Fourier transform ir studies of the degradation of polyacrylonitrile copolymers—I

Coleman, Michael M.; Sivy, G.T.

doi:10.1016/0008-6223(81)90118-4

Cited by 94 publications

(38 citation statements)

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“…Those new bands were ascribable to C=C stretching, C=N stretching, and C=C-H bending. [8] These observations strongly suggest that dehydrogenation and cyclization occur in the course of the calcination, resulting in the ladder structure as illustrated in Scheme 1. PAN-C200-AO600.…”

Section: Resultsmentioning

confidence: 93%

“…, and C-C (1237 cm −1 ) groups. [8] After the calcination (Fig. 4b), the intensities of these bands were largely decreased and new absorption bands appeared at 1674, 1632, and 809 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

“…[7] Scheme 1 represents the possible chemical reactions in the course of the oxidative stabilization and carbonization steps. [7,8] In the first step, PAN is calcined in air at few hundreds °C. This changes PAN to carbon in the ladder structure via oxidation, dehydrogenation, and cyclization.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of Nitrogen‐Doped Carbon from Polyacrylonitrile and its Application as a Solid‐Base Catalyst

et al. 2015

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N-doped carbon (N-carbon) materials were prepared from a commercial polyacrylonitrile (PAN) by calcination and subsequent ammoxidation and these were used for a model reaction of Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. The catalytic activity of the calcined PAN for the reaction was very low, but it was greatly enhanced by the ammoxidation and the enhancement depended on both the calcination and ammoxidation temperatures. X-ray photoelectron spectra indicated the presence of pyridine-type and pyrrole-/pyridone-type N species and the amount of the former N species was well correlated with the catalytic activity. It was suggested that the presence of pyridine-type N in the graphene structure is significant for the emergence of the catalytic activity. The most active N-carbon catalyst prepared in the present study was much more active than solid base catalysts reported so far including N-carbon derived from activated carbon, N-doped carbon nanotubes, and a few metal oxide based catalysts.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

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Preparation of Nitrogen‐Doped Carbon from Polyacrylonitrile and its Application as a Solid‐Base Catalyst

et al. 2015

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“…As shown in Fig. 3, the cyclization of nitrile groups yields an imine structure, which then probably tautomerizes to an enamine structure [23]. Thus, the 1595cm -1 band has been generally assigned to the combination vibrations of C=N and C=C stretching, and NH in-plane bending [24].…”

Section: Sample Codementioning

confidence: 99%

FTIR Study of the retardation effect of boric acid on the cyclization reaction of polyacrylonitrile

et al. 2009

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A retardation effect of boric acid on the cyclization reaction of polyacrylonitrile (PAN) was clearly observed by Fourier transform infrared spectroscopy. The Lewis acid nature of boric acid probably accounts for this retardation effect. A quantitative evaluation of this effect was also made, indicating two potential applications, i.e., high temperature stabilization and melt spinning, which are favourable for the cheap and fast fabrication of PAN-based carbon fibers.

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“…Essa etapa ocorre geralmente entre 180 a 300 °C em atmosfera que contenha oxigênio [8,11] . Coleman et al [12][13][14][15] propuseram que a degradação térmica da PAN sob vácuo inicia-se próximo a 160 °C. Masson [16] atribui que a degradação térmica da PAN é conseqüência de sua natureza altamente polar.…”

Section: Introductionunclassified

Análise térmica da poliacrilonitrila plastificada com glicerol em extrusora

Júnior¹,

Fleming²,

Pardini³

et al. 2012

Polímeros

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Resumo: Neste trabalho são apresentados resultados de análise térmica para poliacrilonitrila (PAN) plastificada com glicerina. Foram observados os efeitos da glicerina de alta pureza (glicerol) e demais aditivos à base de glicóis na fusão e degradação térmica da PAN pela técnica de DSC sob alta taxa de aquecimento (90 °C/min) e atmosfera inerte. Foi constatado que o glicerol reduziu a temperatura de fusão da PAN de 290 °C para 217 °C. Em uma etapa preliminar foi empregado o método de Kissinger para verificar o efeito da composição química da PAN sob sua degradação térmica. A energia de ativação aparente para o copolímero de PAN foi calculada em 149 kJ.mol -1 . Sugeriu-se que a presença do comonômero acetato de vinila (AV) na composição química da PAN proporcionou menor entalpia de degradação (353 J.g -1 ) em comparação com outros comonômeros constituintes de uma PAN precursora de fibras de carbono (988 J.g -1 ). Palavras-chave: Poliacrilonitrila, glicerina, análise térmica, método de Kissinger. Thermal Analysis of Extruded Polyacrylonitrile Plasticized by GlycerolAbstract: This paper presents results from thermal analysis of polyacrylonitrile (PAN) plasticized with glycerin, where effects from the high purity glycerin (glycerol) and other additives to glycol were studied. Using differential scanning calorimetry (DSC) at high heating rate (90 °C/min) and inert atmosphere, we observed a decrease in the melting temperature of PAN (from 290 °C to 217 °C) owing to the presence of glycerol. The Kissinger's method was used to investigate the kinetics of thermal degradation for acrylonitrile (AN) with vinyl acetate (AV). The apparent activation energy for the copolymer AN/AV was calculated as 149 kJ.mol -1 . The AV comonomer resulted in a lower degradation enthalpy for the copolymer AN/AV (353 J.g -1 ) compared with the comonomers comprising a precursor PAN for carbon fibers (988 J.g -1 ). Keywords: Polyacrylonitrile, glycerin, thermal analysis, Kissinger's method. IntroduçãoA poliacrilonitrila (PAN) é um copolímero sintético, sintetizado preferencialmente via polimerização radicalar a partir do monômero acrilonitrila AN (C 3 H 3 N). A inserção de comonômeros dando origem a copolímeros de PAN podem resultar materiais com novas propriedades, permitindo assim a modificação das propriedades da PAN tanto pelo tipo de comonômero como pela sua quantidade em relação ao monômero AN. Comonômeros ácidos (ácido itacônico (IA), por exemplo) aumentam a propriedade hidrofílica das fibras de PAN e reduzem a temperatura de degradação [1] . A presença de um comonômero neutro como o acetato de vinila (AV) no copolímero de PAN (Figura 1) pode aumentar a solubilidade da PAN em vários solventes orgânicos empregados em processos de fiação da solução [2,3] .Sob aquecimento gradual, antes de atingir a temperatura de fusão (entre 320 a 330 °C), ocorre a ciclização dos grupos nitrilas adjacentes na cadeia molecular e subseqüentemente a degradação do polímero PAN [4,5] . O mecanismo de degradação da PAN é complexo e há discordâncias na literatura...

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Fourier transform ir studies of the degradation of polyacrylonitrile copolymers—I

Cited by 94 publications

References 3 publications

Preparation of Nitrogen‐Doped Carbon from Polyacrylonitrile and its Application as a Solid‐Base Catalyst

Preparation of Nitrogen‐Doped Carbon from Polyacrylonitrile and its Application as a Solid‐Base Catalyst

FTIR Study of the retardation effect of boric acid on the cyclization reaction of polyacrylonitrile

Análise térmica da poliacrilonitrila plastificada com glicerol em extrusora

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