The Influence of the Heating Rate on Oil Content Determination - METTLER TOLEDO

The Influence of the Heating Rate on Oil Content Determination

Purpose

To show the influence of the heating rate on the separation of the vaporization of oil and the pyrolysis of the polymer, using an elastomer based on NR/SBR blend.

In the example considered, the determination of carbon black was not of interest. For this reason, only measurements under nitrogen are presented.

 

Sample

Vulcanized elastomer (sample e) with the following composition:

 

Conditions

Measuring cell: TGA/SDTA851e

Pan: Alumina 30 μl

Sample preparation: Piece of elastomer of approx. 20 mg

TGA measurement: Heating from 50 °C to 625 °C under nitrogen (50 ml/min)

                                   Heating rates: 30 K/min, 10 K/min and 2 K/min 

Atmosphere: Nitrogen

 

Evaluation

 

Interpretation

It is evident that all the effects involving loss of mass are shifted to lower temperatures at lower heating rates. This leads to an improved separation of the individual processes. In particular, a better separation of the oil is achieved. This can be seen from the fact that the content of oil measured increases from 4.6% (at 30 K/min) to 8.4% (at 2 K/min). The latter value agrees well with the formulation (9.1% oil). The improved resolution at lower heating rates also results in a better separation and more accurate determination of the individual polymer components. If the vulcanization system is taken to be 4%, the sum of the polymer content and the vulcanization system of the formulation (36.7%) agrees well with the total step height of the pyrolysis steps (2 and 3) measured at 2 K/min. 

 

Conclusions

A lower heating rate results in a better separation of the different processes – in particular the separation between the vaporization of oils and the pyrolysis of the polymers. This improvement of course means that measurement times are significantly longer. 

 

The Influence of the Heating Rate on Oil Content Determination | Thermal Analysis Application No. HB 480 | Application published in METTLER TOLEDO TA Application Handbook Elastomers Volume 2