Effect of Nanosilica Type on Properties of Polyethylene Terephthalane/Silica Nanocomposite

This research is carried out to study some properties of polyethylene terephthalate (PET) as one of the most important synthetic polymers used in textile industry. PET based nanocomposites containing three differently modified silica particles were prepared by melt compounding. The influence of type and amount of nanosilica on various properties of nanocomposite was studied by Fourier transform infrared spectroscopy، scanning electron microscopy، contact angle determination، optical microscopy، differential scanning calorimetry، thermal gravimetry analyzer and dynamic mechanical thermal analyzer. ATR results indicated that the interactions of hydrophilic nanosilica mainly occur at the surface of nanocomposites. SEM was used to confirm the presence of silica on the surface of nanocomposites and it showed that surface properties depend on hydrophilicity of nanosilica. Studies on surface tension of nanocomposites showed that modified nanosilica particles have higher tendency to remain in bulk polymer as compared with unmodified one. Optical microscopy images from nanocomposites-containing silica illustrated the increment of the number of spherulites in the PET matrix with increases in silica percentage which were dependent on nano-silica type and content. Differential scanning calorimetry results of the nanocomposites showed a slight drop in the melting temperature compared to pure PET. The results obtained from thermal stability test showed that any improvement in thermal stability depends on the type of silica and dispersion of particles in polyethylene terephthalate. Moreover، the extent of interactions between nanosilica particles and polyethylene terephthatale chains affects on thermal stability of the composite.