Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis
The polymerization of acrylonitrile to polyacrylonitrile (PAN) has been studied using several solvents: N,N-dimethylformamide (DMF), hexane, toluene, water, and in bulk form (no solvent). The addition of DMF is the only case where both monomer and polymer are soluble in the solvent. Thermal analyses of the resultant products after polymerization have been performed by differential scanning calorimetry and pyrolysis–gas chromatography: mass spectrometry. The effect of the solvents employed as media for polymerization is interpreted from the results of the thermal and structural (X-ray diffraction) methods. The polymer samples obtained when using water or toluene as solvents have the greater content of amorphous components compared to the others. The amide molecules are difficult to completely eliminate in the product obtained after the polymerization reaction and even after prolonged heating at 110°C and remain occluded. DMF can be considered to exert a plasticized effect on PAN and is even capable of forming complexes by dipolar bonding. As a result of this interaction, the thermogram is quite different from the other samples studied in the present work, showing a single sharp exothermic peak. This is associated with nitrile group polymerization (cyclization) of PAN. It is deduced that the amount of heat evolved as well as the temperature interval over which it is released are influenced by the chemical processing of PAN, in particular when using DMF as solvent for both monomer and polymer. Pyrolysis of the different PAN samples revealed the release of occluded solvent molecules, mainly when using DMF, and compounds produced from the thermal degradation processes. Different types of cyclized compounds, such as pyridine derivatives and aromatic nitriles were identified. All these compounds could be derived from cyclized PAN structures which are not completely degraded by the thermal treatment of pyrolysis. Alkyldinitriles have also been tentatively identified associated with the final molecular breakdown of cyclized structures with six-member rings by pyrolysis. Valuable complementary information on the structure of the PAN samples (homopolymer) obtained using the different processing approaches involving several solvent media has been provided by pyrolysis. The present results will improve our understanding of the evolution of the structure and properties of carbon and activated carbon fibres which will enable us to establish processing strategies in order to obtain these materials under adequate and reproducible conditions.
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Elsevier
2001
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Subjects: | Acrylonitrile, Polyacrylonitrile, N,N-dimethylformamide, Pyrolysis, Cyclization, Carbon fibers, Pyridine derivatives, Solvents, Processing, |
Online Access: | http://hdl.handle.net/10261/39867 |
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dig-irnas-es-10261-398672019-09-16T12:39:02Z Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis Sánchez-Soto, Pedro José Avilés Escaño, Miguel Ángel Río Andrade, José Carlos del Ginés, J.M. Pérez-Rodríguez, José Luis Acrylonitrile Polyacrylonitrile N,N-dimethylformamide Pyrolysis Cyclization Carbon fibers Pyridine derivatives Solvents Processing The polymerization of acrylonitrile to polyacrylonitrile (PAN) has been studied using several solvents: N,N-dimethylformamide (DMF), hexane, toluene, water, and in bulk form (no solvent). The addition of DMF is the only case where both monomer and polymer are soluble in the solvent. Thermal analyses of the resultant products after polymerization have been performed by differential scanning calorimetry and pyrolysis–gas chromatography: mass spectrometry. The effect of the solvents employed as media for polymerization is interpreted from the results of the thermal and structural (X-ray diffraction) methods. The polymer samples obtained when using water or toluene as solvents have the greater content of amorphous components compared to the others. The amide molecules are difficult to completely eliminate in the product obtained after the polymerization reaction and even after prolonged heating at 110°C and remain occluded. DMF can be considered to exert a plasticized effect on PAN and is even capable of forming complexes by dipolar bonding. As a result of this interaction, the thermogram is quite different from the other samples studied in the present work, showing a single sharp exothermic peak. This is associated with nitrile group polymerization (cyclization) of PAN. It is deduced that the amount of heat evolved as well as the temperature interval over which it is released are influenced by the chemical processing of PAN, in particular when using DMF as solvent for both monomer and polymer. Pyrolysis of the different PAN samples revealed the release of occluded solvent molecules, mainly when using DMF, and compounds produced from the thermal degradation processes. Different types of cyclized compounds, such as pyridine derivatives and aromatic nitriles were identified. All these compounds could be derived from cyclized PAN structures which are not completely degraded by the thermal treatment of pyrolysis. Alkyldinitriles have also been tentatively