چكيده لاتين :
The kinetics of non-isothermal crystallizations of polypropylene (PP) and PP containing
0.5 wt% single-walled carbon nanotube (PP/SWNT) were compared by
using differential scanning calorimetry technique. The non-isothermal melt crystallization
data were analyzed according to Avrami and Mo models. The values of halflife
and corrected composite rate constant of Avrami equation as well as the rate
parameter of Mo equation indicated that the crystallization rate increased with the
increasing of PP and PP/SWNT cooling rates. However, the crystallization rate of the
nanocomposite was found to be higher than that of PP at a certain cooling rate.
Nucleation efficiency (NE) defined by Fillon was obtained for PP/SWNT. It was found
that NE varied from 16.4% to 19.4% in the range of cooling rate studied. This implied
that SWNT could play as a nucleating agent for the crystallization of PP. In addition, the
effective energy barrier (ؤE) for the non-isothermal melt crystallization process was
calculated for the two materials by using the Kissinger method. The ؤE values were
determined to be 226 and 262 kJmol-1 for PP and PP/SWNT, respectively. Based on
the theory proposed by Lauritzen and Hoffman, the end surface free energy (َe) for the
two materials was calculated. The results showed that the value of َe for the nanocomposite
was lower than that of PP itself, in agreement with the fact that the rate of
crystallization is higher in the nanocomposite compared to the pristine polymer.
