Effects of Surface Roughness on High-temperature Oxidation of Carbon-fiber-reinforced Polyimide Composites

Abstract

In high temperature applications, the oxidation of polymer composites changes their microstructures and degrades their mechanical properties. Both these effects detrimentally affect the service life. Oxidation experiments are time-consuming and cannot be conducted in a laboratory for all layouts of a composite. For this reason, the weight loss of a composite due to oxidation is predicted by the first-order approximation rule of mixtures. Theoretically, the shielding of fibers should slow down the oxidation of a composite than that of a neat resin. However interestingly, the predicted value of oxidation is far lower than that obtained experimentally. In the literature, some researchers have proposed the fiber-matrix interface model to explain the discrepancy while others have believed it is related to the preparation of the surface. This work presents a surface roughness model to clarify the relationship between the high-temperature oxidation and the surface roughness. Predictions concerning high-temperature oxidation are favorably supported by experimental data.

Thermal degradation of high‐temperature fluorinated polyimide and its carbon fiber composite

“…High‐temperature polyimides are finding use in a variety of applications, from electronics to aerospace, because of their high thermal stability and excellent mechanical, chemical, and electrical properties 1, 2. Additionally, fiber‐reinforced high temperature polymer matrix composites are particularly attractive for aerospace structures because of their low density,2, 3 high mechanical strength,2, 4–10 high modulus,2, 5, 7–9 thermo‐oxidative stability,2, 8, 9, 11, 12 excellent electrical properties,2, 5, 10, 13 and superior chemical resistance 2, 4, 5, 9, 14. A variety of polyimide‐based composites have been studied for use in aerospace applications 2, 5, 11, 15.…”

“…An area of concern for materials to be used in aerospace applications is the ability to withstand temperatures greater than 400°C with minimal degradation during long exposure times 2, 16. In general, polyimides are the most thermally stable polymers because of their high T g 's and high decomposition temperatures,15 but resistance to oxygen needs further study for the fluorinated polyimide composites because of some initial findings 12, 17. Most composites will exhibit microstructural changes and degradation in properties when exposed to high temperatures 12.…”

“…In general, polyimides are the most thermally stable polymers because of their high T g 's and high decomposition temperatures,15 but resistance to oxygen needs further study for the fluorinated polyimide composites because of some initial findings 12, 17. Most composites will exhibit microstructural changes and degradation in properties when exposed to high temperatures 12. Adding reinforcements to neat polyimide resin, such as carbon fiber, results in a lower weight loss because of a smaller amount of resin in the composite being subjected to degradation 17, 18.…”

Anisotropic oxidation prediction using optimized weight loss behavior of bismaleimide composites

“…Weight loss was estimated as the sum of grafted oxygen on the matrix and eliminated water and volatiles by solving a closed-loop mechanistic scheme of reactions. The effect of surface roughness on oxidation weight loss was introduced by Kung [6]. A modified rule of mixtures was developed to account for the surface roughness effect on the oxidation-exposed area.…”

Blistering in carbon‐fiber‐filled fluorinated polyimide

“…Polyimides are a class of high‐temperature polymers that have found use in a variety of applications, from electronics to aerospace, because of their high thermal stability and excellent mechanical, chemical, and electrical properties [1, 2]. In addition, fiber‐reinforced, high‐temperature, polymer‐matrix composites are particularly attractive for aerospace structures because of their low density [2, 3], high mechanical strength [2, 4–10], high modulus [2, 4, 6, 8, 9], thermo‐oxidative stability [2, 4, 9, 11, 12], electrical properties [2, 6, 10, 13], and excellent chemical resistance [2, 5, 6, 14]. Various polyimide‐based composites have been studied for use in aerospace applications for these reasons [2, 4, 6, 11, 15].…”