Síntese e caracterização de nanocompósitos de polianilina/nanolâminas de grafite e de borracha natural/polianilina/nanolâminas de grafite
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Data
2019-04-12
Autores
Martin, Eliza Sbrogio
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Universidade Estadual Paulista (Unesp)
Resumo
O uso de nanocargas de carbono tais como nanotubos de carbono e nanolâminas de grafite (NLG), e/ou polímeros condutores em uma matriz polimérica, tem atraído à atenção de inúmeros pesquisadores que buscam sintetizar elastômeros eletricamente condutivos com amplo potencial aplicacional como dissipadores eletrostáticos, blindagem eletromagnética, sensores piezorresistivos, etc. Nesse trabalho, foram obtidos: (1) nanocompósitos de polianilina (PAni)/NLG com razão mássica anilina (An)/NLG entre 0 e 250%, utilizando ácido clorídrico como dopante (nanocompósitos PHN), e com razão mássica anilina An/NLG entre 0 e 950%, utilizando ácido dodecilbenzeno sulfônico (DBSA) como dopante (nanocompósitos PDN); (2) Blendas de borracha natural (BN)/PAni com diferentes razões BN/An, utilizando BN in natura (blendas BNP) e borracha pré-vulcanizada (BV), blendas BVP; e (3) Nanocompósitos de BN/PAni-NLG (BNP/NLG) e BV/PAni-NLG (BVP/NLG) com diferentes razões BN/An e 15% de NLG em relação a An (relação m/m). Em todas as sínteses a polimerização da anilina foi realizada in situ. Nos nanocompósitos de PAni/NLG a polimerização da PAni ocorreu sobre a superfície lisa das NLG sendo sua morfologia e grau de intercalação nas NLG influenciados pelo tipo de dopante utilizado. A condutividade elétrica máxima obtida para os nanocompósitos foi de 627 S.cm-1 e 582 S.cm-1 para nanocompósitos PHN contendo 200% de NLG e para nanocompósitos PDN contendo 600% de NLG, respectivamente. O aumento na estabilidade térmica da PAni nos nanocompósitos PAni/NLG foi atribuído a intercalação da PAni entre as NLG e propriedades de barreira apresentadas pelas NLG. Nos nanocompósitos de BNP/NLG e BVP/NLG foi observado que a polimerização da An ocorreu tanto na matriz de borracha quanto sobre a superfície das NLG presentes. Independente da BN ser vulcanizada ou não, os nanocompósitos apresentaram um aumento na estabilidade térmica, na condutividade elétrica e na resistência mecânica em relação a BN. Tais melhorias foram atribuídas a presença de PAni sendo intensificadas pelas NLG. A condutividade elétrica máxima obtida foi de 5.10-2 S.cm-1 para o nanocompósito obtido da razão mássica BN/An igual a 4 e contendo 15% de NLG. Essa condutividade é cerca de 14 ordens de grandeza maior do que a BN.
The use of carbon nanofiller such as carbon nanotube and graphite nanosheet (GNS), and/or conductive polymers as filler to a polymer matrix, has attracted the attention of numerous researchers who seek to synthesize electrically conductive elastomers with broad application potential such as electrostatic dissipator, piezoresistive sensor and electromagnetic interference shielding . In this work were synthesized: (1) nanocomposites of polyaniline (PAni)/NLG with aniline (An)/NLG mass ratio between 0 and 250%, using hydrochloric acid as a dopant (PHN nanocomposites) and aniline An/NLG between 0 and 950%, using dodecylbenzene sulfonic acid (DBSA) as a dopant (PDN nanocomposites); (2) Natural rubber blends (BN)/PAni with different BN/An mass ratio, using BN in nature (BNP blends) and pre-vulcanized rubber BV, BVP blends; and (3) BN/PAni-NLG (BNP/NLG) and BV/PAni-NLG (BVP/NLG) nanocomposites with different BN/An mass ratios and 15% NLG with respect to An (m/m ratio). In all syntheses the polymerization of aniline was performed in situ. In the nanocomposites PAni/GNS the polymerization of PAni occurred on the GNS surface and their morphology and degree of intercalation in NLGs were influenced by the type of dopant. The higher electrical conductivity obtained for PHN and PDN composites were 627 S.cm-1 and 582 S.cm-1, respectively. The increase in the thermal stability of PAni in PAni/NLG nanocomposites was attributed to the intercalation of PAni among GNS and barrier properties presented by NLG. In the BNP/NLG and BVP/NLG nanocomposites it was observed that the polymerization of An occurred in both the rubber matrix and the surface of the NLG present. Regardless of whether BN is vulcanized or not, the nanocomposites showed an increase in thermal stability, in the electrical conductivity and mechanical resistance in relation to BN. Such improvements were attributed to the presence of PAni being intensified by NLG. The higher electrical conductivity obtained was 5.10-2 S.cm -1 for the nanocomposite obtained from the BN / An mass ratio of 4 and containing 15% of GNS. This conductivity is about 14 orders of magnitude higher than BN.
The use of carbon nanofiller such as carbon nanotube and graphite nanosheet (GNS), and/or conductive polymers as filler to a polymer matrix, has attracted the attention of numerous researchers who seek to synthesize electrically conductive elastomers with broad application potential such as electrostatic dissipator, piezoresistive sensor and electromagnetic interference shielding . In this work were synthesized: (1) nanocomposites of polyaniline (PAni)/NLG with aniline (An)/NLG mass ratio between 0 and 250%, using hydrochloric acid as a dopant (PHN nanocomposites) and aniline An/NLG between 0 and 950%, using dodecylbenzene sulfonic acid (DBSA) as a dopant (PDN nanocomposites); (2) Natural rubber blends (BN)/PAni with different BN/An mass ratio, using BN in nature (BNP blends) and pre-vulcanized rubber BV, BVP blends; and (3) BN/PAni-NLG (BNP/NLG) and BV/PAni-NLG (BVP/NLG) nanocomposites with different BN/An mass ratios and 15% NLG with respect to An (m/m ratio). In all syntheses the polymerization of aniline was performed in situ. In the nanocomposites PAni/GNS the polymerization of PAni occurred on the GNS surface and their morphology and degree of intercalation in NLGs were influenced by the type of dopant. The higher electrical conductivity obtained for PHN and PDN composites were 627 S.cm-1 and 582 S.cm-1, respectively. The increase in the thermal stability of PAni in PAni/NLG nanocomposites was attributed to the intercalation of PAni among GNS and barrier properties presented by NLG. In the BNP/NLG and BVP/NLG nanocomposites it was observed that the polymerization of An occurred in both the rubber matrix and the surface of the NLG present. Regardless of whether BN is vulcanized or not, the nanocomposites showed an increase in thermal stability, in the electrical conductivity and mechanical resistance in relation to BN. Such improvements were attributed to the presence of PAni being intensified by NLG. The higher electrical conductivity obtained was 5.10-2 S.cm -1 for the nanocomposite obtained from the BN / An mass ratio of 4 and containing 15% of GNS. This conductivity is about 14 orders of magnitude higher than BN.
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Palavras-chave
Polianilina, Nanolâminas de grafite, Borracha natural, Nanocompósito, Polyaniline, Graphite nanosheet, Natural rubber, Nanocomposite