DLTMA of Filled Elastomers

Purpose

To investigate the influence of carbon black filled on the Young's modulus of elastomers

Sample

Elastomers based on EPDM with different types of carbon black filler and different carbon black concentrations:

Carbon black: N990 (BET surface area: 9, structure DBP compressed: 40)  

                           N550 (BET surface area: 42, structure DBP compressed: 88)  

Carbon black contents: 21.0%, 34.7% and 44.3%

Conditions

Measuring cell: TMA/SDTA840  

Sample preparation: Cubes with a base area 2 mm x 2 mm and a height of 1.5 mm. A quartz glass disk was placed on the upper side of the sample to distribute the force evenly. 

TMA measurement: DLTMA measurement with a minimum force of 0.05 N and a maximum force of 1 N. The measurement was performed isothermally at 26 °C. The measurement time was 10 min. The period of the force modulation was 0.2 min. A blank curve was subtracted from the measurement curves.

The diagram shows parts of the measurement curves of samples in which N550 carbon black was used as filler. The relative sample thickness is displayed as a function of measurement time. It can be seen that the amplitude is smaller with larger contents of carbon black. It follows that the Young’s modulus increases with increasing filler content.

Evaluation

Young’s modulus was evaluated from the measurement curves. The relationship between the modulus and the carbon black content is shown in the following diagram.

It can be seen that the modulus increases with increasing carbon black content. The strengthening of the material depends on the type of carbon black used. In the case considered, N550 carbon black had the greater surface area. This type of carbon black, used at the same concentration, results in greater strengthening. 

^{DLTMA of Filled Elastomers | Thermal Analysis Application No. HB457 | Application published in METTLER TOLEDO TA Application Handbook Elastomers, Volume 2}