Nanocompósitos de poliuretana termoplástica e nanotubos de carbono de paredes múltiplas para dissipação eletrostática

Lavall, Rodrigo L.; Sales, J.A. de; Borges, Raquel S.; Calado, Hállen Daniel Rezende; Machado, Juliana Costa; Windmöller, Dario; Silva, Glaura G.; Lacerda, Rodrigo G.; Ladeira, Luiz Orlando

doi:10.1590/s0100-40422010000100025

Cited by 11 publications

(13 citation statements)

References 25 publications

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“…The chemical structure of TPU was investigated by 1H and 13C Nuclear Magnetic Resonance (not shown) and confirmed to be composed mainly of 4,4-diphenylmethane diisocianate (MDI) and poly(tetramethyleneglycol). The content of hard segment was also evaluated by the NMR analyses as being between 14-20 mass% [25] . The short thin MWCNTs, produced by the catalytic carbon vapor deposition (CCVD) process, were provided by Nanocyl with metal residue less than 5 mass%, which was confirmed by thermogravimetric (TG) analysis (Figure 1c).…”

Section: Methodsmentioning

confidence: 99%

Electrical conductivity and thermal properties of functionalized carbon nanotubes/polyurethane composites

Lima¹,

Castro²,

Borges³

et al. 2012

Polímeros

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Multi-walled carbon nanotubes (MWCNTs) functionalized with amine and carboxyl groups were used to prepare polyurethane/ MWCNT nanocomposites in two distinct concentrations: a lower value of 1 mass% (spray coating) and a higher one of ~50 mass% (buckypaper based). The MWCNT-NH 2 sample contained only 0.5 mass% of amine groups, whereas MWCNT-COOH contained 5 mass% of carboxyl groups. The MWCNT functionalized with low amine group content showed improved thermal properties when compared to neat thermoplastic polyurethane (TPU) and MWCNT-COOH based nanocomposites. The electrical conductivity of the polyurethane elastomer was greatly increased from 10 -12 to ~10 -5 S cm -1 in the 1 mass% nanotube composite and to 7 S cm -1 for the MWCNT-NH 2 buckypaper-based nanocomposite. Furthermore, the relative high content of functional groups in the MWCNT-COOH sample, which disrupt the sp 2 structure in the nanotube walls, led to inferior properties; for instance the conductivity of the buckypaper based composite is one order of magnitude lower when using MWCNT-COOH in comparison with the MWCNT-NH 2 . These results show the range of property design possibilities available with the elastomeric polyurethane nanocomposite by tailoring the functional group content and the carbon nanotube load.

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Section: Methodsmentioning

confidence: 99%

Electrical conductivity and thermal properties of functionalized carbon nanotubes/polyurethane composites

Lima¹,

Castro²,

Borges³

et al. 2012

Polímeros

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“…As imagens das Figura 3c, d exibem MWCNTs curvados e entrelaçados na matriz polimérica, ligando "pontos" da superfície fraturada. Essa morfologia, verificada em outros compósitos nanotubo:PUs (termorrígido ou termoplástico), é essencial para a transferência de tensão entre os CNTs e a matriz quando o material é sujeito a uma solicitação mecânica [15,27] . Como evidência do recobrimento pelo polímero, o diâmetro dos nanotubos de carbono visíveis nas imagens é da ordem de 23 nm a 34,0 nm nos compósitos com MWCNTs não modificados e de 12,0 nm a 36,0 nm nos compósitos com MWCNTs modificados.…”

Section: Caracterização Dos Nanocompósitosunclassified

“…Os nanocompósitos obtidos neste trabalho foram estudados por espectroscopia de impedância eletroquímica e a condutividade elétrica foi obtida com o emprego da Equação 1 [27,39] .…”

Section: Caracterização Dos Nanocompósitosunclassified

“…No entanto, esses valores ainda são menores que usualmente obtidos considerando-se a alta condutividade dos nanotubos de carbono isolados [40,41] . Segundo Lavall e colaboradores, dependendo da adesão do polímero aos CNTs, há formação de uma camada isolante em torno destas partículas condutoras, diminuindo o contato entre os tubos e, em consequência, as propriedades de condução elétrica [27] . A condutividade de nanocompósitos do tipo polímero/CNTs depende intrinsecamente dessa relação polímero/nanotubo e é sempre menor do que a condutividade obtida pelo contato direto entre os tubos [42] .…”

