Poria Kaveh - Polymer Engineering Center, Islamic Azad University, South Tehran Branch, Tehran, Iran.
Mehrzad Mortezaei - Polymer Engineering Center, Islamic Azad University, South Tehran Branch, Tehran, Iran.
Mehdi Barikani - Department of Polyurethane, Faculty of Polymer Science, Iran Polymer and Petrochemical Institute, Tehran, Iran.
Atefeh Kaveh - Islamic Azad University, Shiraz Branch, Shiraz, Iran.

Polymeric materials have long been utilized for packaging applications. However, overwhelming demands in the marketplace have put significant pressure for materialdevelopers to pursue novel routes to manufacture low cost packaging films with greatly improved barrier properties [1].The emergence of polymer nano-composites introduces a newopportunity to improve barrier properties of polymers. When the nano-platelets are well exfoliated, in addition to theimproved barrier property, polymer nano-composites usually exhibit enhanced mechanical properties and better thermalstability [1, 2]. Graphene has a high basal plane elastic modulus, E ≈ 1 TPa; ultimate strength, σ ∼ 130 GPa; and room temperature chargecarriermobility, μ ≈ 10 000 cm2/V s. Adding highly exfoliated carbon layers can significantly alter mechanical and electrical properties of polymers at extremely small loading [3]. Unlikecarbon nanotubes that can provide similar mechanical and electrical benefits, these impermeable two-dimensional sheetscan reduce gas permeability of host membranes [4]. In the present study, the effect of graphene on gas barrier performance of thermoplastic polyurethane (TPU)/graphene nano-composites was investigated. For this propose, TPU was reinforced with various contents of graphene (0-2 wt.%)through solvent blending procedure. The physical and mechanical properties of the prepared nano-composites wereinvestigated through transmission electron microscopy (TEM), wide angle X-ray reflectance diffraction (WAXD), dynamic mechanical analysis (DMA) and differential scanning colorimetery (DSC), as well as, tensile strength and gas permeability measurements.