Synergistic effect of aryl heterocyclic aluminum phosphate and sodium laurate on non-isothermal crystallization kinetics of isotactic polypropylene

Kinetics of non-isothermal crystallization of isotactic polypropylene (iPP)/nucleating agent blends was studied for the nucleation mechanism. Avrami, Jeziorny, and correctional Friedman methods were applied to analyze the non-isothermal crystallization of the iPP/aryl heterocylic aluminum phosphate/sodium laurate (iPP/AHP-Al/L-Na) blends. For a given cooling rate of 10 degrees C min(-1), the onset temperature (T-o) and crystallization temperature (T-c) of the iPP/AHP-Al/L-Na blends increased by 4.19 degrees C and 3.57 degrees C, respectively, compared to iPP/L-Na. The T-o and T-c of iPP/AHP-Al/L-Na blends increased by 2.13 degrees C and 1.79 degrees C, respectively, compared to iPP/AHP-Al, when the AHP-Al mass fraction reached 1.2 parts per thousand. The effective activation barrier (Delta E) for non-isothermal crystallization was the least when the AHP-Al mass fraction was 0.8 parts per thousand. The value of the initial slope of the exotherm increased with the addition of AHP-Al monotonically. All these findings indicated that AHP-Al could improve the initial crystallization rate and also that the addition of AHP-Al/L-Na reduced the Delta E for non-isothermal crystallization. It is speculated that an ion exchange reaction between AHP-Al and L-Na occurs during the mixing process and could be possible that this results in the generation of a more efficient nucleating agent.