Liu Peng, Mullins Michael, Bremner Tim, Benner Natalie, Sue Hung-Jue
Hoerbiger Corporation of America, Inc. , Houston, Texas 77023, United States.
J Phys Chem B. 2017 Jun 1;121(21):5396-5406. doi: 10.1021/acs.jpcb.7b01533. Epub 2017 May 22.
Demands for engineering applications of high performance polymers, such as the polyaryletherketone families, have grown significantly in recent years. Fundamental knowledge on the mechanical behavior of such polymers, especially under harsh environments, is still lacking. In this study, the mechanical behavior and interfacial phenomena of a blend of polybenzimidazole (PBI) particles having sizes of about 50 μm and polyetheretherketone (PEEK) matrix at 50:50 weight ratio was characterized. PBI and PEEK are known to be incompatible with each other in the dry state. The possible influence of hygrothermal exposure on interfacial bonding between PEEK and PBI has been systematically studied. Under dry conditions, the PEEK matrix dominates the dynamic mechanical behavior, indicating no noticeable viscoelastic coupling between the two phases. After being exposed to hygrothermal conditions, the T of the PEEK phase in the blend shifts to a lower temperature by as much as 26 °C. The extent of this shift is much greater than what is observed for neat PEEK alone under the same condition. Nanomechanical property mapping results indicate that the interfacial region is broadened after 288 °C hot water immersion treatment. The above finding strongly suggests the hygrothermal conditioning promotes apparent compatibility between PEEK and PBI. Likewise, the fracture behavior of the blend provides direct evidence that the interfacial adhesion is greater than the cohesive strength of either phase after water immersion. In the meantime, it is found that both fracture toughness and tensile strength of the blend are improved by water absorption at 60 °C, at the expense of a minor reduction in Young's modulus. However, if the blend is exposed to hot water at 288 °C, all of the mechanical properties will deteriorate significantly. The possible causes of the mechanical property deterioration in the PEEK/PBI blend after hygrothermal treatment are discussed.
近年来，对高性能聚合物（如聚芳醚酮家族）的工程应用需求显著增长。然而，关于此类聚合物力学行为的基础知识，尤其是在恶劣环境下的力学行为，仍较为缺乏。在本研究中，对粒径约为50μm的聚苯并咪唑（PBI）颗粒与聚醚醚酮（PEEK）基体按重量比50:50混合而成的材料的力学行为和界面现象进行了表征。已知PBI和PEEK在干燥状态下互不相容。系统研究了湿热暴露对PEEK与PBI之间界面结合的可能影响。在干燥条件下，PEEK基体主导动态力学行为，表明两相之间没有明显的粘弹性耦合。在湿热条件下暴露后，共混物中PEEK相的玻璃化转变温度（Tg）下降多达26°C。这种下降幅度远大于在相同条件下单独的纯PEEK所观察到的情况。纳米力学性能映射结果表明，在288°C热水浸泡处理后，界面区域变宽。上述发现强烈表明湿热处理促进了PEEK与PBI之间的表观相容性。同样，共混物的断裂行为提供了直接证据，表明水浸泡后界面粘合力大于任一相的内聚强度。同时，发现60°C吸水使共混物的断裂韧性和拉伸强度均有所提高，但杨氏模量略有降低。然而，如果将共混物暴露在288°C的热水中，所有力学性能将显著恶化。讨论了湿热处理后PEEK/PBI共混物力学性能恶化的可能原因。
