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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estudo da degrada??o de misturas polim?ricas ? base de PEBD, amido, quitosana e fibra de coco em diferentes ambientes aquosos / Study of the Degradation of polymer mixtures based on LDPE , starch, chitosan and coconut fiber in different aqueous environments

Azevedo, Laryssa Cristina Medina 23 January 2016 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-19T15:59:43Z No. of bitstreams: 1 2016 - Laryssa Cristina Medina Azevedo.pdf: 3869837 bytes, checksum: 508d4054394209403e14c50fc5d2bc4b (MD5) / Made available in DSpace on 2016-10-19T15:59:43Z (GMT). No. of bitstreams: 1 2016 - Laryssa Cristina Medina Azevedo.pdf: 3869837 bytes, checksum: 508d4054394209403e14c50fc5d2bc4b (MD5) Previous issue date: 2016-01-23 / Water quality is related to the anthropogenic impact on water resources and their availability, and this quality is regulated by the National Environmental Council - CONAMA, through resolutions 357 of 2005 and 396 of 2008, from the boundaries quality standards of water bodies. The materials of organic origin, including natural polymers have an inherent tendency to degradation. The presence of oxidizable or hydrolysable groups in the chains of these polymers, in addition to hydrophobicity and hydrophilicity characteristics and degree of conformational flexibility of the chain are factors that contribute to the biodegradation of the polymer. Water pollution by hydrocarbons, including biodegradable polymers, can be an environment conducive to the presence of potentially degrading microorganisms from a variety of recalcitrant molecules released in the middle. The combination of different types of environmental effects can cause slow or fast decay, which depends on the predominant factor or degrading agent (photochemical, thermal, chemical, hydrolysis, oxidation, biodegradation). This work was carried out an investigation into the quality of water facilities (river water - RW distilled water - DW and water with nutrients - NW) after the biodegradation of polymeric blends and composites containing low density polyethylene (LDPE), thermoplastic starch (TPS), chitosan (Ch) Coconut fiber (CF). The samples were subjected to biodegradation test water in these media for a period of fifty-two days. After the test period may be seen that mixtures of TPS/Ch and TPS/CF undergone the process of biodegradation, confirmed the almost complete loss of their mass, increased conductivity, in spite of the turbidity values and the consumed oxygen concentration, decrease in the last days of rehearsal. As expected mixtures containing LDPE (LDPE/TPS, LDPE/TPS/Ch and LDPE/TPS/CF) showed less weight loss, and lower turbidity and O2 consumption in the chemical degradation of organic matter. Comparing the results of different means water, as expected, the results conductivity and pH of the river water (RW) were higher than the values found for the water with nutrients (NW) and distilled water (DW). The turbidity values and concentration of O2 consumed in the COD for the different blends containing LDPE as shown depended on the diffusion of water in the various polymeric materials and consequently influence the first stage of biodegradation, i.e., water penetration into the material surface attack of the chemical bonds of the amorphous phase and converting long chain of biodegradable polymers into smaller pieces and eventually into soluble fragments / A qualidade da ?gua est? relacionada com o impacto antropog?nico sobre os recursos h?dricos e sua disponibilidade, e essa qualidade ? regulamentada pelo Conselho Nacional do Meio Ambiente ? CONAMA, atrav?s das resolu??es 357 de 2005 e 396 de 2008, a partir do quadro dos limites dos padr?es de qualidade dos corpos h?dricos. Os materiais de origem org?nica, incluindo pol?meros naturais t?m uma tend?ncia inerente para degrada??o. A presen?a de grupos oxid?veis ou hidrolis?veis nas cadeias desses pol?meros, al?m das caracter?sticas de hidrofilicidade e hidrofobicidade e o grau de flexibilidade conformacional da cadeia s?o fatores que contribuem para a biodegrada??o do pol?mero. A polui??o das ?guas por hidrocarbonetos, incluindo pol?meros biodegrad?veis, pode ser um ambiente prop?cio ? presen?a de microrganismos potencialmente degradadores de uma variedade de mol?culas recalcitrantes liberadas no meio. A combina??o de diferentes tipos de efeitos ambientais pode causar deteriora??o r?pida ou lenta, a qual depende do fator predominante ou do agente degradante (fotoqu?mica, t?rmica, qu?mica, hidr?lise, oxida??o, biodegrada??o). Neste trabalho foi realizada uma investiga??o da qualidade de meios h?dricos (?gua de rio ? AR, ?gua destilada ? AD e ?gua com nutrientes ? AN) ap?s o ensaio de biodegrada??o de blendas e comp?sitos polim?ricos contendo polietileno de baixa densidade (PEBD), amido termopl?stico (TPS), quitosana (Q) e fibra de coco (FC). As amostras foram submetidas ao ensaio de biodegrada??o nestes meios h?dricos pelo per?odo de cinquenta e dois dias. Ap?s o per?odo de ensaio pode-se verificar que as misturas de TPS/Q e TPS/FC sofreram o processo de biodegrada??o, confirmado pela quase total perda de suas massas, aumento da condutividade, apesar dos valores de turbidez e da concentra??o de oxig?nio consumido, diminu?rem nos ?ltimos dias de ensaio. Como esperado as misturas contendo PEBD (PEBD/TPS, PEBD/TPS/Q e PEBD/TPS/FC) apresentaram menor perda de massa, al?m de menor turbidez e consumo de O2 na degrada??o qu?mica da mat?ria org?nica. Comparando os resultados dos diferentes meios h?dricos, como j? era esperado, os resultados valores de condutividade e pH da ?gua de rio (AR) foram maiores do que os valores encontrados para a ?gua com nutrientes (AN) e ?gua destilada (AD). Os valores de turbidez e DQO, para as diferentes misturas contendo PEBD, como mostrado, dependeram da difus?o da ?gua nos diferentes materiais polim?ricos e consequentemente influenciaram na primeira fase da biodegrada??o, isto ?, penetra??o da ?gua na superf?cie do material, ataque das liga??es qu?micas da fase amorfa e convers?o das longas cadeias doe pol?meros biodegrad?veis em partes menores, e, eventualmente, em fragmentos sol?veis

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