Polybutadiene rubbers are used for the fabrication of car tires, wiper blades, gaskets, and other products where the ability to deform and return to the original shape are important. The glass transition temperature is of vital importance to both characterize the material and assess the performance of the final product. Dynamic Mechanical Analysis (DMA) is therefore a great tool to characterize and ensure optimal compound properties of Polybutadiene. Being a rubber, the modulus and the damping properties change dramatically on passing from the glassy to the rubbery state. DMA will show the extent of the change of both the modulus and tan d as the material goes through the glass transition. It will also characterize the glass transition temperature very precisely.
DMA works by applying an oscillating force to the material and the resultant displacement of the sample is measured. From this, the stiffness can be determined and tan d can be calculated. Tan d is the ratio of the loss component to the storage component. By measuring the phase lag in the displacement compared to the applied force it is possible to determine the damping properties of the material. Tan d is plotted against temperature and glass transition is normally observed as a peak since the material will absorb energy as it passes through the glass transition.
Read on in this application note to see the methodology employed and the results and conclusions gained from such DMA experiments using PerkinElmer's DMA 8000 instrument.