Section: Caracterização Dos Nanocompósitosunclassified

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Otimização do processo de dispersão de nanotubos de carbono em poliuretano termorrígido

et al. 2016

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ResumoNeste trabalho foi desenvolvido um processo empregando misturador de alto cisalhamento e moinho de rolos para dispersar MWCNTs (multiwalled carbon nanotubes) puros e modificados em poliol visando a preparação de concentrados de 3% em massa. Condições otimizadas no trabalho permitiram a obtenção de suspensões com menor número e tamanho de agregados de MWCNTs. Compósitos contendo 0,5% em massa de MWCNTs foram preparados por diluição dos concentrados em poliol usando mistura mecânica seguida de cura. Resultados de microscopia indicaram que as melhores dispersões foram obtidas com os MWCNTs modificados, os quais permitiram um aumento na tensão na ruptura, no alongamento e uma melhor preservação da estabilidade térmica. Além disso, valores de condutividade elétrica sugerem que o compósito possa ser empregado para dissipação eletrostática. Dessa forma, os resultados obtidos demonstram que a modificação covalente da superfície dos MWCNTs e a utilização de estratégias eficientes de dispersão são essenciais para melhorar as propriedades finais dos nanocompósitos. Palavras-chave: dispersão de nanotubos de carbono, nanotubos de carbono modificados, propriedades mecânicas, poliuretano termorrígido elastomérico. AbstractA process employing high shear mixer and roll mill to disperse pristine and modified MWCNTs (multiwalled carbon nanotubes) in polyol was developed in order to prepare 3 wt% masterbatches. The optimum process conditions resulted in suspensions with smaller number and size of nanotube aggregates. Composites containing 0.5 wt% of MWCNTs were prepared by dilution of polyol masterbatches by simple mechanical mixing followed by cure. Microscopy data revealed better dispersion of modified carbon nanotubes in the polymer matrix, which promoted an increase in the tensile strength, elongation and a better preservation of thermal stability. Furthermore, electric conductivity values indicated that the composites can be used for electrostatic dissipation. These results demonstrate that the covalent modification of MWCNTs surface and the use of efficient dispersion strategies are essential to improve nanocomposites' final properties.

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“…Carbon nanotubes (CNTs) enjoy unique electronic, mechanical, photonic and chemical properties, [1][2][3][4][5][6] qualifying them to be used in biological and medical research. [7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

DFT Study on the Mechanistic, Energetic and Structural Aspects of Adsorption of Tirapazamine Onto Pristine and Functionalized Carbon Nanotubes

et al. 2017

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Using density functional theory, noncovalent interactions and two mechanisms of covalent functionalization of drug tirapazamine with pristine, COOH and COCl functionalized carbon nanotube (NT, NTCOOH and NTCOCl) have been investigated. Quantum molecular descriptors of noncovalent configurations were studied. It was specified that binding of drug tirapazamine with NTCOOH has more binding energy than NTCOCl and NT, so NTCOOH can act as a favorable system for tirapazamine drug delivery within biological and chemical systems (noncovalent). NTCOOH and NTCOCl can bond to the amino group of tirapazamine through OH (COOH mechanism) and Cl (COCl mechanism) groups, respectively. The activation parameters of two pathways were calculated and compared with each other. The activation parameters related to COOH mechanism are higher than those related to COCl mechanism and therefore COCl mechanism is suitable for covalent functionalization. These results could be generalized to other similar drugs.

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Nanocompósitos de poliuretana termoplástica e nanotubos de carbono de paredes múltiplas para dissipação eletrostática

Cited by 11 publications

References 25 publications

Electrical conductivity and thermal properties of functionalized carbon nanotubes/polyurethane composites

Electrical conductivity and thermal properties of functionalized carbon nanotubes/polyurethane composites

Otimização do processo de dispersão de nanotubos de carbono em poliuretano termorrígido

DFT Study on the Mechanistic, Energetic and Structural Aspects of Adsorption of Tirapazamine Onto Pristine and Functionalized Carbon Nanotubes

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