Ⅳ型储氢气瓶内衬材料的氢渗透行为分子动力学模拟

Molecular dynamics simulations on hydrogen permeation of modified polymer liner for typeⅣstorage vessels

用于高压储氢的Ⅳ型储氢气瓶,其聚合物内衬材料的氢阻隔性能对于气瓶的质量起着至关重要的作用。以聚合物内衬材料聚乙烯(PE)和聚酰胺(PA6)为研究对象,对氢气在PE和PA6中的传输过程进行分子动力学模拟和蒙特卡洛模拟,计算了氢气在聚合物材料中的溶解度系数、扩散系数和气体渗透系数。通过气体渗透试验论证了分子动力学模拟材料阻隔性能的可行性。结果表明:在0.1 MPa下,随着温度从288 K升至328 K,PE,PA材料的气体的溶解系数降低,气体扩散系数增大,由于扩散作用占主导地位,材料的气体渗透系数分别增大了1.0%,80.3%。在41.6,52,60 MPa等工况下也得出了与上述基本一致的变化趋势。此外,通过模拟发现石墨烯和有机蒙脱土改性可以降低气体在材料中的扩散系数。

The hydrogen barrier performance of the polymer liner material of TypeⅣhydrogen storage cylinders used for high-pressure hydrogen storage plays a crucial role in the quality of the cylinders.The polymer liner materials-polyethylene(PE)and polyamide(PA6),were used as the research objects to conduct molecular dynamics simulations and Monte Carlo simulations of hydrogen transport processes in PE and PA6 to calculate the solubility coefficients,diffusion coefficients and gas permeability coefficients of hydrogen in polymeric materials.The feasibility of molecular dynamics simulation of the barrier properties of the materials was demonstrated by gas permeation experiments.The results show that the dissolution coefficient of gases of PE and PA materials decreases and the gas diffusion coefficient increases as the temperature increases from 288 K to 328 K at 0.1 MPa.And the gas permeability coefficient of the materials increases by 1.0%and 80.3%,respectively,due to the predominance of diffusion.The same trend as above is also obtained for the operating conditions of 41.6 MPa,52 MPa and 60 MPa.In addition,it is found that graphene and organic montmorillonite modification can reduce the diffusion coefficient of gas in the material by simulation.