Quenching of polymer inside aluminum DSC pans: Origin of an apparent artifact

To obtain amorphous polymer samples for thermal analysis by differential scanning calorimetry (DSC), a typical procedure involves quenching the sample, which is encapsulated inside an aluminum DSC pan and lid, into liquid nitrogen or liquid nitrogen-cooled glass beads. We demonstrate that this procedure can cause an artifact endotherm in the subsequent DSC scan of the polymer. The artifact is not related to the polymer sample itself, but is possibly due to phase change of surface moisture introduced during the process of transferring into the DSC cell. A procedure to eliminate the artifact is discussed.