Both super-cooling(△Tsc) and super-heating (△Tsh) temperatures of polyethylene tereph-thalate (PET) containing 0

5

10 and 15 weight percent flame retardants have been determined by DSC curves. PET with 5 wt% flame retardant has the smallest △Tsc and △Tsh

which means that it has stronger crystallizability than the others. Avrami equation for the isothermal crystallization has been extended to the non-isothermal process of the constant heating rates so that the parameters characterizing crystallization kinetcs

such as Avrami exponent n

the half life of crystallization t1/2and the crystallization rate constant K

which are usually obtained from Avrami equation

can be calculated from the extended equation for non-isother-mal crystallization. This method has been applied into the investigation of crystallization ki-netics of PET and PET with 5 wt% of flame retardant. The results show that the value of t1/2 fo PET with 5 wt% of flame retardant is smaller than that of pure PET

and that the value of n of the former is about l less than that of the latter.