TGA Measurements of the Vulcanization of NBR
Purpose
To investigate the change in mass during a vulcanization reaction using NBR as an example.
Sample
Unvulcanized NBR with 50% polymer content
Conditions
Measuring cell: TGA/SDTA841e (large oven) coupled to an Inficon ThermoStarTM mass spectrometer
Pan: Alumina 70 µl
Sample preparation: Five pieces, each weighing approx. 10 mg, were cut from the starting material.
TGA measurement: Heating from 35 °C to 300 °C at 10 K/min
Atmosphere: Argon
Evaluation
The TGA curve shows that a loss of mass occurs in the region of interest. The first derivative of the TGA curve (DTG) shows an effect at about 160 °C. DSC measurements on the vulcanization of the materials have already been described in Section 3.1.3. These measurements show that vulcanization takes place between 120 °C and 200 °C (marked by the dashed lines). The total loss of mass in the region in which vulcanization takes place is 0.073%.
A comparison of the DSC curve with the DTG curve shows that the effect in the DTG curve is in fact due to the vulcanization reaction. The loss of mass due to the reaction can be determined by evaluating the peak in the DTG curve (baseline type: Spline). The peak in the DTG curve has an area of 0.073% and a maximum temperature of 161.5 °C.
Conclusions
TGA can be used to determine the small change of mass (less than 0.1%) that occurs in a vulcanization reaction.
TGA Measurements of the Vulcanization of NBR | Thermal Analysis Application No. HB438 | Application published in METTLER TOLEDO TA Application Handbook Elastomers, Volume 2.