Enhancing the Weather Resistance and Helium Gas Barrier Properties of Polyurethane Nanocomposites through the Synergism of Organic UV Additives with Organoclay, Graphene, and UV-Shielding Nanopowders

This paper reports a comparative study of the synergistic effects between organic UV additives and nanomaterials of different morphologies─nanoclay, functionalized graphene, and nanoparticles (calcined TiO₂/ZnO-based UV shielding nanopowders (USN))─on the weather resistance and helium gas barrier properties of polyurethane (TPU) nanocomposite films. Improvement in nanomaterial dispersion was observed in the presence of organic UV additives. The morphological analysis showed exfoliated structures for TPU/clay and mixed intercalated/exfoliated structures for TPU/graphene nanocomposites. Nanocomposites without organic UV additives exhibited increased storage modulus and glass transition temperature, while organic UV stabilizers induced slight plasticization. Prior to weathering, clay-based polyurethane nanocomposites demonstrated superior helium barrier properties, followed by graphene- and then USN-based systems. After accelerated weathering, only clay-based nanocomposites showed significant deterioration in barrier and tensile properties, whereas graphene and USN-based nanocomposites retained their properties better. The inclusion of organic UV additives provided synergistic enhancement, resulting in superior retention of tensile and barrier properties after UV exposure compared with only nanomaterial-incorporated nanocomposite systems. These findings highlight the promise of such multifunctional nanocomposite films for applications requiring both weather resistance and gas barrier performance, such as lighter-than-air structures.