The addition reaction probably proceeds as an aminolysis as in equation 6, rather than by acidolysis of lactams by the carboxyi group in the growing chain. Thus, aminocaproie acid serves a dual function. with amine and carboxyl groups acting as initiator and as catalyst, respectively. Chain growth occurs at this stage by condensation as well as by addition. Upon completion chain growth, the polymer is in equilibrium with 6-15% or more of lower-molecular-weight substances, including lactam and lower-molecular-weight polymer. both ring and linear chains. The equilibrium ratio depends on moisture in the melt. the pressure employed during the initiation. and. to a lesser extent. on the reaction temperature