Crystallization of Isotactic Polypropylene Nanocomposites with Fibrillated Poly(tetrafluoroethylene) under Elevated Pressure

Nanocomposites of isotactic polypropylene with 1-5 wt.% of fibrillated PTFE (PP/T) were prepared, and their crystallization during cooling under elevated pressure, in a wide pressure range, up to 300 MPa, as well as the resulting structure, were examined. The crystallization peak temperatures of PP/T, especially with 3 and 5 wt.% of PTFE, exceeded by up to 13 degrees C those of neat PP. Moreover, a fine-grain structure was formed in PP/T in the entire pressure range, which proved the ability of the fibrillated PTFE to nucleate crystallization of PP in the gamma-form under elevated pressure. This also resulted in a higher crystallinity level developed in the gamma-domain, before the temperature range of the alpha-domain was reached during cooling. Hence, the gamma-content increased in comparison to that in neat PP, under the pressure up to 200 MPa, especially under 50-100 MPa.

Automated summary

This study prepared nanocomposites of isotactic polypropylene with fibrillated PTFE and investigated their crystallization behavior and resulting structure under high pressure. It was found that the addition of fibrillated PTFE increased the crystallization peak temperature of polypropylene and formed a fine-grain structure. This suggests that fibrillated PTFE can promote the crystallization of polypropylene under high pressure.