Polyamide 6 and Polyurethane Used as Liner for Hydrogen Composite Cylinder: An Estimation of Fire Behaviours

Abstract

The most advanced gas storage cylinders are composed of a high molecu- lar weight polymeric liner and fibre reinforced composite. The goal of this paper is to study in ISO 5660 cone calorimeter the thermal behaviours of carbon fibre/epoxy composite covered by a liner made of polyamide 6 (PA6) or polyurethane (PU). Time-to-ignition, amount and rate of mass loss, heat release rate, total heat release rate and effective heat of combustion were measured and calculated at three irradi- ance levels (20, 40 and 60 kW m -2 ). The main exhaust gaseous species evolution as well as oxygen consumption were also quantified during the thermal decomposition process. The transient temperatures were measured at middle-thickness of composite layer and at composite/liner interface by using K-type thermocouples. Indeed, these technical data play a significant role to choose the adequate liner to be used for full- composite cylinder application. Results show that the liner type has no effect on flaming ignition of exposed composite as well as the temperature profiles within materials. Comparing to PA6, the PU liner presents a faster melting and decomposi- tion rate (i.e. with a lower thermal resistance), a lower heat release rate levels and low major gas (i.e. CO, CO2 and NO) emission yields (i.e. a lower gaseous product toxicity). Based on the comparison of the fire-to-reaction properties, the PU thermo- plastics are recommended to be used as liner to cover gas storage composite cylinder.