No description available.

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references (leaves 240-249). Also available via World Wide Web.

Thesis (M.S.)--Ohio University, August, 2000. / Title from PDF t.p.

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No description available.

Thesis (M.S.)--Ohio University, August, 1985. / Title from PDF t.p.

Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town,1996 / Acetylene Black IACB) IS a pure form of carbon which is used in the battery, plastics, printing and rubber industries. It is extensively used in the battery industry to absorb electrolyte and to lower the electrical resistance of dry cell batteries. It is the attempt of this thesis, to investigate the surface characteristics '---------._-- -,- ...• -...•--- .. ------.. _.. --- "'- and structure of ACB by using it as an adsorbent for cyanide complexes, in particular gold cyanide. The thesis is predominantly aimed at identifying the mechanism of metal cyanide adsorption onto ACB, viz. ion exchange and/or physical adsorption. In order to quantify the mechanism of adsorption, comparative studies with other adsorbents currently used in the mining industry, such as activated carbon, were conducted. These studies revealed various similarities in the metal adsorption process between ACB and activated carbon, thus indicating physical adsorption rather than ion exchange to be the dominant mechanism for metal adsorption from solution. The rate of metal adsorption onto acetylene black was relatively fast compared to activated carbon. Furthermore, adsorption profiles revealed that intraparticle diffusion was negligible when a metal was adsorbed onto ACB from solution. This indicates that acetylene black has a predominantly amorphous structure, although X-ray diffractrometry indicates a certain degree of graphitisation associated with ACB. The small surface area of ACB, together with the lack of intraparticle diffusion, resulted in the rapid attainment of the equilibrium metal loading on ACB. Moreover, this equilibrium metal loading was far less than that of activated carbon and ionexchange resin. While pH, temperature and strong oxidizing agents had a marked effect on the adsorption profile of metal cyanides onto ACB, the effect of oxygen enrichment and organic solvents was negligible. Furthermore, the adsorption of gold onto ACB is best explained by a Freundlich-type isotherm. As is the case with activated carbon and ion exchange resin, gold is eluted from ACB by a NaOH solution. It was also found that the elution efficiency is influenced by a change in temperature. Changes in operating variables in the production of ACB had an effect on the absorption stiffness of the product. Both an increase in acetylene feed rate and operating temperature reduced the absorption stiffness of the product.

No description available.

Abstract: The carbon black material used as reinforcing filler in tires was recovered by pyrolysis at a temperature of 490¢XC and at atmospheric pressure. The pyrolytic carbon black obtained (CBp) was contamined by various additives of the original tire. Contaminants were also produced by chemical reactions occurring in the pyrolysis reactor. The recovered carbon black was performed and a possible reduction of the ash content by hydrochloric acid treatment. After the demineralization treatment, the recovered pyrolytic carbon black (CBP) was heated in a post-pyrolysis process at temperatures ranging from 670 to 1170 ¢XC. The CBP were studied by low-pressure nitrogen adsorption and surface spectroscopic method ( SIMS), Raman spectroscopy, XRD, TPD, TEM. Furthermore, the CBP properties were correlated to their electrical conductivities.

The degree of carbon black dispersion is a very important consideration in the manufacture of rubber both in quality control and basic research. A study has been made of various aspects of assessing dispersion and the dispersion process of carbon black in rubber. The main objectives of this work were: (1) To investigate the relationship between the light scattered at a fixed angle from the rubber surface and carbon black dispersion and hence develop and evaluate a new dispersion assessment system. (2) To determine the normal variations of industrial rubber mixing installations, and (3) To study the effect of internal mixing variables on black dispersion and other properties of rubber. To achieve these goals a carbon black dispersion assessment system based on an inverted Dark Field Reflected Light (D.F.R.L.) microscope was developed in three versions and successfully tested. The three versions differed in their degree of sophistication and automation and would be expected to find application ranging from routine quality control to research. The basic principle was that a rubber sample (cured or uncured) was cut with a new razor blade and the surface observed in a D.F.R.L. microscope. The light beam from the sample surface is sensed by a photometer and its intensity was shown to be related to black dispersion. In version III an automatic stage driven by two stepper motors was designed and fitted to the microscope to perform object plane scanning. The photometer and the stage were interfaced with an Apple II microcomputer providing the following functions; stage control, photometer control, data acquisition, statistical analysis, data storage and results output. The system was evaluated by taking measurements on several identically formulated compounds differing only in black dispersion. A general rubber goods and a tyre manufacturing installation were studied. Several production batches were sampled at various mixing stages and subjected to black dispersion assessment, cure and vulcanisate properties measurement. Analysis of variance of the results was accomplished with a statistical computer package designated GENSTAT Version 4.03. Factorial experimental designs and multivariate regression analysis techniques were used in studying the effect of mixing variables on black dispersion and other properties. The results are presented in the form of response equations and contour graphs are used to enable second order interactions to be readily identified.