Temperature-Dependent DMA Measurements of an Unfilled SBR/NR Elastomer - METTLER TOLEDO

Temperature-Dependent DMA Measurements of an Unfilled SBR/NR Elastomer

Purpose

The mechanical behavior of an unfilled elastomer blend is measured using an SBR/NR blend as an example.

 

Sample

Elastomer based on a blend of 40% NR and 60% L-SBR vulcanized with 2 phr sulfur. 

 

Conditions

Measuring cell: DMA/SDTA861 with shear sample holder  

Sample preparation: Cylinder of 6-mm diameter punched out from a 1.6-mm thick film and mounted in the shear sample holder with 10% predeformation.  

DMA measurement: The measurement was performed with a frequency series of 1, 10 and 100 Hz and a heating rate of 2 K/min in the temperature range –90 °C to 100 °C. Maximum force amplitude 5 N, maximum displacement amplitude 10 Pm, offset control zero. 

 

Interpretation

The DMA curves show the glass transition of NR in the temperature range –60 °C to –40 °C. The storage modulus changes by about 0.6 decades. The glass transition of SBR then occurs from about –30 °C onward and Gƍ decreases by about 3 decades. In contrast to the step heights of glass transition in DSC curves, it is not possible to directly estimate the relative proportions of the individual components from the step heights. The reason for this is that after the glass transition of the NR the material consists of hard and soft regions. The modulus of such blends can be described by different models. 

The tan 𝛿 curve shows that the damping behavior of an elastomer can be significantly changed through the use of incompatible polymer blends. The SBR/NR blend measured exhibits larger damping at low temperatures than the pure SBR elastomer. The material properties can therefore be optimized by using blends of specific composition. 

 

Conclusions

DMA measurements can be used both for the analysis of elastomers and for the optimization of the properties of materials. The damping behavior of materials can be optimized by choosing a suitable composition of the blend

Temperature-Dependent DMA Measurements of an Unfilled SBR/NR Elastomer | Thermal Analysis Application No. HB 476 | Application published in METTLER TOLEDO TA Application Handbook Elastomers Volume 2