Non-isothermal crystallization analysis of isotactic polypropylene filled with titanium dioxide particles modified by a dicarboxylic acid

In this work, the non-isothermal crystallization behavior of polypropylene (iPP), induced by a dicarboxilic acid linkage at the surface of commercial titanium dioxide (TiO2), was investigated. The modification of TiO2 particles with pimelic acid (c-TiO2) played an important role in improving the crystallization kinetic parameters, as observed by an increase in the temperature of the crystallization peak during the incubation period (Atc). Jeziorny analysis suggested that the dominant secondary crystallization process occurs by nucleation on pre-existing crystals and is mainly the two-dimensional extension of the lamellar crystals formed during primary crystallization. As shown by the model of Mo, composites with c-TiO2 particles exhibited a high crystallization rate when the relative crystallinity exceeded the earliest crystallization stage. Activation energies were also determined and higher values were found for the studied composites, compared to neat iPP. These results show how the ability to nucleate into iPP is improved by c-TiO2 particles, which also increase the affinity to iPP chains, minimizing the energy required to reach the crystalline state. (C) 2016 Elsevier B.V. All rights reserved.