“…The shift of the cycle-chain equilibrium depends not only on temperature, but also on the structure of the monomer (number of atoms in the ring). In equilibrium polymerization products of the so-called higher lactams, above all 12-dodecanelactam 1,2) or 8-octanelactam 3) , the content of cyclic oligomers is several times higher than that of unreacted monomer. About 70% of the low-molecular extractable fractions of the equilibrium products of 6-hexanelactam polymerization consist of the unreacted lactam, the rest being the cyclic and linear oligomers.…”