DSC Measurements of the Plasticization of SBR

Purpose

To demonstrate the influence of plasticizers on the glass transition temperature measured by DSC, using SBR and an oil as an example.  

Sample 

Solution-polymerized SBR:

Without oil: (VSL 5025-0)

With 37.5% oil: (VSL 5025-1) 

Conditions

Measuring cell: DSC822^e with liquid nitrogen cooling option 

Pan: Aluminum standard 40 ul, pierced lid 

Sample preparation:  Pieces of elastomer of approx. 10 mg

DSC measurement: The samples were cooled to –90 °C at 5 K/min and then measured. Heating from 90 °C to 30 °C at 10 K/min

Atmosphere: Nitrogen

Interpretation

The glass transition temperature of the sample without oil is –19.8 °C. With 37.5% oil, the glass transition temperature decreases to –25.6 °C. The height of the glass transition step, 'cp, is approx. 0.42 J/(gK) and remains unchanged. 

Conclusions

Oil acts as a plasticizer and shifts the glass transition to lower temperatures. In the example analyzed, addition of oil to the elastomer lowers the glass transition temperature by about 6 K. 

_{DSC Measurements of the Plasticization of SBR | Thermal Analysis Application No. HB 483 | Application published in METTLER TOLEDO TA Application Handbook Elastomers Volume 2}