Thesis (Ph. D.)--University of Michigan, 1935. / "By A.L. Ferguson, L.O. Case and G. Harlowe Evans." From Journal of chemical physics, v. 3, May, 1935.

Thesis (Ph. D.)--Kings College, Cambridge, 1966. / Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, 1917. / "Reprinted from the Physical review, N.S., Vol. XVII, No. 3, March, 1921." Includes bibliographical references. Also available on the Internet.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2009. / Includes bibliographical references (leaves 84-89). Also available online.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 97-101). Also available on the Internet.

Two novel methods for the sulphur vulcanisation of NR, BR and EPDM rubbers using N-tert-butyl-2-benzothiazole sulphenamide (TBBS) accelerator and zinc oxide (ZnO) activator have been developed. In one method, the optimum loading of TBBS and ZnO were measured for some sulphur-filled NR, BR and EPDM rubbers. The cure systems for the NR were (S/TBBS/ZnO), (1/1.5/0.2), (2/1.5/0.3), (3/1.5/0.25), and (4/3.5/0.2), for the BR, (0.5/1.75/0.2) and (1/3/0.2), and for the EPDM, (1/1/0.075). The cure was very efficient in spite of reducing the amount of TBBS and ZnO chemicals. In another method which used a single additive component in the form of a powder (TBBS/ZnO: 350mg/1g), the loading of the powder in NR was raised increasingly from 0.63 to 5.63 phr, the scorch time was unchanged and the optimum cure time reduced at 1.25 phr powder. The rate of cure accelerated at 1.25 phr powder. The crosslink density reached its maximum value at 5.63 phr powder. This method reduced the TBBS and ZnO requirement in the cure system by 85wt%. Solid kaolin filler pre-treated with a sulphur-bearing mercaptosilane was used to reinforce NR, BR and EPDM rubbers. For NR, to react the sulphur in the silane on the kaolin surface with the rubber chains and optimise the reaction between the two, 16 phr TBBS and 0.2 phr ZnO were added to the kaolin-filled rubber. The hardness and Young s modulus increased and compression set decreased when up to 3 phr elemental sulphur was included in the kaolin-filled rubber with 16 phr TBBS and 0.2 phr ZnO. The tensile strength, elongation at break, stored energy density at break, and tear energy of the rubber vulcanisate reduced when elemental sulphur was added. Notably, the inclusion of elemental sulphur was the key factor in controlling the rubber properties. In an extended work, 60 phr silane pre-treated kaolin was mixed with NR, BR and EPDM and the rubbers were cured using the novel cure systems developed earlier. The effect of 140 phr kaolin on the properties of NR was also investigated. For NR, the hardness increased by 64% when 60 phr kaolin was added and the trend continued rising by another 28% when the loading of kaolin reached 140 phr. Similarly, the Young s modulus rose by 170% with 60 phr kaolin and then by an extra 148% when the full amount of kaolin, i.e. 140 phr, was reached. The tensile strength and tear energy were unchanged and the elongation at break and stored energy density at break deteriorated by a total of 65% and 34%, respectively with 140 phr kaolin. The compression set of the unfilled rubber was 41%, and it then rose to 64% and 71%, when 60 and 140 phr kaolin was added, respectively. For BR, the hardness increased by 23% and for EPDM, by 34%, respectively when 60 phr kaolin was incorporated in the rubbers. For BR, the tensile strength, elongation at break and Young s modulus rose by 759%, 256% and 114%, respectively. The compression set of the unfilled BR was 9.4%, and subsequently rose to 26% when 60 phr kaolin was mixed with the rubber. For EPDM, the tensile strength, elongation at break and Young s modulus improved by 964%, 332% and 71%, respectively. For BR, the stored energy density at break and tear energy were increased by 2442% and 536%, respectively and for EPDM, by 3133% and 1479%, respectively. The compression set of the unfilled EPDM was 39%, and afterward increased to 48% with 60 phr kaolin. Kaolin was found to be extending or non-reinforcing filler for the strain-induced crystallising NR and highly reinforcing for the non-crystallising BR and EPDM.

