Improving the hydrophobic, water barrier and crystallization properties of poly(ethylene terephthalate) by incorporating monodisperse SiO2 particles

This paper details an improvement in the properties of poly(ethylene terephthalate) (PET) with respect to its use in petroleum engineering by incorporating uniform (monodisperse; 35 to 380 nm) silica (SiO2) particles and polystyrene-SiO2 core-shell particles by melt mixing. The resulting high-performance nanocomposite (SNPET) films are presented. The results of contact angle and water absorption tests showed that the contact angle of the amorphous SNPET films increased from 72 degrees to 118.5 degrees as the core-shell particle load increased from 0 to 6.0 wt%. The contact angle reached 128.0 degrees when the films were annealed. Decreasing the SiO2 particle size demonstrably improved the SNPET film hydrophobicity and lowered the water diffusion coefficient, i.e. SiO2 particles of 35 nm in size gave the greatest enhancement of water barrier properties. Results of transmission electron microscopy, scanning electron microscopy, atomic force microscopy and optical measurements showed the homogeneous particle dispersion and nanostructure in the SNPET films. Their transparency and haziness increased as the particle size decreased. Use of such core-shell structures meant that the uniform (monodisperse) SiO2 particles could be dispersed homogeneously in PET, and effectively improved the surface, thermal and crystallization behavior of SNPET films to produce materials with high barrier stability against water. (C) 2010 Society of Chemical Industry