Thermal degradation of polyamides

The thermal degradation of polyamides starts with free-radical cleavage of nitrogen-carbon bonds [520]. Degradation of nylon 6 can be illustrated as follows  

When nylon 6 is heated for 100 h at 305 C, half of the nitrogen escapes from the polymer and a small amount of carbon dioxide forms [457]. This was postulated by Kamerbeek et al. as being the result of reactions of two terminal amine groups [579]  

In decomposition of nylon 6,6, there is the additional tendency for ring closure by adipic acid [509] H 

At higher temperatures, the carbamoyl ketone might convert to the Schiff base by a monomolecu- 

The route to the Schiff base may also be through elimination of an isocyanate [509]  

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Herrera, M., Matuschek, G., and Kettrup, A. (2001) Main products and kinetics of the thermal degradation of polyamids, Chemosphere 42(5) 601-607. 

Schulten, H. R., Plage, B., Ohtani, H., and Tsuge, S., Studies on the Thermal Degradation of Polyamides by Pyrolysis-Field Ionization Mass Spectrometry and Pyrolysis-Gas Ghromatography, Angew. Makromol. Chem., 155,1,1987. 

Carbon liber causes thermal degradation of polyamides at elevated temperatures [70]. Carbon does not affect the thermal stability of polymethyl methacrylates [70,71] or polystyrene [49-51], but reduces the thermal stability of polyvinyl acetate [72, 73]. Graphite improves the thermal [49, 64,65] stability of polystyrene and polyamides [38, 39,74,75],... 

F. Dabrowski, S. Bourbigot, R. Delobel, and M. Le Bras, Kinetic modelling of the thermal degradation of polyamide-6 nanocomposite. European Polymer Journal, 36 (2000), 273-84. 

Jahromi, S. Gabrielse, W. Braam, A. Effect of melamine polyphosphate on thermal degradation of polyamides a combined x-ray diffraction and solid-state NMR study. Polymer 2003, 44(1), 25-37. 

Jang, B.N. Wilkie, C.A. The effect of clay on the thermal degradation of polyamide 6 in polyamide 6/clay nanocomposites. Polymer 2005, 46, 3264-3274. 

The cyclopentanone derivatives formed are reactive and can enter into various reactions, some of which lead to crosslinking. However, during thermal degradation of polyamide 6 and polyamide 66, average molecular weight is reduced analogous to polyamide 46, see Fig. 4.69. 

Svoboda, M., Schneider, B., Stokr, J. Infrared Spectroscopic Study of the Products of Thermal Degradation of Polyamides in Inert Atmosphere, Collect. Czech Chem. Common. 56 (1991), p. 1461 - 1476... 

Table 3. Kinetic data on the thermal degradation of polyamides in nitrogen Reprinted from [a. 115] with permission from Elsevier ...

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