Made available in DSpace on 2014-10-09T12:40:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:25Z (GMT). No. of bitstreams: 1 02754.pdf: 4328474 bytes, checksum: 6fdb5d10397ad0fb34056831c731e939 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016. / This dissertation presents how material properties (solids densities, particle size distributions, particle shapes and concentration) of gold tailings slurries are related to their rheological parameters, which are yield stress and viscosity. In this particular case Bingham yield stresses and Bingham plastic viscosities. Predictive models were developed from analysing data in a slurry database to predict the Bingham yield stresses and Bingham plastic viscosities from their material properties. The overall goal of this study was to develop a validated set of mathematical models to predict Bingham yield stresses and Bingham plastic viscosities from their material properties. The interaction of the non-Newtonian material properties is very complex at varying mass solids concentrations. The evaluation of these interactions in terms of constitutive equations is almost impossible and the relationship between material properties, mass solids concentration and rheology can only be modelled in a statistical manner. The validity of each model is checked to ensure that predictions and interpretations are unbiased and efficient. This is done by comparing the resulting models to experimental data generated from test work. An in-depth analysis was conducted to see the interrelationship between the material properties and how they affect the yield stress and viscosity values.

Orientador: Rubens Maciel Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T16:48:21Z (GMT). No. of bitstreams: 1 Morales_SergioAndresVillalba_M.pdf: 2097628 bytes, checksum: 79c13cea8a3699c3adc3ce9d027be6e1 (MD5) Previous issue date: 2011 / Resumo: Na presente dissertação foi avaliado o uso de radiação infravermelha, produzida por um laser de CO2, na viscorredução de frações pesadas do petróleo, sendo uma tecnologia inédita na literatura. O principal critério utilizado para a avaliação da tecnologia foi comparar as viscosidades dos resíduos da destilação atmosférica antes e depois de serem irradiados sob diferentes condições operacionais do laser. Para estabelecer um perfil adequado de comparação foi realizado um amplo estudo reológico destes materiais usando-se de um reômetro de placas paralelas. Caracterizações químicas e térmicas; assim como simulações numéricas do efeito térmico do laser sobre os resíduos foram também desenvolvidas para uma melhor avaliação do processo. Os resíduos atmosféricos mostraram estar constituídos por hidrocarbonetos na faixa dos C20 a C110 e de alto grau de aromaticidade; sendo 5% da sua composição correspondente a hidrocarbonetos asfalténicos. Esta composição fez com que o comportamento newtoniano fosse obtido a temperaturas de 100 °C, para o resíduo mais pesado, e 90 ºC para o menos pesado, apresentando a estas temperaturas viscosidades de 1200 e 500 cP, respectivamente. As irradiações com o laser em modo automático permitiram reduzir estes valores em até 13%; enquanto que as irradiações em modo manual produziram o efeito contrário devido à excessiva liberação de gases. Finalmente, a simulação com o software ANSYS CFX 11.0 demonstrou a alta sensibilidade da temperatura da amostra quando realizadas pequenas modificações nos parâmetros operacionais do laser assim como o pequeno volume de amostra capaz de atingir a temperatura de craqueamento durante a irradiação. / Abstract: The use of infrared radiation produced by a CO2 laser in visbreaking of heavy fractions of petroleum was assessed. The main criterion used to evaluate the technology was to compare the viscosities of atmospheric distillation residues before and after being irradiated under different operating conditions of the laser. A suitable profile for comparison was developed through a large rheological study of the materials by using a parallel plate rheometer. Chemical and thermal characterizations, as well as numerical simulations of the thermal effect of laser on the atmospheric residues were also developed aiming a better evaluation of the process. The atmospheric residua analyzed shown to be composed by hydrocarbons with carbon chains ranging from C20 to C110 and a high degree of aromaticity, corresponding the 5% of its composition to asphaltenic hydrocarbons. The Newtonian behavior was obtained at temperatures of 100 ° C, for the heavier residue, and 90 ° C for the lightest one, showing viscosities of 1200 and 500 cP, at these temperatures, respectively. The irradiations with the laser in automatic mode led to a reduction of these figures by 13%, while in manual mode, the radiation produced the opposite effect due to excessive release of gases. Finally, the simulation with ANSYS CFX 11.0 demonstrated the high sensitivity of the sample temperature when carried out minor modifications to the operating parameters of the laser as well as the small sample volume that attains the cracking temperature during irradiation. / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química