98 research outputs found

    Development of a petrographic classification of fly-ash components from coal combustion and co-combustion. (An ICCP Classification System, Fly-Ash Working Group – Commission III.)

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    A new system for the microscopic classification of fly-ash components has been developed by the Fly-Ash Working Group, Commission III of the ICCP and is presented herein. The studied fly-ashes were obtained from the combustion of single coals of varied rank, coal blends, and coals blended with other fuels (biomass, petroleum coke), in different operating conditions and by means of different technologies. Microscopic images of the fly-ash samples were used to test the optical criteria proposed for classifying the fly-ash components. The classification system developed is based on a small number of microscopic criteria, subdivided into six independent levels or categories, three of which are directed at whole particle identification on the basis of nature, origin and type of fly-ash particle, while the other three levels are directed at the smaller section identification on the basis of character, structure and optical texture of unburned carbons. To classify the inorganic components of the fly-ash, the criterion proposed is composition in terms of metallic/non-metallic character. To establish the classification criteria the petrographers involved in the work performed three successive round robins. Evaluation of the results by using firstly descriptive statistics and then the criteria and parameters employed by the ICCP in their accreditation programs indicated that the classification of the fly-ash components was accurate and that there was only a minor bias. The main conclusion of this study was that the proposed criteria are valuable for identifying, and classifying fly-ash components and for describing the optical properties of fly-ash particles

    Renewable polymers and plastics: Performance beyond the green

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    Renewable bio-based polymers are one of the effective answers that the bioeconomy offers to solve the environmental emergency connected to plastics and more specifically fossil-based plastics. Previous studies have shown that more than 70 % of the natural capital cost associated with plastic derives from the extraction and processing of fossil raw materials and that the price of fossil plastic would be on average 44 % higher if such impact was fully paid by businesses. The disclosure of the hidden costs of plastics will contribute to dispelling the myth of the expensiveness of renewable polymers. Nevertheless, the adoption of bio-based plastics in the market must be motivated by their functional properties and not merely by their green credentials. This article highlights some successful examples of synergies between chemistry and biotechnology in achieving a new generation of bio-based monomers and polymers. Their success is justified by the combination of scientific advances with positive environmental and social fallouts

    CHARACTERIZATION OF CURED RUBBER MODIFIED POLYESTER RESINS BY NUCLEAR MAGNETIC-RESONANCE METHODS

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    The cure reaction of rubber-modified unsaturated polyester resins was investigated by 13C-NMR of the hydrolysis products as function of the type and amount of rubber in the resin. A relation was found between the type of terminal groups present on the poly(butadiene) rubber and the length of polystyrene bridges cross-linking the polyester chains

    Variation in Sulfur Dioxide Emissions Related to Earth Tides, Halemaumau Crater, Kilauea Volcano, Hawaii

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    Variation in SO2 emissions from Halemaumau crater, Kilauea volcano, Hawaii is analyzed using a set of techniques known as exploratory data analysis. SO2 flux was monitored using a correlation spectrometer. A total of 302 measurements were made on 73 days over a 90‐day period. The mean flux was 171 t/d with a standard deviation of 52 t/d. A significant increase in flux occurs during increased seismic activity beneath the caldera. SO2 flux prior to the this change varies in a systematic way and may be related to variation in the tidal modulation envelope
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