多频动态DMA表征PTFE密封圈在SC-CO2中的老化性能

Multi-frequency dynamic DMA characterization of aging properties of PTFE O-rings in SC-CO2 environment

采用多频温度扫描动态热机械(DMA)方法研究了PTFE O型密封圈于SC-CO2中浸泡28d过程中的性能变化。通过Arrhenius方程计算得到PTFE材料玻璃化转变表观活化能变化ΔEa,分析了PTFE材料于SC-CO2下的物理机械性能和动态力学性能变化。结果表明,不同浸泡时间下PTFE材料的ΔEa有差异,28d内ΔEa的变化值在48.466 kJ·mol^-1左右。相对于物理机械性能,ΔEa在表征材料的耐SC-CO2溶剂性能过程中对PTFE材料的性能变化更加敏感;PTFE材料经浸泡后发生了扩散和溶胀效应,质量体积变化率和硬度有小幅度的变化,断裂伸长率变化值在15.3%左右,PTFE密封圈未发生明显老化。

The multi-frequency temperature scanning dynamic thermomechanical(DMA)method was used to study the performance change of PTFE O-ring seal in SC-CO2 for 28d.The apparent activation energy changeΔEa of PTFE material was calculated by Arrhenius equation.The physical and mechanical properties and dynamic mechanical properties of PTFE materials under SC-CO2.The results show that theΔEa of PTFE materials is different under different immersion time,and the change ofΔEa in 48d is between 48.466 kJ·mol^-1.Compared with physical and mechanical properties,ΔEa is used to characterize the SC-CO2 solvent resistance of materials.The change of the properties of the material is more sensitive;the diffusion and swelling effects of the PTFE material occur after immersion,the mass volume change rate and hardness have a small change,the elongation at break changes between 15.3%,and the PTFE seal does not age significantly.