PRIMARY THERMAL-DECOMPOSITION PROCESSES IN ALIPHATIC POLYAMIDES

The primary thermal decomposition processes of a series of aliphatic polyamides were investigated by Direct Chemical Ionization (DCI) and Tandem mass spectrometry. Results show that an intramolecular exchange process is the preferred thermal decomposition mechanism for many of the polyamides. Decomposition through a C-H hydrogen transfer reaction appears to occur as a secondary thermal process, except in the phase of nylon 3 because of its particular structure. A quite different decomposition pathway is followed by nylons from adipic acid (nylons 6.6 and 11.6), where specific structural factors make the formation of cyclopentanone preferred. These polymers decompose via a C-H hydrogen transfer to nitrogen with the formation of compounds having amine and/or ketoamide end groups. These primary products further decompose or react with the formation of cyclopentanone and compounds bearing amine and/or Schiff base groups.