Permeability and mechanical properties of nanoclay/epoxy liner used in type IV liquid oxygen vessel: experimental and numerical study

Consideration of the permeability and safety aspects of liquid oxygen (LOX) storage is of particular importance, because oxygen leaks can break down spacecraft missions. In this study, the effect of adding nanoclay to epoxy resin on the bending and tensile capacities of a clay/epoxy nanocomposite for using as a liner in type IV LOX was investigated experimentally and statistically. Consequently, samples were initially made with different nanoclay contents (0.5%, 1%, 3%, and 5% all by weights) using two distinct dispersion processes (HSS and ultrasonic), then evaluated using bending, tensile, and permeability testing methods, as well as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). In the optimal sample with 1% (weight) of nanoclay mixed with ultrasonic process, the permeability was reduced by 35%, the Young's modulus was improved by 3.5 times, and the toughness and fracture energy were increased by 3 times compared to the pure resin. However, all samples lost between 10 and 20% of their tensile strength due to the breakage of polymer chain links. Simulation findings revealed that at burst pressure, the tank with modified resin liner deforms four times less than PP and 50% more than PET without any rupture.