crystalline or amorphous

[Davidflakejr]

If a crystalline material is heated to the point that the crystallites are in random order, isnt that "by definition" in an amorphous state?

[rickbatey]

It's their cooled state and how they behave that determine if they are semi-crystalline or amorphous. Remember that steel changes from body centered to face centered cubic structure when heated (boy, THAT was from early college MANY years ago).
Rick.

[Davidflakejr]

agreed, yet this caused much debate among the process techs at work.

[Suhas]

The morphology (amorphous or crystalline) is the state in which a particular material exists. Example, H20 is ice when it is crystalline and is below 32 deg F, water when it is liquid between 32 and 212 deg F and and steam when it is gaseous above 212 deg F. Similarly, if you have a material with crystallites in there then it is in the crystalline state, but if you subject it to a temperature where the crystallites are gone, then it is in the amorphous state. For LCPs (Liquid Crystalline Polymers), the molecules have some orientation & arrangement even in the melt and hence the melt is considered crystalline (so the name Liquid Crystalline Polymer).
The main thing here to remember that it is a state just as state of humans - happy, angry, sad, etc
Regards,
Suhas