Problems in low-temperature polymerization of lactams with MAlEt4–n (Lac)n as catalyst

The NaAl(Lac)₄-catalyzed polymerization of ε-caprolactam at the medium temperature range (70–150°C) was investigated. The initiation temperature was observed to decrease to about 100°C in the case of a high concentration (such as 2.0 mole-%) of catalyst. Moreover, in the prolonged polymerization of lactams with KAl(Lac)₂Et₂ catalyst, in the absence of initiator, the low activity of aluminum lactamate as initiator was observed. In connection with the polymerization of lactams with MAl(Lac)_nEt_4–n catalyst, the reactivity of MAlEt₄ (where M is Na or K) with N-acetyllactams was investigated. The results imply that no consumption of N-acyllactams by the reaction with MAl(Lac)_nEt_4–n occurs in the course of the low-temperature polymerization of lactams.