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The thermal degradation of polyvinyl chloride (PVC) is a significant processing challenge which can lead to deleterious mechanical and optical properties in a wide range of products. Synergetic studies on PVC model compounds and blends of bulk PVC provide unique insights into the thermal degradation and stabilization pathways in the presence of common additives. Model PVC compounds were selected to replicate specific defects (e.g., allylic, vicinal and tertiary) and tacticity (i.e., utilizing stereochemistry to investigate tacticity) commonly found in PVC. Model studies were conducted neat (solvent-free) with metal carboxylates. Experimental results highlight that the allylic and tertiary defects are more reactive than pristine PVC and isotactic sites are more reactive than their syndiotactic counterparts. Zinc stearate was found to act not in the role of substituent, but as a Lewis acid by facilitating dehydrochlorination of labile chlorides. This prevents the accumulation of hydrogen chloride and autocatalytic chain unzipping. In contrast, calcium stearate delayed the formation of zinc chloride, a much stronger Lewis acid than zinc stearate, through an ion exchange process to form calcium chloride. Thermal weight loss studies using blends of bulk PVC proved critical in transferring mechanistic insights into the context of a polymeric matrix. Post-combustion carbon capture has traditionally involved the use of aqueous alkanol amine solutions. The regeneration of such systems, however, can be costly and energy intensive. We have developed an alternative system utilizing silylated alkylamines to reversibly capture CO2 under near ambient conditions. The silyl amines developed capture CO2 through chemical reaction to form reversible ionic liquids (RevIL). RevILs utilize no added water and are tunable by molecular design allowing us to influence industrially relevant carbon capture properties such as viscosity, temperature of reversal, and enthalpy of regeneration, while maximizing overall CO2 capture capacity. We demonstrate a strong structure-property relationship among the silyl amines where minor structural modifications lead to significant changes in the bulk properties of the RevIL. Amine containing substrates are important building blocks for a variety of biological and pharmaceutical compounds. However, application of the otherwise versatile Suzuki reaction to these substrates has proved challenging due to either ligation of the amine to the palladium or to electronic effects slowing the oxidative addition step. Conventional methods to overcome these challenges involve protection-deprotection strategies or the use of designer ligands to facilitate reaction. We have shown that application of CO2 pressure and adjusting the water content of the reaction system facilitate the Suzuki coupling of 4-amino-2-halopyridines in high yield with the simple Pd(TPP)2Cl2 catalyst. The protocol was expanded to 2-halopyridines. The results of these investigations will be discussed.

Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2013-04-10T16:31:48Z No. of bitstreams: 7 Marco 7.pdf: 246654 bytes, checksum: 0c5bf1d74df6ac0106a9cc8e1b18f21b (MD5) Marco 6.pdf: 1364038 bytes, checksum: 3b97a39e5bccbc78500a4c0afe8ac4fe (MD5) Marco 5.pdf: 1812363 bytes, checksum: 39cf3c9bb270b23b7d409571aad9c07f (MD5) Marco 4.pdf: 1290056 bytes, checksum: 92fadc3b1b5573893370bcf57e288326 (MD5) Marco 3.pdf: 1880966 bytes, checksum: ec424670898075ed2a402f4311c7ca2c (MD5) Marco 2.pdf: 545170 bytes, checksum: 798a1ca95b5a37fec7871bf3a5de5df5 (MD5) Marco 1.pdf: 564901 bytes, checksum: 4011e434981588d4b4b2a9e531286a8e (MD5) / Approved for entry into archive by Rodrigo Meirelles(rodrigomei@ufba.br) on 2013-04-13T20:02:46Z (GMT) No. of bitstreams: 7 Marco 7.pdf: 246654 bytes, checksum: 0c5bf1d74df6ac0106a9cc8e1b18f21b (MD5) Marco 6.pdf: 1364038 bytes, checksum: 3b97a39e5bccbc78500a4c0afe8ac4fe (MD5) Marco 5.pdf: 1812363 bytes, checksum: 39cf3c9bb270b23b7d409571aad9c07f (MD5) Marco 4.pdf: 1290056 bytes, checksum: 92fadc3b1b5573893370bcf57e288326 (MD5) Marco 3.pdf: 1880966 bytes, checksum: ec424670898075ed2a402f4311c7ca2c (MD5) Marco 2.pdf: 545170 bytes, checksum: 798a1ca95b5a37fec7871bf3a5de5df5 (MD5) Marco 1.pdf: 564901 bytes, checksum: 4011e434981588d4b4b2a9e531286a8e (MD5) / Made available in DSpace on 2013-04-13T20:02:46Z (GMT). No. of bitstreams: 7 Marco 7.pdf: 246654 bytes, checksum: 0c5bf1d74df6ac0106a9cc8e1b18f21b (MD5) Marco 6.pdf: 1364038 bytes, checksum: 3b97a39e5bccbc78500a4c0afe8ac4fe (MD5) Marco 5.pdf: 1812363 bytes, checksum: 39cf3c9bb270b23b7d409571aad9c07f (MD5) Marco 4.pdf: 1290056 bytes, checksum: 92fadc3b1b5573893370bcf57e288326 (MD5) Marco 3.pdf: 1880966 bytes, checksum: ec424670898075ed2a402f4311c7ca2c (MD5) Marco 2.pdf: 545170 bytes, checksum: 798a1ca95b5a37fec7871bf3a5de5df5 (MD5) Marco 1.pdf: 564901 bytes, checksum: 4011e434981588d4b4b2a9e531286a8e (MD5) Previous issue date: 2006 / A pesquisa aqui apresentada teve como objetivo principal avaliar as propriedades mecânicas (resistência à tração, impacto e dureza) de compósitos produzidos com materiais residuais da indústria, constituídos por fase matriz de PVC reciclado e fase dispersa com frações volumétricas de 5, 10 e 20 % tanto de fibras de nylon 6 quanto de fibras de sisal. Objetivou, também, determinar em que medida o reforço de fibras curtas e orientadas aleatoriamente, poderia recuperar no PVC reciclado, as propriedades originais do PVC. Isto porque, sabe-se que os polímeros termoplásticos quando submetidos a processos de reciclagem tendem a apresentar perda nos valores de propriedades mecânicas, em virtude de rompimento de ligações entre suas cadeias moleculares. A pesquisa, ao usar materiais, resíduos e rejeitos industriais, notadamente o PVC e o sisal, visando futuro aproveitamento em novos materiais de construção, contribui não só para minimizar o impacto negativo do descarte de tais materiais nos resíduos sólidos urbanos, mas, também, para a busca do desenvolvimento sustentável. Apresenta revisão bibliográfica sobre pesquisas realizadas com compósitos similares além dos métodos seguidos para a produção e caracterização física e química dos compósitos, produzidos através de moldagem por injeção, e os procedimentos para realização dos ensaios mecânicos de tração direta, de impacto e de dureza. O PVC reciclado utilizado foi resultante de moagem e posterior pulverização de conexões produzidas com a mesma matéria prima utilizada para o PVC original As fibras de sisal, com comprimento médio de 3,5 cm, foram utilizadas nos compósitos, sem nenhum prévio tratamento térmico ou químico. As fibras de nylon, com comprimento médio de 2,5 cm, sendo rejeitos industriais, já possuíam um revestimento com um composto à base de látex, formaldeido e resorcinol. Os principais resultados da pesquisa foram: (i) o PVC reciclado teve desempenho mecânico semelhante ao do PVC original, em virtude de não ter passado por processo de envelhecimento acelerado, ou seja, praticamente manteve a mesma estrutura molecular do PVC original; (ii) entre as fibras, o sisal apresentou melhor desempenho que o nylon em todas as situações estudadas, pois além do seu módulo de elasticidade ser bastante superior que o do nylon 6, demonstrou ter havido, nas suas formulações, melhores coeficiente de forma e aderência na interface matriz-fibra. / Salvador

This study investigates the use of polyvinyl chloride (PVC) as a partial substitute of natural aggregates in concrete as fine and coarse aggregates. Concrete was prepared by replacing natural aggregates with equal volume of grinded PVC, with volume replacement ratio as 10%, 50% for fine and then 10% and 50% for coarse aggregates. Experiments were performed to investigate the wet density, workability (measured by slump test), compressive strength, elastic modulus, and water absorption of concrete. After checking the particle distribution (sieve analysis), wet density, workability, and compressive strength, since compressive strength of coarse PVC concrete was much less than that of the reference concrete it was decided to continue the investigation using only the fine partial replacements. The results showed that the wet density of concrete gradually decreased with the increase of PVC content, and workability increased with the increase of PVC. Compressive strength decreased by 13 to 20% for fine PVC and 25 to 31% for coarse PVC concrete, as PVC content increased. Also, it was realized that with the increase of PVC content, elastic modulus decreased by 8.7% for 10% fine PVC while 30% for 50% coarse PVC concrete, and water absorption decreased by 27% for 10% fine PVC concrete and 36% for the 50% fine PVC. It is not advisable to replace aggregates with PVC for achieving reference strength of 40 MPa with water to cement ratio. After studying many probabilities of using the PVC aggregates, it was decided to work on the possible maximum and minimum percentages of substitution, where it was chosen to be 10 and 50%.

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