ISO 6721-11-2012 pdf free download.Plastics一Determination of dynamic mechanical properties一 Part 11: Glass transition temperature.
9 Test procedure
9.1 Test atmosphere
This shall be in accordance with ISO 6721:2011, 9.1
NOTE Measurements can be undertaken under static air conditions or an inert atmosphere. However, it is important
that the calibration and the specimen tests be performed under identical conditions.
9.2 Assessment of heating rate dependence
9.2.1 Heating rate dependence — Procedure
Calibrate the instrument in accordance with Annex A. Position the temperature sensor in the instrument as closely as possible to the sample under test, but ensuring it is not touching it. The position of the sensor shall remain undisturbed for subsequent specimen tests. If moved, recalibration may be necessary (see Annex A).
Undertake tests according to Method A (see 9.3.1) to assess the heating rate dependence of the material/equipment.
9.2.2 Heating rate dependence — Results
If the temperature at the inflection points is shown to vary by more than ±2 CC between the different heating rates, use Method A (see 9.3.1).
NOTE For this case, a quality assurance procedure to reduce the testing time is also available (see 9.3.2). If the results are shown to vary by less than ±2 °C between the different heating rates, use Method B (see 9.3.3).
9.3 Operation
9.3.1 Method A — Rate-dependent results Mount the specimen into the instrument.
Apply a constant rate temperature scan from at least 50 °C below to 50 °C above the transition region(s) of interest at heating rates of 3 °C/min, 5 °C/min and 10 °C/min. Use a new specimen for each heating rate.
The reference test frequency of 1 Hz shall be used.
The load/displacement on the specimen shall be selected so that the specimen deformation is within the elastic range of the material being tested. The applied level shall remain constant to within ±10 % of the initial value applied.
Record the load and displacement data as a function of temperature, so that the storage modulus, loss modulus and tan delta can be calculated and plotted against temperature (see Figure 1). Determine the temperature at the inflection point for the storage modulus curve (see Figure 1. data point 1) at each heating rate.
Plot the temperature of the inflection points as a function of heating rate, as shown in Figure 2. Extrapolate the data to meet the y- axis at 0 °C/min using a linear fit. Report the extrapolated value to 0 °C/min as Tg(o). These data form the calibration curv& shown in Figure 2.
NOTE The determination of the extrapolation value can be aided by an additional scan at 1 CImin, but care is needed if the material state (e.g. degree of cure) changes during the scan.ISO 6721-11 pdf download.