Video summarizing Ph.D. dissertation for a non-specialist audience. / National Science Foundatio (Grant No. 0846861) / Civil and Environmental Engineering / College of Engineering

Orientador: José Antonio Malmonge / Banca: Darcy Hiroe Fujii Kanda / Banca: Luiza de Castro Folgueras / Resumo: Compósito de Borracha Natural e polianilina dopada com o ácido dodecilbenzenosulfonico foram obtidos por meio da polimerização in situ da anilina no látex de borracha natural, utilizando o persulfato de amônio como oxidante. Compósitos foram obtidos a partir de diferentes razões em massa de Borracha Natural/Anilina (BN/AN variando de 4 a 19) e caracterizados pelo método de duas e quatro pontas, espectroscopia ultravioleta-visível (UV-Vis-NIR), calorimetria diferencial de varredura (DSC), difratometria de raios-X (DRX) e microscopia eletrônica de varredura (MEV). A condutividade do compósito aumentou com a diminuição da razão BN/AN alcançando a ordem de 10-2 S/cm (BN/AN = 4), na qual é cerca de 10 ordens de grandeza maior do que a condutividade elétrica da borracha natural. Os espectros na região UV-Vis-NIR, demonstraram que a polianilina se encontra no estado de oxidação sal esmeraldina. Os difratogramas de raios-X mostraram que a polianilina sintetizada no meio látex apresenta planos cristalinos semelhantes às amostras sintetizadas em meio aquoso. Nas micrografias de MEV observou-se que a PAni-DBSA apresenta morfologia globular com boa dispersão na matriz BN, sendo a maioria com tamanho menores que 200 nm. A transição vítrea da borracha não foi alterada com o conteúdo de PAni observado nas análise de DSC. Os compósitos ternários de borracha natural com polianilina-DBSA e ferrita de bário foram também obtidos via da polimerização in situ da anilina, em meio látex de borracha natural contendo as partículas de ferrita de bário. Um expressivo aumento na absorção de energia eletromagnética no intervalo de 8 à 12 GHz, foi observada com a medida que a quantidade de ferrita foi aumentada na matriz. Para o compósito com a razão BN/AN = 12, a medida de refletividade máxima foi de -8 dB o que... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Composites of Natural Rubber with Polyaniline doped with dodceylbenzenesulphonic acid, were obtained by in situ polymerization of aniline in natural rubber latex medium using ammonium peroxydisulfate - (NH4)2S2O8 - as oxidant. The composites were obtained for different mass ratio of Natural Rubber/Aniline (NR/AN) in the range of NR/AN = 4 to 19 and characterized by four and two probe electrical conductivity, ultraviolet-visible-near infrared spectroscopy (UV-Vis-NIR), differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. The electrical conductivity increase as NR/AN ratio decrease, reaching around 10-2 S/cm (NR/AN = 4) which is 1012 of magnitude higher than pure natural rubber. UV-Vis-NIR spectrum showed that polyaniline synthesized in latex medium is in its emeraldine salt form. The X-ray pattern showed that the polyaniline synthetized in latex medium has the same crystal planes of the synthesized in an aqueous medium. The scanning electron microscopy micrograph showed globular morphology of PAni-DBSA phase, uniformly distributed in the NR matrix with size mostly smaller than 200nm. The glass transition temperature was unaffected by the PAni amount in the NR matrix according to differential scanning calorimetry thermograms. Ternary composites of NR with PAni-DBSA and Barium Ferrite were also obtained by in situ polymerization of aniline in latex medium containing Barium Ferrite particle. Considerable increase in the reflection loss, in the range of 8 to 12 GHz, was observed increasing the amount of Barium Ferrite in the rubber matrix. For the composite NR/AN=12 the maximum reflection loss was -8 dB which correspond to 84 % of absorbed energy. Adding 20wt% of Barium Ferrite, related... (Complete abstract click electronic access below) / Mestre

