Multiple Melting Peaks of Polyethylene

The profile of the DSC curves for the melting of crystalline polymers is closely related to the conditions under which the crystal formed. For example, heat polyethylene to 120 °C and maintain it for a definite period of time. After the sample has completely melted, allow it to cool to 

110 °C. Maintain this temperature for 2 minutes, followed by rapid cooling to room temperature. Repeatedly treat the sample in the same way for several cycles, reducing the maximum temperature progressively by 5 C in each cycle. The heating curve for a sample subjected to such 

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