Mechanical and Gas Barrier Properties of Naturally and Artificially Weathered High-Performance Fiber Reinforced Laminated Structures for Stratospheric Airship Envelope

This study presents the fabrication of lightweight, strong, high-helium barrier, and weather-resistant composite laminates for stratospheric airships. Three high-performance fabrics (Spectra®, Vectran®, Kevlar®) served as the strength layer, while PVDC-treated BOPET film (Mylar®) and PVF film (Tedlar®) acted as the helium barrier and the weather-protective layer, respectively. Atmospheric plasma treatment of BOPET and PVF films optimized surface functionalization before lamination. A weather-resistant PU-based adhesive, enhanced with organic UV additives, graphene oxide, and carbon black, joined the layers, and an aliphatic thermoplastic polyurethane, similarly modified, served both as a heat-sealable sealing layer and a tie coat (incorporating a crosslinker). Graphene oxide in adhesive and sealing layers improved both the weather resistance and the helium gas barrier. Plasma functionalization effects on PVF and BOPET film surface were analyzed using AFM and T-peel strength. Composite laminates underwent accelerated artificial weathering (700 h) and natural weathering (8 month), with evaluations every 200 h and 2 months, respectively. After UV exposure, changes in peel strength, tear strength, tensile strength, and helium gas barrier were assessed. All three types of laminates performed well with minimal property deterioration, especially after 8 month of natural weathering, compared to 700 h artificial weathering. The Kevlar-based laminates demonstrated superior performance across all properties (tensile strength 968 N/cm, tear strength 513 N, and helium permeability 0.02 L/m²/24 h), showcasing significant potential for stratospheric airship envelopes.