What could cause a double melting peak on PLA second heating curve?

26 September 2021 1 9K Report

Hey all,

I know that seeing a double melting peak of processed PLA in the first heating curve is not unusual, especially with 3D extruded samples. However, when doing DSC of an irradiated PLA sheet I found a double melting point in the second heating curve as well. The sample pans were sealed and did not burst. Could this be due to irradiation induced chain scission or the differences in L and D oriented monomers?

Antonella Battisti

It could depend on the cooling rate after first cycle.

Before making hypoteses, I suggest trying different cooling rates after first heating, and see if the double peak remains.

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