identified associated with the final molecular breakdown of cyclized structures with six-member rings by pyrolysis. Valuable complementary information on the structure of the PAN samples (homopolymer) obtained using the different processing approaches involving several solvent media has been provided by pyrolysis. The present results will improve our understanding of the evolution of the structure and properties of carbon and activated carbon fibres which will enable us to establish processing strategies in order to obtain these materials under adequate and reproducible conditions. Peer reviewed 2011-09-22T13:29:46Z 2011-09-22T13:29:46Z 2001 artículo http://purl.org/coar/resource_type/c_6501 Journal of Analytical and Applied Pyrolysis 58/59:155-172 (2001) 0165-2370 http://hdl.handle.net/10261/39867 en open Elsevier |
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Acrylonitrile Polyacrylonitrile N,N-dimethylformamide Pyrolysis Cyclization Carbon fibers Pyridine derivatives Solvents Processing Acrylonitrile Polyacrylonitrile N,N-dimethylformamide Pyrolysis Cyclization Carbon fibers Pyridine derivatives Solvents Processing |
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Acrylonitrile Polyacrylonitrile N,N-dimethylformamide Pyrolysis Cyclization Carbon fibers Pyridine derivatives Solvents Processing Acrylonitrile Polyacrylonitrile N,N-dimethylformamide Pyrolysis Cyclization Carbon fibers Pyridine derivatives Solvents Processing Sánchez-Soto, Pedro José Avilés Escaño, Miguel Ángel Río Andrade, José Carlos del Ginés, J.M. Pérez-Rodríguez, José Luis Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
description |
The polymerization of acrylonitrile to polyacrylonitrile (PAN) has been studied using several solvents: N,N-dimethylformamide (DMF), hexane, toluene, water, and in bulk form (no solvent). The addition of DMF is the only case where both monomer and polymer are soluble in the solvent. Thermal analyses of the resultant products after polymerization have been performed by differential scanning calorimetry and pyrolysis–gas chromatography:
mass spectrometry. The effect of the solvents employed as media for polymerization is interpreted from the results of the thermal and structural (X-ray diffraction) methods. The polymer samples obtained when using water or toluene as solvents have the greater content of amorphous components compared to the others. The amide molecules are difficult to
completely eliminate in the product obtained after the polymerization reaction and even after prolonged heating at 110°C and remain occluded. DMF can be considered to exert a
plasticized effect on PAN and is even capable of forming complexes by dipolar bonding. As a result of this interaction, the thermogram is quite different from the other samples studied in the present work, showing a single sharp exothermic peak. This is associated with nitrile group polymerization (cyclization) of PAN. It is deduced that the amount of heat evolved as
well as the temperature interval over which it is released are influenced by the chemical
processing of PAN, in particular when using DMF as solvent for both monomer and polymer. Pyrolysis of the different PAN samples revealed the release of occluded solvent
molecules, mainly when using DMF, and compounds produced from the thermal degradation processes. Different types of cyclized compounds, such as pyridine derivatives and aromatic nitriles were identified. All these compounds could be derived from cyclized PAN structures which are not completely degraded by the thermal treatment of pyrolysis. Alkyldinitriles have also been tentatively identified associated with the final molecular breakdown of cyclized structures with six-member rings by pyrolysis. Valuable complementary information on the structure of the PAN samples (homopolymer) obtained using the
different processing approaches involving several solvent media has been provided by
pyrolysis. The present results will improve our understanding of the evolution of the
structure and properties of carbon and activated carbon fibres which will enable us to establish processing strategies in order to obtain these materials under adequate and
reproducible conditions. |
format |
artículo |
topic_facet |
Acrylonitrile Polyacrylonitrile N,N-dimethylformamide Pyrolysis Cyclization Carbon fibers Pyridine derivatives Solvents Processing |
author |
Sánchez-Soto, Pedro José Avilés Escaño, Miguel Ángel Río Andrade, José Carlos del Ginés, J.M. Pérez-Rodríguez, José Luis |
author_facet |
Sánchez-Soto, Pedro José Avilés Escaño, Miguel Ángel Río Andrade, José Carlos del Ginés, J.M. Pérez-Rodríguez, José Luis |
author_sort |
Sánchez-Soto, Pedro José |
title |
Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
title_short |
Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
title_full |
Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
title_fullStr |
Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
title_full_unstemmed |
Thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
title_sort |
thermal study of the effect of several solvents on polymerization of acrylonitrile and their subsequent pyrolysis |
publisher |
Elsevier |
publishDate |
2001 |
url |
http://hdl.handle.net/10261/39867 |
work_keys_str_mv |
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