Chemical modification of titanium dioxide nanoparticles with dicarboxylic acids to mediate the UV degradation in polyethylene films

This work deals with the study of the degradation of films made of low-density polyethylene (LDPE) by the incorporation of commercial titanium dioxide nanoparticles (TiO2 Nps). These nanoparticles were functionalized with three types of dicarboxylic acid, which have different length chain (glutaric, pimelic and azelaic acids), to improve their compatibility with LDPE. Besides, the effect of the functionalized TiO2 Nps concentration on the photodegradation, roughness, mechanical and thermal stability of the nanocomposites was evaluated. The obtained results show that the organic coating helps to passivate the photodegradation of LDPE; the longer carbon chain of the dicarboxylic acid, the higher active sites on filler/polymer interface, which inhibits photodegradation. Also, it was elucidated that calcium, from the functionalization, increased the thermal stability of the polymer nanocomposites when exposed to UV radiation. The thermal, physical (surface wear) and aesthetic (color) properties of polyethylene, with the functionalized nanoparticles, were less affected when exposed to the weather, where it is attributed to the UV photo-stabilization of the polymer. The resultant materials (LDPE with functionalized TiO2 Nps) can be used in diverse applications such as films for greenhouse and other agricultural applications, outdoor appliances (furniture and decks, for example), among others.