Study of blister phenomena on polymer liner of type IV hydrogen storage cylinders

Type IV hydrogen storage cylinder is a rising high-pressure hydrogen storage equipment, which is composed of a polymer liner and a fully wrapped carbon fiber composite. It is found that local blisters occur on polymer liners after rapid depressurization tests during the research and development process. Some manufacturers choose to add adhesives at the liner-composite interface to avoid blisters. In order to study the effect of adhesives to the local blisters, two type IV cylinders have been manufactured and tested, in which one has adhesives at the interface and the other does not. The depressurization tests were conducted from around 70 MPa–2 MPa under various mass flow rates. Digital radiography (DR) and videoscope have been used to conduct post-test inspections. Finite element analysis (FEA) was performed to verify the effect of adhesives, as well as estimating the pressure differential at the interface based on test results. According to the results of the test and FEA results, the use of adhesives at the interface does not effectively prevent the occurrence of local blisters. However, it does serve to slow down the blister propagation though. The results also indicate that the mass flow rate plays a crucial role in affecting the size of the local blister. Furthermore, based on the test and FEA results, an estimation of the local pressure differential at the interface that causes local blister was made. During the post-test inspection, it was observed that the size of several blisters initially increased but eventually decreased over time. Additionally, adjacent blisters were observed to merge as a single larger blister after the hydrostatic test. These results provide valuable insights into the formation and behavior of local blisters, which can inform future research and practical applications in relevant fields.