior of the composites. As a result, composites performance can be purposely tailored accordingly. Compared with the approaches of melt-blending and solution-blending, the current technique is characterized by many advantages, such as simplicity, low cost, and easy to be controlled. Effect of different organic solvent vapors on the electric resistance of PS/CB composites (CB content,=,10.35 vol.-%). [source]

    Comparison of Fixed and Fluidized Activated Carbon Beds for Removal of Organic Vapors

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2004
    I.E. Agranovski
    Abstract Activated carbons are commonly used for removal of organic vapors from exhaust air streams. Two configurations, including fixed and fluidized carbon beds are usually employed in industry to meet various requirements of the industrial process which is being used. This paper investigates the performance of such configurations and provides a comparative analysis. It was found that for thin carbon layers, the fixed bed performs more efficiently with the difference exceeding 15,% for the layers with the thickness less than 15,mm. This difference is decreasing with increase of the layer thickness and becomes less than 5,% for the beds thicker than 100,mm. Considering various advantages of the fluidized beds over fixed beds, including lower resistance to the gas flow, excellent gas distribution and minimal possibility of clogging in case of existence of alien particles in the gas, they are recommended for use with the minimal thickness of the layer to be larger than 100,mm. [source]

    Estimating exposures in the asphalt industry for an international epidemiological cohort study of cancer risk

    AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2003
    Igor Burstyn
    Abstract Background An exposure matrix (EM) for known and suspected carcinogens was required for a multicenter international cohort study of cancer risk and bitumen among asphalt workers. Methods Production characteristics in companies enrolled in the study were ascertained through use of a company questionnaire (CQ). Exposures to coal tar, bitumen fume, organic vapor, polycyclic aromatic hydrocarbons, diesel fume, silica, and asbestos were assessed semi-quantitatively using information from CQs, expert judgment, and statistical models. Exposures of road paving workers to bitumen fume, organic vapor, and benzo(a)pyrene were estimated quantitatively by applying regression models, based on monitoring data, to exposure scenarios identified by the CQs. Results Exposures estimates were derived for 217 companies enrolled in the cohort, plus the Swedish asphalt paving industry in general. Most companies were engaged in road paving and asphalt mixing, but some also participated in general construction and roofing. Coal tar use was most common in Denmark and The Netherlands, but the practice is now obsolete. Quantitative estimates of exposure to bitumen fume, organic vapor, and benzo(a)pyrene for pavers, and semi-quantitative estimates of exposure to these agents among all subjects were strongly correlated. Semi-quantitative estimates of exposure to bitumen fume and coal tar exposures were only moderately correlated. EM assessed non-monotonic historical decrease in exposures to all agents assessed except silica and diesel exhaust. Conclusions We produced a data-driven EM using methodology that can be adapted for other multicenter studies. Am. J. Ind. Med. 43:3,17, 2003. © 2003 Wiley-Liss, Inc. [source]

    Chemical Reactivity of Polypyrrole and Its Relevance to Polypyrrole Based Electrochemical Sensors

    ELECTROANALYSIS, Issue 16 2006
    Krzysztof MaksymiukArticle first published online: 26 JUL 200
    Abstract One of the most frequently used conducting polymers, polypyrrole, can take part in chemical processes with typical components of ambient media: oxygen, acids, bases, redox reactants, water, and organic vapors; it can also incorporate nonreactive ions and surfactants from solutions. The influence of such processes on changes of the polymer structure, composition and on possible degradation is analyzed. The benefits and disadvantages of such processes for analytical characteristic of polypyrrole based electrochemical sensors are considered. This discussion is focused on potentiometric ion sensors, where polypyrrole is either a receptor membrane or an ion-to-electron transducer placed between a solid state electrode support and a typical ion-selective membrane. [source]

    Electrical Response to Organic Vapor of Conductive Composites from Amorphous Polymer/Carbon Black Prepared by Polymerization Filling

    MACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2003
    Jun Rong Li
    Abstract In recent years, conductive polymer composites have found applications as gas sensors because of their sudden change in electric resistance of several orders of magnitude when the materials are exposed to certain solvent vapors. However, the composites having this function reported so far are mostly based on crystalline polymeric matrices, which factually sets a limit to materials selection. The present work prepares polystyrene/carbon black composites through polymerization filling and proves that the amorphous polymer composites can also serve as gas sensing materials. The composites' percolation threshold is much lower than that of the composites produced by dispersive mixing. In addition, high responsivity to some organic vapors coupled with sufficient reproducibility is acquired. The experimental data show that molecular weight and molecular weight distribution of the matrix polymer and conducting filler content exert great influence on the electrical response behavior of the composites. As a result, composites performance can be purposely tailored accordingly. Compared with the approaches of melt-blending and solution-blending, the current technique is characterized by many advantages, such as simplicity, low cost, and easy to be controlled. Effect of different organic solvent vapors on the electric resistance of PS/CB composites (CB content,=,10.35 vol.-%). [source]

    Comparison of Fixed and Fluidized Activated Carbon Beds for Removal of Organic Vapors

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2004
    I.E. Agranovski
    Abstract Activated carbons are commonly used for removal of organic vapors from exhaust air streams. Two configurations, including fixed and fluidized carbon beds are usually employed in industry to meet various requirements of the industrial process which is being used. This paper investigates the performance of such configurations and provides a comparative analysis. It was found that for thin carbon layers, the fixed bed performs more efficiently with the difference exceeding 15,% for the layers with the thickness less than 15,mm. This difference is decreasing with increase of the layer thickness and becomes less than 5,% for the beds thicker than 100,mm. Considering various advantages of the fluidized beds over fixed beds, including lower resistance to the gas flow, excellent gas distribution and minimal possibility of clogging in case of existence of alien particles in the gas, they are recommended for use with the minimal thickness of the layer to be larger than 100,mm. [source]

    Effect of protective filters on fire fighter respiratory health during simulated bushfire smoke exposure

    AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 9 2006
    Annemarie J.B.M. De Vos RN
    Abstract Background Bushfire fighters are potentially subject to risks from bushfire smoke. Although many different protective masks and filters are available, it is not clear which is the most effective from a health and safety perspective. The effect of protective filters on the respiratory health of Western Australian urban career fire fighters under controlled simulated conditions is investigated. Methods Sixty-four healthy Fire and Emergency Services Authority of Western Australia (FESA) urban career fire fighters were subjected to controlled simulated bushfire smoke in an open smoke chamber for 15 min. The fire fighters were allocated one of the three types of protective filters: particulate only (P), particulate/organic vapor (POV), and a particulate/organic vapor/formaldehyde (POVF) filter using a double-blind randomized procedure. Personal air sampling inside the fire fighters' masks, spirometry, oximetry, and self-reported symptom data were collected at baseline and at two time intervals after the smoke exposure. Results A significant decline in oxygen saturation was seen immediately after exposure, however, the decline was small and no significant relationships could be established between this and the type of filter used. A significantly higher number of participants in the P and POV filter groups self-reported an increase in coughing, wheezing, and shortness of breath compared to the POVF group. Air sampling demonstrated a significantly higher level of formaldehyde and acrolein inside the masks fitted with P filters compared to POV and POVF filters. Conclusions Testing the effectiveness of P, POV, and POVF filters under controlled conditions has demonstrated that the POVF filter provides statistically significant better protection for the fire fighters' airways in a simulated bushfire exposure chamber. Am. J. Ind. Med. © 2006 Wiley-Liss, Inc. [source]