Characterisation of melt-processed poly(ethylene terephthalate)/syntheticmica nanocomposite sheet and its biaxial deformation behaviour

Background: Poly(ethylene terephthalate) (PET) iswidely used in the packaging industry. In order to enhance the mechanical and barrier properties, nanoscale fillers are added to PET matrices to form nanocomposites. In the work reported here, a melt-processed PET/synthetic mica nanocomposite sheet was characterised to determine the effect of the incorporation of synthetic mica on the sheet properties and also to see if these properties are an indicator of subsequent performance under high-speed, high-temperature biaxial deformation, typical of processes such as stretch blowmoulding. Results: The incorporation of synthetic mica was found to enhance the modulus, particularly above the glass transition temperature, and barrier properties of the extruded sheet and it significantly altered the deformation behaviour of PET under biaxial deformation. The plastic flow of PET during biaxial deformation was found to diminish for the nanocomposites, and strain hardening occurred earlier. Conclusion: The modulus and barrier properties of PET were enhanced by the incorporation of synthetic mica. Clay loading also altered the biaxial deformation behaviour of PET.