Summary: This article reports on the dynamic mechanical and thermal properties of thermosetting phenylethynyl‐terminated polyimide (PETI‐5) composites reinforced with expanded graphite (EG) nanoplatelets having various average particle sizes and content. The EG nanoplatelets with varying particle sizes were prepared by different pulverization techniques through intercalation and exfoliation of natural graphite flakes. The effect of the EG particle size and concentration of the thermal behavior of PETI‐5/EG composites was investigated with several thermal analysis methods (DMA, TMA, and DSC). The storage modulus dynamic mechanical properties and glass transition temperature significantly increased with increasing concentration of EG nanoreinforcements regardless of size. The coefficient of thermal expansion significantly decreased, especially in the glass transition region.
Graphite fiber reinforced poly(ether ether ketone) (PEEK) and graphite fiber reinforced bismaleimide (BMI) composite materials are two kinds of advanced fiber-reinforced polymer matrix composites with good thermal stability and excellent mechanical properties at high temperature. They are currently receiving considerable attention. the main limitation on their application is the lack of knowledge regarding their behaviors during extended use at high temperature. Thermal aging properties are the main parameters for new polymer matrix composites that will be used in advanced spacecraft structural components. From the results of thermal aging effects on the properties—including interlaminar shear strength, drop-weight impact strength, and impact energy—of graphite/PEEK and graphite/BMI composites, it is found that unidirectional graphite fiber reinforced composites retain higher strength compared to multidirectional, and that multidirectional graphite/PEEK composites keep higher property retentions than multidirectional graphite/BMI composites after thermal aging at 190°C. From scanning electron photomicrographs, it is also found that graphite/PEEK composites have better fiber/resin adhesion, intraply adhesion, and microcrack resistance compared to graphite/BMI composites after thermal aging. 相似文献