Effects of surface preparation on bond behavior CFRP-to-PA6 bonded joints using different adhesives

This paper focuses on an experimental study of the explosive decompression on representative samples of the hyperbaric type IV hydrogen storage vessels. The adhesion of the composite to the liner is achieved by different adhesives. The bond behavior of liner-to composite bonded joint considerably depends on the properties of adhesives, as well as the assembly process. X-ray tomography allows determining the damages before and after explosive decompression tests. Tomographic observations have revealed a certain level of porosity due to the assembly process with plasma treatment. This porosity influences the damage mechanisms induced by explosive decompression. Results show that 1) the increasing of the maximum hydrogen pressure (differential pressure induced during the depressurization step between the liner/adhesive interface or the adhesive/composite) increases the risk of liner collapse for the same gas exposure conditions, 2) Compared with soft adhesive, the stiff adhesive has proven better adhesion between the composite and the liner, 3) the flame treatment improved the surface energy of the PA6 and subsequently increased the collapse limit pressure, 4) adhesive RCA-20 with plasma preparation can be defined as a kind of low strength to collapse adhesive with a collapse limit pressure less than 2 MPa, 5)adhesive RCA-2000 with flame treatment can be defined as a kind of high strength to collapse adhesive in the present report with a collapse limit pressure between 15 MPa and 17.5 MPa.