ISO 11357-3:2018 pdf download – Plastics-Differential scanningcalorimetry (DSC)- Part 3: Determination of temperature and enthalpy of melting and crystallization.
enthalpy of crystallization
heat released by the crystallization of a material at constant pressure
Note I to entry: It is expressed in kilolaules per kilogram (kJ/kg or Joules per gram (Jig).
4 PrincIple
See ISO 11357-I.
5 Apparatus and materials
Apparatus and materials shall be in accordance with ISO 11357-1.
6 Test specimen
The test specimen shall be in accordance with ISO 11357-I.
7 Test conditions and specimen conditioning
The test conditions and specimen conditioning shall be in accordance with ISO 11357-1.
8 Calibration
Calibration shall be in accordance with ISO 11357-1.
9 Procedure
9.1 SettIng up the apparatus
The setting up of the apparatus shall be in accordance with (SO 11357-1.
9.2 Loading the test specimen into the crucible
The loading of the test specimen shall be In accordance with ISO 11357.1.
Unless otherwise specified in the material standard, preferably use a mass of 5 mg to 10 mg for the measurement. In the case of high or low heats of transition, masses lower or higher than 5 mg to 10 mg, respectively, may be used. In case of polymer compounds the mass shall refer to the matrix polymer.
9.3 Insertion of crucibles
The insertion shall bern au.urddiIce with ISO 11357.1.
9.4 Temperature scan
9.4.1 Heating and cooling rates other than those recommended here may be used by agreement between the Interested parties. In particular, high scanning rates result In larger effects of the recorded transition. On the other hand, low scanning rates provide higher resolution in temperature and may be appropriate in the resolution of closely overlapping transitions.
9.4.2 Allow S mm for a nitrogen pre-purge prior to beginning the heating cyde.
9.4.3 Perform and record a first heating run, heating the cell to a temperature high enough to erase the test material’s previous thermal history typically 30 K above the extrapolated end melting temperature. Ter.m. Preferred heating rates for the first heating run are 10 K/mm or 20 K/mm. but also higher heating rates may be used to delete the thermal and mechanical history of a sample within the first heating run.
DSC measurements on polymers are greatly affected by the thermal history and morphology of the sample and the test specimen. It is Important that the preliminary heat cycle be performed and the measurements be taken from the second heat 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 cycle. This deviation from the standard procedure shall be recorded in the test report.
94.4 Hold the temperature for S mm.
NOTE Longer times can be acceptable or needed provided degradation of the polymer does not result.
9.4.5 Perform and record a cooling run at preferably 10 K/mm or 20 K/mm to approximately 50 K below the extrapolated end crystallization temperature, or lower If rctiuired by the polymer to be measured.
NOTE Because of supercooling. crystallization does not occur until a sufficient temperature gradient Is available, usually significantly below the melting temperature.
If glass transitions are to be evaluated, too, cooling shall be done 50 K below the glass transition temperature or lower If required by the polymer to be measured.
9,4.6 Hold the temperiture for 5 mm.
NOTE It is important to create a defined thermal history in order to evaluate correct results.
9.4.7 Perform and record a second heating run at preferably the same heating rate as the cooling run (see 9A5) to approximately 30 K higher than the extrapolated end melting temperature. Tt,m.
9.4.8 BrIng the apparatus to ambient temperature and remove the crucibics to determine If deformation of the crucible or specimen overflow has occurred.
9.4.9 Reweigh the crucible with the test specimen, unless it is known that the material will suffer no loss in mass during the experiment
In case of significant weight loss repetition of measurements with stronger dried specimens shall be considered.
10 Expression of results.