Search Results - "Basso,Nara Regina de Souza"

Publication Catalog - "Basso,Nara Regina de Souza"

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  1. 1

    Reactivity of zirconium and titanium alkoxides bidentade complexes on ethylene polymerization

    Publication
    by Basso, Nara Regina de Souza
    Other Authors: Greco, Paula P.; Carone, Carlos L. P.; Livotto, Paolo R.; Simplício, Lílian M. T.; Rocha, Zênis N. da et al.
    Origin: Oasisbr
    Texto completo: acesso restrito. p. 129-136
    2014 article Brazil open access
  2. 2

    Cashew nut shell liquid, a valuable raw material for generating semiconductive polyaniline nanofibers

    Publication
    by Gonçalves,Raiane Valenti
    Other Authors: Zanini,Mara Lise; Malmonge,José Antonio; Bonnaud,Leila; Basso,Nara Regina de Souza
    Origin: Oasisbr
    Abstract Cashew nut shell liquid (CNSL) is an abundant and renewable by-product of the cashew nut industry. It appears to be a valuable raw material for generating semiconductive polyaniline (PAni) nanomaterial with enhanced thermal stability and well-defined nanofiber morphology following a polymerization dispersion process. This study confirms that CNSL acts as a soft template during PAni synthesis, leading to an improvement in the nanofiber aspect. CNSL also improves the thermal stability of the PAni nanomaterial. Moreover, CNSL is an effective surfactant that promotes and stabilizes the dispersion of PAni nanofibers within water, allowing the more ecofriendly preparation of PAni nanomaterial by substituting the commonly used organic solvent with aqueous media. Finally, although CNSL promotes the formation of the conductive emeraldine salt form of PAni, increasing CNSL concentrations appear to plasticize the PAni polymer, leading to reduced electrical conductivity. However, this reduction is not detrimental, and PAni nanofibers remain semiconductive even under high CNSL concentrations.
    2018 article Brazil open access
  3. 3

    Elementary charge measurement by water electrolysis

    Publication
    by Rocha Filho, João Bernardes da
    Other Authors: Salami, Marcos Alfredo; Basso, Nara Regina de Souza; Thomaz, Raquel; Borges, Regina Maria Rabello; Neto, Ricieri Andrella
    Origin: Oasisbr
    This article presents an educational technique recommended for High School students or undergraduates on Physics or Chemistry education, which allows the measurement of the elementary charge through  water  electrolysis.  The  proposed  experiment  wraps material of easy attainment, the results have sufficient precision for the    education    purposes,    and    its    realization    promotes   interdisciplinarity, since it wraps knowledge of different areas. In addition,  this  article  presents  results  obtained  by  pupils  in laboratory classrooms.
    2009 article Brazil open access
  4. 4

    Polyethylene-polyaniline Nanofiber Composites: Evaluation of Experimental Conditions of in situ Polymerization

    Publication
    by Graebin,Ana Paula
    Other Authors: Bonnaud,Leila; Persenaire,Olivier; Murariu,Oltea; Dubois,Philippe; Rocha,Zenis Novais da et al.
    Origin: Oasisbr
    The difficult processability of polyaniline (PAni) can be overcome by preparing composites with high density polyethylene (HDPE), resulting in a conducting material with improved mechanical properties. PAni nanofibers were synthesized in this research using a rapid mixing method, while HDPE/PAni composites were prepared by in situ polymerization using Cp2ZrCl2/MAO as a catalyst system. Different experimental conditions for polymerization and an electrochemical study were performed. The findings confirmed that the addition of small amounts of Pani (up to 7%) and longer impregnation (120 min) with methylaluminoxane (MAO) before polymerization are important factors contributing to increased catalytic activity. Analysis by cyclic and differential pulse voltammetry indicates that MAO reacts with the PAni in the ethylene polymerization process, and forms active species in the presence of the catalyst. Changes in catalytic activity may be due to the kinetic consumption of the active species, which become less important in the presence of PAni.
    2015 article Brazil open access
  5. 5

    Flavone complexes of Ti and Zr active in ethylene polymerization

    Publication
    by Gheno, Grasiela
    Other Authors: Basso, Nara Regina de Souza; Ceschi, Marco Antônio; Livotto, Paolo R.; Nascimento, Alanjone Azevedo; Rocha, Zênis N. da et al.
    Origin: Oasisbr
    Texto completo: acesso restrito. p. 439–449
    2014 article Brazil open access
  6. 6

