摘要:

The natural rubber field latex of various rubber estates of Bangladesh was analyzed. The total solid content, dry rubber content, alkalinity, KOH number, volatile fatty acid number, pH, viscosity, density, sludge content, and coagulum content of the latex; and the ash content, water-insoluble ash content, nitrogen content, and metal content—such as iron, manganese, and copper—in the total solid were determined. These properties were compared between latexes of different clones and the ages of the rubber trees. The total solid content of the latex varies from 19% to 45% and it increases with increased age of rubber trees. The protein content decreases with increased age of the trees. Density decreases with increased rubber content of the latex. Viscosity is dependent on the total solid content of the latex; it increases with increased total solids in the latex. The concentrations of copper and manganese are below 6 ppm but that of iron is between 12 and 43 ppm.

ISSN:0360-2559    

DOI:10.1080/03602559508015822

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The evaluation of petroleum-based paving asphalts as a possible source of heavy metal pollution in soils and water, as well as the determination of combustion parameters—smoke mass and particle size distribution, and sulfur dioxide and oxides of nitrogen during controlled burning—represented the main goals of this study. Special consideration was given to the changes in combustion behavior, smoke components, and heavy metal content introduced by the addition of tire rubber to the paving asphalt samples. The different analytical techniques applied were conducted on samples of pure asphalt cement (including different brands and grades), samples of asphalt rubber (with concentrations of 4%, 10%, and 18% of tire rubber), and samples of asphalt concrete taken from two different locations in the city of College Station, Texas. Instrumental neutron activation analysis (INAA) was used to identify and quantify the heavy metals present in the asphalts. Zinc, manganese, and vanadium were the most prevalent metallic constituents. Zinc was generally found in the highest concentrations while manganese was present in all the samples analyzed. The study showed increasing levels of zinc (range of 1,040 ppm to 2560 ppm) with corresponding higher levels of tire rubber content. Total absence of nickel in all of the samples tested implies the need for longer INAA radiation times and/or the need to resort to other analytical methods such as atomic absorption since both nickel and vanadium are present in the porphyrin complex structures in the crudes from which the asphalts originated. The evaluation of different samples of asphalt under controlled combustion showed that more than 90% of the smoke particles emitted by all the samples were less than 10 μm in diameter and, thus, are easily inhaled deep into the human respiratory system. It was also observed that the amount of smoke generated by samples of asphalt containing rubber was up to 43% higher than the amount of smoke produced by samples of the same brand and grading but with no tire rubber present. The analysis of the gaseous smoke components on a Bachrach Model 300 NSX Combustion Analyzer showed very low levels of NOxbut higher amounts of SO2. The latter SO2levels were in the expected range based on the common practice of using sour crude oils (approx. 1% sulfur) for asphalt production, but they were less than the expected sulfur content in rubber after the vulcanization process. Nevertheless, the relative concentrations of SO2gave approximate yield values as high as 7.42 L of SO2/kg asphalt. Depending on prevailing wind conditions this yield could present a threat to human life, such as during a fire in an asphalt tank or an asphalt-processing facility, or during an accidental ignition of hydrocarbons on an asphaltic surface from an overturned or ruptured fuel delivery truck. The results of this study support the hypothesis that more attention should be given to the potential global pollutant effects of paving asphalts because of the enormous quantities utilized each year and their nonpermanence. Research regarding the environmental effects of using tire rubber as a paving additive also needs to be more rigorously addressed.

ISSN:0360-2559    

DOI:10.1080/03602559508015823

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The chemistry of different routes to the manufacture of vinyl chloride monomer is discussed. Their economic advantages and drawbacks are considered. The balanced process for ethylene-based vinyl chloride production is discussed in detail and an overall process for the same is described. The effects of catalyst, temperature, and reaction steps on product and by-product are analyzed. Recent trends in vinyl chloride processes result in energy savings and have fewer side reactions and increased conversion levels. Future trends such as mixed-gas feedstocks and patents are hinted at.

