ISO 11357-2:2020 pdf download – Plastics -Differential scanningcalorimetry (DSc)- Part 2: Determination of glass transition temperature and step height
ISO 11357-2:2020 pdf download – Plastics -Differential scanningcalorimetry (DSc)- Part 2: Determination of glass transition temperature and step height.
The change in heat flow rate as a function of temperature is recorded and the glass transition temperature and step height are determined from the curve thus obtained.
5 Apparatus and materials
The apparatus and materials shall be as specified in ISO 11357-1.
6 Test specimens
The test specimens shall be as specified in ISO 11357-1.
7 Test conditions and specimen conditioning
The test conditions and specimen conditioning shall be as specified in ISO 11357-1.
The calibration shall be as specified in ISO 11357-1.
9.1 Setting up the apparatus
The procedure for setting up the apparatus shall be as specified in ISO 11357-1.
9.2 Loading the test specimen into the crucible
The procedure for loading the test specimen into the crucible shall he as specified in ISO 11357-1.
Determine the mass of the test specimen to the nearest 0j mg. Unless otherwise specified in the materials standard, use a mass of between S mg and 20 mg. For partially crystalline materials, use a mass iiear the higher limit.
9.3 Insertion of crucibles
The procedure for inserting the crucibles shall be as specified in ISO 11357-1.
9.4 Temperature scan
9.4.1 Allow 5 mm pre-purge prior to beginning the heating cycle.
9.4.2 Perform and record a preliminary thermal cycle at a preferred scan rate of 20 K/mm, hearing the cell to a temperature high enough to erase the test material’s previous thermal history
If the loading temperature is sufficiently high above the glass transition temperature, preliminary heating can be skipped, and the temperature scan continued with 2.43.
DSC measurements on polymers are greatly affected by the thermal history and morphology of the sample and the test specimen. A first heating scan shall be performed using the test specimen as received and measurements shall be taken preferably from the second heating scan (see ISO 11357-1). In cases where the material is reactive or where it is desired to evaluate the properties of a specially pre-conditioned specimen, data may be taken during the first heating scan. This deviation from the standard procedure shall be recorded in the test report (see cluase 12).
9.4.3 Hold the temperature for S mm unless a shorter time is required due to sample decomposition.
9.4.4 Cool down to approximately 50 °C below the anticipated glass transition temperature using a preferred scan rate of 20 K/rn in.
NOTE In parhcular cases, for esample itcold crystallization is to be measured, quench cooling might have to be used.
9.4.S Hold the temperature for S mm.
9.4.6 Perform and record a second heating cycle at a preferred scan rate of 20 K/mm, heating to approximately 30 K higher than the extrapolated end temperature (T).
If melt transitions are to be evaluated, too, heating shall be done up to 30 1< higher than the extrapolated end melting temperature. Other heating or cooling rates can be used by agreement between the interested pal-ties. Preferably, the same scan rates are intended to be used for heating and cooling cycles. In particular, high scanning rates result in better sensitivity of the recorded transition. On the other hand, low scanning rates provide better resolution, Appropriate selection of rate is important to the observation of subtle transitions. NOTE Usually, a scan rate of 20 K/mm is applied which generally results in the best compromise between accuracy of glass transition temperature and sufficiently high glass transition step heighi 9.4.7 Bring the apparatus to ambient temperature and remove the crucible to determine if deformation of the crucible or specimen overflow has occurred. 9.4.8 Reweigh the crucible with the test specimen to within ±0.1 mg. 9.4.9 If any loss of mass has occurred, a chemical change should be suspected. Open the crucible and inspect the test specimen. If the specimen has degraded, discard the test results and retest, selecting a lower maximum temperature. Preferably, new crucibles shall be used for each new specimen. Re-use of crucibles shall be limited to exceptional cases and mentioned in the test report including justification. Do not re-use crucibles showing signs of deterioration for another measurement. If the test specimen overflows during measurement, clean the specimen holder assembly, following the instrument manufacturer’s instructions, and verify that the calibration is still valid. 9.4.10 Requirements for repeat testing shall be indicated by the referring standards or, if none, agreed between interested parties.