Using Coherent Small Angle Xray Scattering to Measure Velocity Fields and Random Motion

The dynamics of cross-linked polymers under stress, such as those that make up rubber, are still not well understood. A combination of coherent xray homodyne and heterodyne techniques is used in order to measure fluctuations of the system when stretched. The combination of both techniques allows for the measurement of flow patterns, as well as the random nature of the system. After data analysis, the results show that the measurements successfully captured this flow information. The flow velocity was discovered to have a time-dependent nature similar to that of the stress-strain curve. After the flow velocity was extracted, the random nature of the system was analysed. This random motion was discovered not to be dominated by conventional diffusion, but some slower random process.