ISOTHERMAL MELT AND COLD CRYSTALLIZATION KINETICS OF POLY(ARYL ETHER ETHER KETONE KETONE) (PEEKK)

Isothermal melt and cold crystallization kinetics of PEEKK have been i nvestigated by differential scanning calorimetry in two temperature re gions. During the primary crystallization process, the relative crysta llinity develops with a time dependence described by the Avrami equati on, with exponent n = 2 for both melt and cold crystallization. The ac tivation energies are -544.5 and 466.7 kJ/mol for crystallization from the melt and amorphous glassy state, respectively. The equilibrium me lting point T-m(o) is estimated to be 371 degrees C by using the Hoffm an-Weeks approach. The lateral and end surface free energies derived f rom the Lauritzen-Hoffman spherulitic growth rate equation are sigma=1 0 erg/cm(2) and sigma(e) = 60 erg/cm(2), respectively. The work of cha in folding q is determined as 3.98 kcal/mol. These observed crystalliz ation kinetic characteristics of PEEKK are compared with those of PEEK . (C) 1997 Elsevier Science Ltd.