1000 resultados para Pe riodique e lectronique (Descripteur de forme)


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Polyolefin based blends have tremendous commercial importance in view of their exceptional properties. In this study the interface of a biphasic polymer blend of PE (polyethylene) and PEO (polyethylene oxide) has been tailored to reduce the interfacial tension between the phases and to render finer morphology. This was accomplished by employing various strategies like addition of maleated PE (PE grafted maleic anhydride), immobilizing PE chains, ex situ, onto MWNTs by covalent grafting, and in situ grafting of PE chains onto MWNTs during melt processing. Multiwalled nanotubes (MWNTs) with different surface functional groups have been synthesized either a priori or were facilitated during melt mixing at higher temperature. NH2 terminated MWNTs were synthesized by grafting ethylene diamine (EDA) onto carboxyl functionalized carbon nanotubes (COOH(MWNTs) and further, was used to reactively couple with maleated PE to immobilize PE chains on the surface of MWNTs. The covalent coupling of maleated PE with NH2 terminated MWNTs was also realized in situ in the melt extruder at high temperature. Both NH2 terminated MWNTs and the in situ formed PE brush on MWNTs during melt mixing, revealed a significant improvement in the mechanical properties of the blend besides remarkably improving the dispersion of the minor phase (PEO) in the blends. Structural properties of the composites were evaluated and the tensile fractured morphology was assessed using scanning electron microscopy.

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In this study, various strategies like amine terminated GO (GO-NH2), in situ formed polyethylene grafted GO (PE-g-GO) and their combinations with maleated PE (maleic anhydride grafted PE) were adopted to reactively compatibilize blends of low density polyethylene (LDPE) and polyethylene oxide (PEO). These blends were further explored to design porous, antibacterial membranes for separation technology and the flux and the resistance across the membranes were studied systematically. It was observed that GO-NH2 led to uniform dispersion of PEO in a PE matrix and further resulted in a significant improvement in the mechanical properties of the blends when combined with maleated PE. The efficiency of various compatibilizers was further studied by monitoring the evolution of morphology as a function of the annealing time. It was observed that besides rendering uniform dispersion of PEO in PE and improving the mechanical properties, GO-NH2 further suppresses the coalescence in the blends. As the melt viscosities of the phases differ significantly, there is a gradient in the morphology as also manifested from scanning acoustic microscopy. Hence, the membranes were designed by systematically reducing the thickness of the as-pressed samples to expose the core as the active area for flux calculations. Selected membranes were also tested for their antibacterial properties by inoculating E. coli culture with the membranes and imaging at different time scales. This study opens new avenues to develop PE based cost effective anti-microbial membranes for water purification.

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In this study, various strategies like amine terminated GO (GO-NH2), in situ formed polyethylene grafted GO (PE-g-GO) and their combinations with maleated PE (maleic anhydride grafted PE) were adopted to reactively compatibilize blends of low density polyethylene (LDPE) and polyethylene oxide (PEO). These blends were further explored to design porous, antibacterial membranes for separation technology and the flux and the resistance across the membranes were studied systematically. It was observed that GO-NH2 led to uniform dispersion of PEO in a PE matrix and further resulted in a significant improvement in the mechanical properties of the blends when combined with maleated PE. The efficiency of various compatibilizers was further studied by monitoring the evolution of morphology as a function of the annealing time. It was observed that besides rendering uniform dispersion of PEO in PE and improving the mechanical properties, GO-NH2 further suppresses the coalescence in the blends. As the melt viscosities of the phases differ significantly, there is a gradient in the morphology as also manifested from scanning acoustic microscopy. Hence, the membranes were designed by systematically reducing the thickness of the as-pressed samples to expose the core as the active area for flux calculations. Selected membranes were also tested for their antibacterial properties by inoculating E. coli culture with the membranes and imaging at different time scales. This study opens new avenues to develop PE based cost effective anti-microbial membranes for water purification.

