Polymerization of lactams, 43. Hydrolytic copolymerization of 6‐caprolactam with 12‐dodecanelactam

Abstract

The copolymerization of 6caprolactam with 12-dodecanelactam with 2 mol-% 6-aminocaproic acid as the initiator was investigated at 260 "C within a broad concentration range of both comonomers. With increasing content of 12-dodecanelactam in the initial mixture the equilibrium content of the copolymer increased and the rate of copolymerization decreased. In the initial stage of copolymerization 12-dodecanelactam disappeared very quickly from the initial mixture; it was not incorporated into the copolymer directly, but through oligomers, probably through a cyclic dimer.The effect of temperature on the copolymerization process was examined for an equimolar composition of the initial mixture. It was demonstrated that starting with the polymerization temperature of 260 OC, the copolymers underwent degradation on long-termin heating. At 280"C, degradation occured already after 50 h of polymerization. The apparent activation energy of copolymerization, 62 kJ/mol, was calculated from the temperature dependence. ZUSAMMENFASSUNG:Es wurde die Copolymerisation von 6-Caprolactam und 12-Dodecanlactam, initiiert durch 2 mol-Yo der 6-Aminocapronsilure bei 260°C in einem breiten Konzentrationsbereich beider Comonomerer verfolgt. Mit steigendem Anteil des 12-Dodecanlactams im Ausgangsgemisch steigt der Gleichgewichtsgehalt an Copolymeren und zugleich sinkt die Copolymerisationsgeschwindigkeit. In der Anfangsphase der Copolymerisation nimmt der Gehalt an 12-Dodecanlactam im Reaktionsgemisch schnell ab, es wird jedoch nicht in das Copolymere direkt eingebaut, sondern iiber Oligomere, wahrscheinlich iiber ein cyclisches Dimeres.