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  • 1 Universidad de Sevilla Instituto de Ciencia de Materiales de Sevilla (ICMSE), Centro Mixto Consejo Superior de Investigaciones Científicas (C.S.I.C.) c/Americo Vespucio s/n, Isla de la Cartuja 41092 Sevilla Spain c/Americo Vespucio s/n, Isla de la Cartuja 41092 Sevilla Spain
  • 2 Universidad de Sevilla Departamento de Farmacia y Tecnología Farmaceútica, Facultad de Farmacia c/Profesor García González s/n 41071 Sevilla Spain c/Profesor García González s/n 41071 Sevilla Spain
  • 3 C.S.I.C. Instituto de Recursos Naturales y Agrobiología de Sevilla P.O. Box 1052 41080 Sevilla Spain P.O. Box 1052 41080 Sevilla Spain
  • 4 Universidad de Málaga Departamento de Ingeniería Civil, de Materiales y Fabricación, Escuela Técnica Superior de Ingenieros Industriales 29013 Málaga Spain 29013 Málaga Spain
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Abstract  

This paper examines the polymerization of acrylonitrile to poly(acrylonitrile)(PAN), and its cyclization, in bulk form and using N,N-dimethylformamide (DMF) as solvent in which both monomer and polymer are soluble. Thermal analysis of the resultant products after polymerization has been performed by DSC and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Scanning electron microscopy has been used to study the morphology of the resultant products and after thermal treatments. The DSC thermal curve of PAN-DMF sample is quite different from the PAN bulk sample, showing a single sharp exothermic peak associated with nitrile group polymerization (cyclization) of PAN at lower temperature (240°C) than that of bulk PAN sample (314°C). Cyclization of PAN was confirmed by IR spectroscopy. It was found that the amide molecules are difficult to eliminate completely in the product obtained after the polymerization reaction, even after prolonged heating at 110°C, and remain occluded. The formation of a complex by dipolar bonding is also possible and it is discussed. It is concluded 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 when using DMF as solvent of both monomer and polymer. Pyrolysis of these PAN samples revealed the release of occluded molecules of DMF, and several compounds containing nitrogen produced from the thermal degradation processes. All these results are interesting to know the chemical processing of carbon fibres and activated carbon fibres from PAN modified precursors.