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

High-temperature polymers are being used for a broad range of applications, such as composite matrices for structural applications (e.g., high speed aircraft).
Polyimides are a special class of polymers that meet the thermal and oxidative stability requirements for high temperature composite aerospace applications. A
weight loss study was performed on a fluorinated polyimide resin and its carbon fiber composite in an effort to determine its thermal stability and degradation mechanisms. Experiments were conducted using a preheated oven and thermogravimetric analysis to obtain the weight loss. Regardless of the method used, the resin and composite exhibited excellent thermal stability (less than 1% weight loss) below 430
°C, regardless of 2–20 min of exposure. After 20 min of exposure at 510°
C, the composite remained relatively stable with only 5.3% weight loss using the oven technique, whereas the neat polyimide sustained 12.6%. When degradation occurred, it was found to be the result of thermolysis and oxidation (to a lesser
extent).