Permanganic etching of PEEK

Abstract The technique of permanganic etching as already published reveals spherulitic structure and lamellar detail in polyolefines, and has recently been modified for application to isotactic polystyrene. For application to poly(aryl-ether-ether-ketone), or PEEK, neither variant is suitable, but a new modification of the etchant, based on phosphoric acid, allows the morphology of PEEK to be studied under the electron microscope, revealing differences between specimens crystallized at different temperatures.