State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China.
Center for Civil Aviation Composites, Shanghai Key Laboratory of Lightweight Structural Composites, Donghua University, Shanghai 201620, China.
Molecules. 2023 Mar 7;28(6):2425. doi: 10.3390/molecules28062425.
The rapid development of hydrogen fuel cells has been paralleled by increased demand for lightweight type IV hydrogen storage vessels with high hydrogen storage density, which raises the performance requirements of internal plastic liners. An appropriate manufacturing process is important to improve the quality of polymer liners. In this paper, DSC, WAXD, a universal testing machine and a differential pressure gas permeameter were used to investigate the effect of the cooling rate of the rotational molding polyamide 11 on the thermal, crystallization, mechanical and barrier properties. The cooling rate is formulated according to the cooling rate that can be achieved in actual production. The results suggest that two PA11 liner materials initially exhibited two-dimensional (circular) growth under non-isothermal crystallization conditions and shifted to one-dimensional space growth due to spherulite collision and crowding during the secondary crystallization stage. The slower the cooling process, the greater the crystallinity of the specimen. The increase in crystallinity significantly improved the barrier properties of the two PA11 liner materials, and the gas permeability coefficient was 2-3-fold higher than at low crystallinity. Moreover, the tensile strength, the tensile modulus, the flexural strength, and the flexural modulus increased, and the elongation at break decreased as the crystallinity increased.
氢气燃料电池的快速发展，对具有高储氢密度的轻型 IV 型氢气储存容器的需求也随之增加，这提高了内部塑料衬里的性能要求。适当的制造工艺对于提高聚合物衬里的质量很重要。本文使用差示扫描量热法（DSC）、广角 X 射线衍射（WAXD）、万能试验机和差压气体渗透仪，研究了旋转模塑聚酰胺 11 的冷却速率对其热性能、结晶性能、机械性能和阻隔性能的影响。根据实际生产中可达到的冷却速率来制定冷却速率。结果表明，两种 PA11 衬里材料在非等温结晶条件下最初表现出二维（圆形）生长，由于二次结晶阶段球晶的碰撞和堆积，转变为一维空间生长。冷却过程越慢，样品的结晶度越高。结晶度的增加显著提高了两种 PA11 衬里材料的阻隔性能，气体渗透系数比低结晶度时提高了 2-3 倍。此外，随着结晶度的增加，拉伸强度、拉伸模量、弯曲强度和弯曲模量增加，而断裂伸长率降低。
