Enhancement of bonding strength between polyethylene/graphene flakes composites and stainless steel and its application in type IV storage tanks

The low bonding strength between the thermoplastic liners and the metal bosses can easily lead to hydrogen leakage, which is one of the most important challenges for the development of type IV hydrogen storage tanks. Herein, a method incorporating graphene flakes (GFs) into polymer matrix was applied to enhance the adhesion between polyethylene (PE) and stainless steel. The adhesive bonding tests showed that the bonding strength of PE/0.5 wt% GFs composites to stainless steel was improved by an order of magnitude compared to pure PE. Contact angle tests, digital images and SEM observations were used to explore the mechanism of adhesion enhancement. The characterization test results showed that the increase in bonding strength is attributed to the mechanical interlocking caused by GFs and the strong interaction between GFs and stainless steel. This method will provide important guidance for the manufacture of the plastic liners of the Type Ⅳ tanks.