The effects of structural modifications on the critical properties of PBI fiber

Abstract The only improvement seen in increasing the molecular orientation of PBI fiber over that exhibited by presently defined target property material is the improvement seen in the strength and stiffness of the material at high strain rates. This improvement, however, cannot be extrapolated to a good impact performance. No advantage of fiber crystallization was detected in the properties measured in this evaluation conducted in accordance with the current state of the art of testing of high temperature fibers. However, as the testing of high temperature performance fibers becomes more sophisticated, advantages of crystallization undetectable in this investigation may appear. Should this occur, it would then be advisable to explore the crystallization of PBI further in an attempt to induce a higher degree of crystallinity than accomplished in this work while maintaining adequate tensile properties.