ISSN:0360-2559    

DOI:10.1080/03602559508015824

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Poly(ethy1ene terephthalate), PET, is a semicrystalline thermoplastic polymer which has proven to be extremely valuable as a raw material for the production of fibers and oriented film products. Yarns and fabrics manufactured from PET polyester fibers are used in everything from clothing to heavy-duty industrial fabrics and load-bearing reinforcements. PET films are widely used for food packaging, and PET bottles for carbonated beverages have become commonplace.

ISSN:0360-2559    

DOI:10.1080/03602559508015825

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A mathematical analysis has been performed to investigate the combined effects of viscosity and elasticity on the interfacial and the surface stabilities of two superposed Oldroyd-B fluids flowing down an inclined plane. Our results indicate that arranging the less viscous and more elastic liquid as the skin layer is helpful in avoiding the occurrence of interfacial waves. For the stability of free surface, it is found that the elasticity in each layer is always destabilizing free surface waves. However, this destabilization can be lessened by designing the more viscous liquid as the skin layer. In addition, the effect of increasing Reynolds number on the interface and the free surface is investigated. It is shown that increasing Reynolds number can stabilize or destabilize the interface, depending on the parametric space of the flow system. However, free surface is always destabilized by an increase in Reynolds number. In general, our analysis indicates that under certain physical conditions (i.e., viscosity and elasticity ratios) and geometric conditions (i.e., depth ratio), stable operations in the coating process can be attained.

ISSN:0360-2559    

DOI:10.1080/03602559508015826

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper summarizes and reviews research in electromagnetic interface (EMI) shielding based on the review of over 300 articles which are presented in four separate categories. It will be noticed, however, that some articles are cited in more than one category. At the end of each subcategory. a summary is given for easy reference. A table relating each subcategory to the given references at the end of this paper is also supplied. The document comprises a comprehensive study of basic concepts in EMI shielding, analytical and numerical modeling techniques, test methods and instrumentations, material selection, and factors involved in shielding degradation. Cost comparison for various shielding techniques, and the advantages and disadvantages of using the different types of shielding materials and testing methods are reviewed.

ISSN:0360-2559    

DOI:10.1080/03602559508015827

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The electronic absorption spectra of dithizone (H2DZ) and its metal complexes of Hg. Cd, and Zn doped in poly(methyl methacrylate), PMMA has been investigated before and after γ-irradiation. It is found that the complex formation resulted in significant changes in both the position and the intensity of the electronic bands of H2DZ. γ-Radiation causes remarkable decrease in the intensity of the most absorption bands of the metal complexes. The rate of decrease depends on the nature of the metal ions.

ISSN:0360-2559    

DOI:10.1080/03602559508015828

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Traditional Korshak's Readings were as always held January 11–12, 1994, around the birth date of Professor Vasilii V. Korshak, who was a founder of the synthetic polymer school in former Soviet Union and was at the head of polymer science in the USSR for a long time. Among his disciples there are 200 philosophy doctors and 40 doctors of science. This year the Readings were dedicated to the 85th Anniversary of Professor Korshak's birthday (January 9, 1909). They were organized by the Scientific Council on Macromolecules of the Division of Pure and Applied Chemistry of the Russian Academy of Sciences, Nesmeyanov Institute of Elementoorganic Compounds of the Russian Academy of Sciences (IEOC), and Mendeleev Russian University of Chemistry and Technology. The Organizing Committee involved well-known colleagues and disciples of Professor V. V. Korshak. They were Professors A. L. Rusanov (the chairman), A. A. Askadsky, P. M. Valetsky, V. A. Vasnev, S. V. Vinogradova, Ya. S. Vygodsky, V. A. Davankov, V. V. Kireev, and A. R. Khokhlov. About 100 scientists from 15 research centers contributed in the conferences.

ISSN:0360-2559    

DOI:10.1080/03602559508015829

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This report describes an annual session of the Polymer Flammability Group of the Scientific Council on Combustion and Explosion. The session was focused upon summing up scientific activity of the institutes of the Russian Academy of Sciences in the area of polymer flammability. The members of the Council and invited experts totalling about 100 scientists from 15 research centers of the Russian Academy participated in this session.

ISSN:0360-2559    

DOI:10.1080/03602559508015830

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0360-2559    

DOI:10.1080/03602559508015821

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor