Crystallization kinetics of compatibilized blends of polypropylene and polyethylenimine

In this paper, isothermal and non-isothermal crystallization behaviour of neat polypropylene (PP), blends of PP/maleic anhydride grafted polypropylene (PP-g-MA), and PP/PP-g-MA/polyethylenimine (PEI) has been studied by differential scanning calorimetry (DSC). DSC analysis confirmed that PEI promotes crystallization of PP for blends compatibilized with reactive co-agent PP-g-MA, that was confirmed by decreased crystallization time in compatibilized PP-PEI blends as compared to neat PP. The Avrami equation has been used to analyze isothermal crystallization kinetics for all the compositions. Determined Avrami exponent's (n) values confirmed three-dimensional crystal growth in all the samples and PP sample with 1% PEI and 1% PP-g-MA (PP/1PP-g-MA/1PEI) was found to have the least crystallization half time (t(1/2)). In addition to this, activation energy ( increment E-a) for PP/1PP-g-MA/1PEI blend decreased remarkably as compared to neat PP. The non-isothermal crystallization kinetics was studied by Jeziorny extended Avrami and Mo theories. Application of Jeziorny-Avrami equation showed larger value of log k' in case of PP/1PP-g-MA/1PEI indicating enhanced rate of crystallization. Lower value of Mo's parameter F(T) for PP/1PP-g-MA/1PEI than neat PP established higher crystallization rate for the compatibilized blend and hence supported the prior results.