1 -Pentyl-2,5-pyrrolidinedione

Fig. 12 Correlation between formation of 1-pentyl-2,5-pyrrolidinedione and simultaneous decrease in tensile strength for virgin polyamide 6.6 during thermo-oxidation at 100 °C. Reprinted from [65] with permission of John Wiley Sons, Inc. John Wiley Sons, Inc (2002)...

From Figs. 12 and 13 it is clear that the largest reduction in tensile strength coincided with the large increase in the amount of 1-pentyl-pyrrolidinedione. 

Fig. 6 Chromatograms of extractions from virgin and recycled polyamide 6.6 after 25 h of thermo-oxidation at 100 °C. Identity of the peaks is 1 = cyclopentanone, 2 = 2-methylpyridine, 3 = pentanoic acid, 4 = butanamide, 5 = 2-ethylcyclopentanone, 6 = 2,4,6-trimethylpyridine, 7 = pentanamide, 8 = 3-(l-methylethyl)pyridine, 9 = 2-butylpyridine, 10 = N,N-hexamethylenebisformamide, 11 = 2-butylcyclopentanone, 12 = glutarimide, 13 = l-propyl-2,5-pyrrolidinedione, 14 = 2-pentylcyclopentanone, 15 = caprolactam, 16 = azepane-2,7-dione, 17 = 2-cyclopentyl-cyclopentanone, 18= l-butyl-2,5-pyrrolidinedione, 19 = l-pentyl-2,5-pyrrolidinedione, 20 = 2-butyl-3,5-dimethylethylpyridine, L1-L7 = linear C13-C17 alkanes and alkenes from lubricant, = silicone from septa used to seal vials. Reprinted from [65] with permission of John WUey Sons, Inc. John Wiley Sons, Inc (2002)...

A good correlation between the formation of degradation products and the simultaneous reduction in tensile strength during thermo-oxidation was observed [65]. Figures 12 and 13 show the increase in the relative amount of the most abundant thermo-oxidation product, l-pentyl-2,5-pyrrolidinedione and the simultaneous decrease in tensile strength for virgin and once recycled material, respectively. 

Four groups of degradation products, cyclic imides, pyridines, chain fragments and cyclopentanones were identified in thermo-oxidised PA 6,6. After 1,200 h of thermooxidation, l-pentyl-2,5-pyrrolidinedione (denoted by R3 in Figure 2.2) was the most abundant degradation product. Approximately four times more 1-pentyl-2,5-... 

Figure 2.2 Relative peaks are of l-pentyl-2,5-pyrrolidinedione (denoted by R3) extracted from virgin and recycled PA 6,6 after 25, 100, 500 and 1,200 h of thermo-oxidation at 100 °C. Reproduced with permission from M. Groning and M. Hakkarainen,of Applied Science, 2002, 86. 13, 3396. 2002, Wiley...

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