Used vulcanized rubber tires have caused serious trouble worldwide. Current disposal and recycling methods all have undesirable side effects, and they generally do not produce maximum benefits. A thermocatalytic process using aluminum chloride as the main catalyst was demonstrated previously from 1992 to 1995 in our laboratory to convert used rubber tire to branched and ringed hydrocarbons. Products fell in the range of C4 to C8. Little to no gaseous products or fuel oil hydrocarbons of lower value were present. This project extended the previous experiments to accumulate laboratory data, and provide fundamental understanding of the thermocatalytic decomposition reaction of the model compounds including styrene-butadiene copolymers (SBR), butyl, and natural rubber. The liquid product yields of SBR and natural rubber consistently represented 20 to 30% of the original feedstock by weight. Generally, approximately 1 to 3% of the feedstock was converted to naphtha, while the remainder was liquefied petroleum gas. The liquid yields for butyl rubber were significantly higher than for SBR and natural rubber, generally ranging from 30 to 40% of the feedstock. Experiments were conducted to separate the catalyst from the residue by evaporation. Temperatures between 400 °C and 500 °C range are required to drive off significant amounts of catalyst. Decomposition of the catalyst also occurred in the recovery process. Reports in the literature and our observations strongly suggest that the AlCl3 forms an organometallic complex with the decomposing hydrocarbons so that it becomes integrated into the residue. Catalyst mixtures also were tested. Both AlCl3/NaCl and AlCl3/KCl mixtures had very small AlCl3 partial pressures at temperatures as high as 250 °C, unlike pure AlCl3 and AlCl3/MgCl2 mixtures. With the AlCl3/NaCl mixtures, decomposition of the rubber was observed at temperatures as low as 150 °C, although the reaction rates were considerably slower at lower temperatures. The amount of naphtha produced by the reaction also increased markedly, as did the yields of aromatics and cyclic paraffin. Recommendations are made for future research to definitively determine the economic and technical feasibility of the proposed thermocatalytic depolymerization process.

Used vulcanized rubber tires have caused serious trouble worldwide. Current disposal and recycling methods all have undesirable side effects, and they generally do not produce maximum benefits. A thermocatalytic process using aluminum chloride as the main catalyst was demonstrated previously from 1992 to 1995 in our laboratory to convert used rubber tire to branched and ringed hydrocarbons. Products fell in the range of C4 to C8. Little to no gaseous products or fuel oil hydrocarbons of lower value were present. This project extended the previous experiments to accumulate laboratory data, and provide fundamental understanding of the thermocatalytic decomposition reaction of the model compounds including styrene-butadiene copolymers (SBR), butyl, and natural rubber. The liquid product yields of SBR and natural rubber consistently represented 20 to 30% of the original feedstock by weight. Generally, approximately 1 to 3% of the feedstock was converted to naphtha, while the remainder was liquefied petroleum gas. The liquid yields for butyl rubber were significantly higher than for SBR and natural rubber, generally ranging from 30 to 40% of the feedstock. Experiments were conducted to separate the catalyst from the residue by evaporation. Temperatures between 400 °C and 500 °C range are required to drive off significant amounts of catalyst. Decomposition of the catalyst also occurred in the recovery process. Reports in the literature and our observations strongly suggest that the AlCl3 forms an organometallic complex with the decomposing hydrocarbons so that it becomes integrated into the residue. Catalyst mixtures also were tested. Both AlCl3/NaCl and AlCl3/KCl mixtures had very small AlCl3 partial pressures at temperatures as high as 250 °C, unlike pure AlCl3 and AlCl3/MgCl2 mixtures. With the AlCl3/NaCl mixtures, decomposition of the rubber was observed at temperatures as low as 150 °C, although the reaction rates were considerably slower at lower temperatures. The amount of naphtha produced by the reaction also increased markedly, as did the yields of aromatics and cyclic paraffin. Recommendations are made for future research to definitively determine the economic and technical feasibility of the proposed thermocatalytic depolymerization process.

A laboratory-scale biotrickling filter (BTF, inner size 14cm ¡Ñ 14cm ¡Ñ 120cmH, packed with fern chips to a height of 100 cm and volume of 19.6 L) was used to test the feasibility of removing odorous compounds emitted from rubber-processing operations. In addition, granule activated carbon (GAC) adsorption and permanganate solution scrubbing were also tested in order to further reduce the odor intensity of vented gas from the BTF. Results indicated that with the operation conditions of EBRT (empty bed retention time) of 20-40 s for the gas through the packed space and VOCs of 5-50 ppm (as methane) for the influent gas to the BTF, approximately 96-97% of ketones (acetone and methyl ethyl ketone) and 50% of toluene and carbon disulfide in the influent gas could be removed. However, there was no significant removal for alkanes by the BTF. The overall VOC and odor removals were both around 80% at an EBRT of 23 s. Performances of GAC adsorption of the residual chemicals in the vented gas from the BTF were better than those of permanganate solution scrubbing. The overall VOC removal by the BTF-GAC system was around 90% and the overall odor (expressed as the dilution to threshold D/T value) removal was even better than that of VOC. A test indicated that D/T were 1303, 733, and 23, respectively, for the influent, BTF effluent, and GAC effluent, and the overall efficiency for the odor removal was 98.2%. It was estimated that the cost is around NT$ 70 for treating 1,000 m3 of the teat gas by the GAC. Efforts should be made by decreasing the cost by other alternative technologies.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M. Agr. St.)--University of Queensland, Gatton, 2002. / Includes bibliographical references.

Thesis (M. Agr. St.)--University of Queensland, Gatton, 2003. / Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 16, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Laurel Wilson. Vita. Includes bibliographical references.

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