The Solidification of PEEK. Part I: Morphology

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Abstract
The morphology of PEEK was explored using a combination of several microscopic and specimen preparation techniques: freely crystallized and cryogenic frac ture surfaces were investigated by scanning electron microscopy (SEM), thin films by transmission electron microscopy (TEM) The thin film studies show the effect that pro cessing conditions have on the morphology in PEEK. A well connected and homogeneous spherulitic structure grows at lower temperatures. At higher temperatures, when the crystalline growth slows down, more time is left for segregation between highly crystalline and noncrystalline phases. This produces a microstructure of singular spherulites sepa rated by broad regions of noncrystalline material. PEEK bulk material did not show a spherulitic structure, when processed under standard conditions, except for one system: carbon fiber-filled PEEK. Furthermore, a two-stage replicating technique was successfully introduced to the composites, thus making their structure accessible to the high resolving power of the TEM.