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Bilboko La Pe??a auzoko pilotalekuaren erabilerarako pilota eskola proiektua

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Este trabalho apresenta resultados de uma pesquisa realizada no IFSERTO - Instituto Federal de Educao, Cincia e Tecnologia do Serto Pernambucano a respeito das desigualdades sociais nas concepes dos professores e estudantes do PROEJA. Teve como objetivo analisar e compreender os sentidos produzidos pelos sujeitos da pesquisa sobre as desigualdades sociais e suas perspectivas de superao, considerando seu histrico e seus aspectos atuais. Foi organizado epistemologicamente numa abordagem de pesquisa qualitativa a partir do ponto de vista metodolgico do estudo de caso do tipo descritivo e analtico com entrevistas e anlise do documento Base do Programa institucionalizado pelo MEC, buscando identificar as aproximaes ou distanciamentos entre as concepes dos entrevistados com a proposta do material institucional no que diz respeito s perspectivas de superao das desigualdades no contexto da EJA. O problema da pesquisa foi formulado mediante o seguinte questionamento: Como as desigualdades sociais se apresentam nas concepes dos professores e estudantes do programa e quais suas perspectivas de superao? Para estudo do problema, procedeu-se imerso no campo emprico da pesquisa com abordagens e utilizao de um roteiro de entrevistas previamente formulado, incluiu-se a leitura flutuante do material coletado e as vozes dos entrevistados foram gravadas, transcritas, lidas e analisadas, buscando a captao do sentido atribudo pelos sujeitos a respeito das desigualdades sociais. Mediante essa trajetria, identificou-se, nas concepes dos sujeitos da pesquisa, que o trabalho se apresenta como centralidade no que se refere s manifestaes das desigualdades sociais no contexto da EJA/PROEJA, bem como suas diferentes feies na lgica do sistema capitalista no que se refere a educar para a empregabilidade atendendo s exigncias do capital. Assim, considerando que, historicamente, a EJA uma modalidade de ensino que vem sendo ofertada para sujeitos que tiveram seus percursos escolares interrompidos pela condio de trabalhadores, esse tema se configura como estudo de grande relevncia no contexto das polticas de Educao de Jovens e Adultos trabalhadores.

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O romance-folhetim, gnero que invadiu os rodaps dos jornais no sculo XIX e constituiu as bases de grandes clssicos da literatura, traz consigo marcas do melodrama, levando-o a ultrapassar os limites temporais do seu surgimento e se integrar aos recursos miditicos e performance teatral para dar origem a tramas que hoje se desenrolam diariamente na tela da televiso de milhares de telespectadores durante meses, em especial na Amrica Latina. O romance-folhetim se perpetua atravs das telenovelas, principal representante da telefico, que possui uma linguagem narrativa particular, mantendo as matrizes folhetinescas, e impondo-se como uma nova modalidade textual dentro do universo do entretenimento e da literatura industrial. Exemplo disso a narrativa de Dancin days (1978), elencada como corpus para o estudo apresentado por essa dissertao, a fim de demonstrar a linha tnue que une a telenovela ao romance-folhetim, constituindo este uma matriz para as narrativas audiovisuais

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PPPEPPPP-b-PE6511PP-b-PEPP-b-PEPP-b-PEPP-b-PENMRDSCFT-IRAFMn4-CH2-nPP-b-PEAFMPP-b-PEPP-b-PEPP-b-PEPP-b-PEPP-b-PEPP-b-PE

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PP-PEPP/HDPEEPCPP-PE-PP-PE_(200)"C~(13)NMRPP-PETEMPP-PEPP/HMWPEPP-PEPEHMWPE-SEMPP-PEHMWPEPP/HDPEPP-PEHMWPEEPC-HMWPEPP/HDPEPEHMWPEHMWPE-PP/HMWPEPP/HDPESEMPP/HDPEPP/HMWPEPP/HMWPEPP-PE

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PE(portable executable),PEPE,MD5CRC32hashAPI,,

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A method was adopted to fix a series of polymers of PE-b-PEO with different PEO/PE segments on the chains of LLDPE. Maleic anhydride (MA) reacting with hydroxyl group of PE-b-PEO (mPE-b-PEO) was used as the intermediate. The structures of intermediates and graft copolymers were approved by H-1 NMR and FTIR. XPS analysis revealed a great amount of oxygen on the surface of grafted copolymers although the end group of PEO was fixed on the LLDPE chains through MA. Thermal properties of the graft copolymers as determined by differential scanning calorimetry (DSC) showed that PE segments in the grafted monomers could promote the heterogeneous nucleation of the polymer, increase T., and crystal growth rate.

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PE-g-PB-g-MA/PA6PE-g-PB-g-PA6,TEMXPSXRDDSC,PA6,,(10/min)

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,PP b PE,1 3C NMR,DSC,FT IR

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PP/TAIC()/PESEMDDV,TAICPP/PE,