    Flavone complexes of Ti and Zr active in ethylene polymerization

    Publication
    by Gheno, Grasiela
    Other Authors: Basso, Nara Regina de Souza; Ceschi, Marco Antônio; Livotto, Paolo R.; Nascimento, Alanjone Azevedo; Rocha, Zênis N. da et al.
    Origin: Oasisbr
    Texto completo: acesso restrito. p. 439–449
    2014 article Brazil open access
  7. 7

    A New Post-Metallocene-Ti Catalyst with Maltolate Bidentade Ligand: an Investigation in Heterogeneous Polymerization Reactions in Different Mesoporous Supports

    Publication
    by Gheno,Grasiela
    Other Authors: Basso,Nara Regina de Souza; Livotto,Paolo Roberto; Ribeiro,Maria Rosário; Lourenço,João Paulo; Ferreira,Ana Elisa et al.
    Origin: Oasisbr
    A new titanium catalyst easily synthesized from ethylmaltol bidentate chelator ligand was studied in homogeneous and heterogeneous ethylene polymerization. The dichlorobis(3-hydroxy-2-ethyl-4-pyrone)titanium(IV) complex was characterized by 1H and 13C NMR (nuclear magnetic resonance), UV-Vis and elemental analysis. Theoretical study by density functional theory (DFT) showed that the complex chlorines exhibit cis configuration, which is important for the activity in olefin polymerization. The complex was supported by two methods, direct impregnation or methylaluminoxane (MAO) pre-treatment, in five mesoporous supports: MCM-41 (micro and nano), SBA-15 and also the corresponding modified Al species. All the catalytic systems were active in ethylene polymerization and the catalytic activity was strongly influenced by the method of immobilization of the catalyst and the type of support.
    2016 article Brazil open access
  8. 8

    Few Layer Reduced Graphene Oxide: Evaluation of the Best Experimental Conditions for Easy Production

    Publication
    by Pavoski,Giovani
    Other Authors: Maraschin,Thuany; Fim,Fabiana de Carvalho; Balzaretti,Naira Maria; Galland,Griselda Barrera; Moura,Cássio Stein et al.
    Origin: Oasisbr
    This work aimed to produce graphene oxide with few graphene layers, a low number of defects, good conductivity and reasonable amount of oxygen, adequate for use as filler in polymeric composites. Two starting materials were evaluated: expanded graphite and graphite flakes. The method of oxidation used was the Staudenmaier one, which was tested over different lengths of time. No appreciable differences were found among the oxidation times and so the lowest oxidation time (24 h) was chosen as the most adequate. An investigation was also conducted into suitable temperatures for the reduction of graphite oxide. A temperature of 1000 ºC gave the best results, allowing a good quality material with few defects to be obtained. The reduction was also evaluated under inert and normal atmosphere. The best results were obtained when the least modified material, e. g., graphite flakes, was used as a starting material, oxidized for 24h and reduced at 1000 ºC for 30 s in a quartz ampoule under a normal atmosphere.
    2017 article Brazil open access
  9. 9

    A new post-metallocene-ti catalyst with maltolate bidentade ligand: an investigation in heterogeneous polymerization reactions in different mesoporous supports

    Publication
    by Gheno, Grasiela
    Other Authors: Basso, Nara Regina de Souza; Livotto, Paolo Roberto; Ribeiro, Maria Rosário; Lourenço, J. P.; Ferreira, Ana Elisa et al.
    A new titanium catalyst easily synthesized from ethylmaltol bidentate chelator ligand was studied in homogeneous and heterogeneous ethylene polymerization. The dichlorobis(3-hydroxy-2-ethyl-4-pyrone)titanium(IV) complex was characterized by 1H and 13C NMR (nuclear magnetic resonance), UV-Vis and elemental analysis. Theoretical study by density functional theory (DFT) showed that the complex chlorines exhibit cis configuration, which is important for the activity in olefin polymerization. The complex was supported by two methods, direct impregnation or methylaluminoxane (MAO) pre-treatment, in five mesoporous supports: MCM-41 (micro and nano), SBA-15 and also the corresponding modified Al species. All the catalytic systems were active in ethylene polymerization and the catalytic activity was strongly influenced by the method of immobilization of the catalyst and the type of support.
    2016 article Portugal open access
  10. 10

    Synthesis of a new zirconium catalyst for ethylene polymerization

    Publication
    by Fim, Fabiana de C.
    Other Authors: Machado, Tiago; Sá, Denise Santos de; Livotto, Paolo R.; Rocha, Zênis N. da; Basso, Nara Regina de Souza et al.
    Origin: Oasisbr
    Texto complete: acesso restrito. p. 3830-3841
    2013 article Brazil open access