Poly (ethylene terephthalate) (PET)-silica (SiO2)/Polystyrene (PS) nanocomposite films were prepared by melting PET with the core-shell SiO2/ PS nanoparticles. Differential scanning calorimetry (DSC) results showed that the crystallization temperature of PET-SiO2/PS nanocomposite films with 2 wt.% PS-encapsulated SiO2 nanoparticles reached 205.1 degrees C, 11.6 degrees C higher than that of PET. For crystallized PET-SiO2/PS nanocomposite films, double melting peaks appeared in DSC curves similar to PET. Scanning electron microscopy revealed a netlike fibre morphology for the amorphous PET-SiO2/PS nanocomposite films with 2 wt.% PS-encapsulated SiO2 nanoparticles. The light transmittance of these amorphous PET-SiO2/PS nanocomposite films reached 87.9%, compared to 84.2% for PET. With the increase of annealing temperature from 110 to 150 degrees C, the transmittance of PET-SiO2/PS natiocomposite films decreased slowly from 69.9 to 46.9%, while their haziness increased slightly from 45.8 to 48.2%. All these phenomena are suggested to result from the strongly heterogeneous nucleation of PS-encapsulated SiO2 nanoparticles in PET. (c) 2006 Elsevier B.V. All rights reserved.