Crystallization of polymers studied by temperature modulated calorimetric measurements at different frequencies

Quasi-isothermal temperature modulated DSC (TMDSC) were performed during cr ystallization to determine heat capacity as function of time and frequency. Non-reversible and reversible phenomena in the crystallization region of p olymers were distinguished. TMDSC yields new information about the dynamics of local processes at the surface of polymer crystals, like reversible mel ting. The fraction of material involved in reversible melting, which is est ablished during main crystallization, keeps constant during secondary cryst allization for polycaprolactone (PCL). This shows that also after long crys tallization times the surfaces of the individual crystallites are in equili brium with the surrounding melt. Simply speaking, polymer crystals are 'liv ing crystals'. A strong frequency dependence of complex heat capacity can b e observed during and after crystallization of polymers.