The thermal characteristics of bottle grade recycled PET pellets contaminated with 5% PP prepared by
multiple extrusions were studied by differential scanning calorimetry (DSC) at constant heating rate of
10 C/min for various extrusion cycles. The peak temperature of crystallization Tc, the enthalpy of
crystallization DHc and the degree of crystallinity Xc were found to be dependent on the number of
extrusion cycles. From the dependence on extrusion cycles, the analysis of the crystallization mechanism
by Avrami model has been determined, the Avrami exponent n and the rate constant Zt were calculated
and the influence of the 5% PP on the bottle grade recycled PET matrix during multiple extrusions and its
effect on crystallinity was thoroughly discussed.