Chemistry Reference
In-Depth Information
In decomposition of
nylon 6,6,
there is the additional tendency for ring closure by adipic acid [
509
]:
H
H
OH
N
Δ
N
4
O
+
Η
2
Ο
O
O
O
NH
2
+
+
CO
2
O
The cyclization reaction can also occur as follows [
509
]
H
H
H
Δ
N
N
N
4
+
H
2
N
O
O
O
O
or, perhaps, as a bimolecular reaction [
509
]:
H
H
N
N
2
CO
2
+
+
O
O
O
N
O
At higher temperatures, the carbamoyl ketone might convert to the Schiff base by a monomolecu-
lar process [
509
]:
C
N
CO
2
+
H
O
O
N
The route to the Schiff base may also be through elimination of an isocyanate [
509
]:
C
N
+
O
C
N
H
O
O
N
Rather than thermal degradation of nylon 6, it is possible to depolymerize this polyamide. Kamimura
and Yamamoto reported that it is possible to depolymerize this nylon back to caprolactam [
510
]:
