Three systems of electrospun composite membranes with piezoelectric polymer polyvinylidene fluoride (PVDF) as matrix incorporating: 1) Carbon based fillers: carbon nanotube (CNT) and graphene oxide (GO); 2) Ceramic based fillers-barium titanate (BT), zinc oxide (ZnO) and nanoclays (halloysite and bentonite); 3) Cellulosic fillers: microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) at different loadings were prepared by electrospinning process. Influence of filler type and loading on total PVDF crystallinity (Xc), relative fraction of β phase (piezoelectric phase) in total crystalline PVDF (Fβ), volume fraction of β phase in the samples (vβ) and piezoelectric coefficient d33 were characterised and analysed. Correlation between vβ and piezoelectric performance (d33) will be focused by this work. A common situation was observed for the composites-d33 increased while vβ is reduced by the fillers, so it can be concluded that d33 of the composites is not totally up to their vβ, there are other factors that need to be taken into account. For example, for carbon based filler like CNT, it increased electric conductivity of sample during and after electrospinning process, making it easier for charges produced by β crystals from inside of sample to be transferred to surfaces of the sample, and possibly promoting orientation of β crystals in d33 direction, therefore enhanced d33 of the composites though β phase formation was significantly hindered by inclusion of CNT; For piezoelectric ceramic fillers like BT and ZnO, a possible combined piezoelectricity from filler and β phase PVDF might enhanced d33 though less β phase was formed; And for non-piezoelectric and non-conductive fillers, enhancement in orientation of β crystals might play a major role in promotion of d33. Keywords: electrospinning; polyvinylidene fluoride (PVDF); nanocomposites; piezoelectric coefficient d33; energy harvesting.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-04T12:51:42Z No. of bitstreams: 1 2011 - Samantha Grisol da Cruz.pdf: 738384 bytes, checksum: 51b03e05eacc0b118f5eef0fd1f9c373 (MD5) / Made available in DSpace on 2016-10-04T12:51:42Z (GMT). No. of bitstreams: 1 2011 - Samantha Grisol da Cruz.pdf: 738384 bytes, checksum: 51b03e05eacc0b118f5eef0fd1f9c373 (MD5) Previous issue date: 2011-02-02 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Environmental pollution caused by heavy metals from different economic activities, including the oil wells drilling has been one source of soil contamination by lead, barium and zinc. These metals compose substances such as barita and galena, which are used to density control of drilling fluid. The soil remediation frequently uses EDTA (1.0 M) as extractor agent, which generates a large amount of concentrated liquid metals. The metals present in this aqueous solution are present at low concentrations (between 10-7 and 10-4 mols.dm-3), which can?t be removed by traditional methods. Alternatively, flotation treatment is a technique that has a viable capacity to handle large volumes of effluent in relatively small areas and accepts combinations with other techniques such as coagulation. This study aimed to verify the removal efficiency of Pb, Zn and Ba present in a synthesized solution, which simulates the effluent generated by contaminated soil washing, by dispersed air flotation. The experiments were conducted at bench scale and have been investigated the influence of the parameters involved in the process, such as pH, flotation time, column height and bubble size. All the study was done by colloid flotation using ferric chloride as coagulant and sodium dodecyl sulfate as the collector of a stoichiometric ratio of three sodium dodecyl sulfate to one of metal. The results showed that the technique has produced satisfactory results in the removal of lead, barium and zinc reached up to 100% removal of the metal, making it possible to meet criteria and standards for effluent discharge described in the RESOLUTION N?. 357, THE NATIONAL COUNCIL ON THE ENVIRONMENT (CONAMA). / A polui??o ambiental por metais pesados resulta de diferentes atividades econ?micas, entre elas, a perfura??o de po?os de petr?leo tem sido uma das fontes de contamina??o do solo por Chumbo, B?rio e Zinco. Estes metais s?o provenientes de subst?ncias como a barita e a galena que s?o utilizadas para o controle da densidade de fluido de perfura??o. Para remedia??o deste solo ? feito uma lavagem com EDTA (1,0M), de onde ser? gerado um volume de l?quido concentrado dos metais antes presentes no solo. Os metais presentes nesta solu??o aquosa encontram-se em concentra??es reduzidas (entre 10-7 e 10-4 mol.dm-3), o que dificulta resultados satisfat?rios ao utilizar m?todos tradicionais. Como alternativa de tratamento a flota??o ? uma t?cnica que possui uma capacidade vi?vel de tratar grandes volumes de efluentes em ?reas relativamente pequenas e que aceita combina??es com outras t?cnicas, como a coagula??o. O presente trabalho teve por objetivo verificar a efici?ncia de remo??o dos metais Pb, Ba e Zn presentes em uma solu??o sintetizada, que simula o efluente gerado na lavagem do solo contaminado, via flota??o por ar disperso. Os experimentos foram realizados em escala de bancada e nestes foram investigados a influ?ncia dos par?metros envolvidos no processo. Tais como: pH, tempo de flota??o, Altura da coluna e tamanho de bolha. Todo o estudo foi feito por flota??o de col?ides, usando o cloreto f?rrico como agente coagulante e o dodecil sulfato de s?dio como coletor a uma raz?o estequiom?trica de tr?s de dodecil sulfato de s?dio para um de metal. Os resultados obtidos mostraram que a t?cnica produziu resultados satisfat?rios na remo??o de chumbo, b?rio e zinco atingido at? 100% de remo??o do metal, sendo assim poss?vel atender aos crit?rios e padr?es de lan?amento de efluentes descritos na RESOLU??O NO. 357, DO CONSELHO NACIONAL DO MEIO AMBIENTE (CONAMA).