Evaluation of the Influence of Modified TiO2 Particles on Polypropylene Composites.

This article reports the preparation of composites and nanocomposites of polypropylene and titanium dioxide particles, with our without surface modification, to obtain photodegradable or photostable materials with less severe environmental impacts. The modification of the titanium dioxide was carried out in the laboratory using propionic acid to improve the interaction of titanium dioxide with the polymer matrix. The composites and nanocomposites were prepared by melt extrusion using a single-screw extruder. The materials obtained were characterized by nuclear magnetic resonance relaxometry, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis and mechanical analysis (tension). The results showed that the surface modification of the titanium dioxide particles promoted their better dispersion, distribution and interaction with the polypropylene matrix, generating a nanocomposite material. The NMR relaxometry results showed that the modified particles changed the molecular dynamics, indicating the formation of nanocomposites. In the Raman spectra, peaks related to the titanium dioxide only appeared at a concentration of 1%, and there was an inversion between crystalline and amorphous phase regions in the samples with the organophilic titanium dioxide, indicating the formation of a nanocomposite. The best modified PP/TiO2 compositions were those containing 0.25 and 0.50% modified TiO2 particles. The incorporation of the titanium dioxide particles, in rutile form, promoted photostabilization of the composites and nanocomposites at all ratios, and the composition containing 0.50% modified TiO2 presented the best photostabilization.