PET nanocomposite materials exhibit improved physical properties in a PET composite as a result of the intercalation of non smectite-type clay materials while maintaining transparency and barrier properties. In some aspects, kaolin particles are modified with potassium acetate (KAc) to increase interlamellar distances and improve particle dispersion. In other aspects, calcined kaolin particles are used and may be chemically treated by an aqueous alcohol solutions method. Any loss in the molecular weight of PET composite can be offset by the further incorporation of surface compatibilizers such as silane coupling agents and other process additives such as molecular chain extenders.