Dispersibility of Hydrophilic and Hydrophobic Nano-Silica Particles in Polyethylene Terephthalate Films: Evaluation of Morphology and Thermal Properties

The development of polyethylene terephthalate (PET) nanocomposites with different nano-fillers has been an especially intense area of research due to an enhancement in thermal and physical properties of nanocomposites compared to pure PET. In this regard, the surface properties of nano-particles and their interactions with PET chains have a critical role on different properties of prepared nanocomposites. The aim of this paper is to study the influence of the type of nano-silica particles with different surface properties on the dispersibility, the interfacial adhesion, surface morphology, nucleation and thermal properties of the resultant PET/silica nanocomposites. For this purpose, PET composites containing hydrophilic or hydrophobic nano-silica were prepared by melt compounding. Different properties of nanocomposites were investigated using polarized optical microscopy (POM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), dynamical mechanical thermal analysis (DMTA) and contact angle measurements (CAM). POM images indicated that nano-silica tended to increase the number of spherulites in the PET composite structure depending on the type of particles. The thermal studies of the nanocomposites showed a slight decrease in the melting temperature compared to the pure PET.