Structure Analyses of a Rubber/Filler System Under Shear Flow by Using Time Resolved Ultra Small Angle X-ray Scattering

The changes in the dispersion of carbon black in liquid isoprene under shear flow with time have been investigated with time-resolved ultra small angle X-ray scattering (USAXS). At the beginning of the experiment, the USAXS profiles have a shoulder at q = 0.07 nm(-1), and the slope is 2.9 at 0.004 nm(-1) < q < 0.01 nm(-1), indicating that aggregates of carbon black with a mean radius of gyration of 14 nm form an agglomerated fractal network structure with a mass-fractal dimension of 2.9. During the application of shear flow, the scattering intensity increases in the whole q-region, and the shoulder reflecting the size of agglomerates shifts to q = 0.005 nm(-1). The analysis by the Unified Guinier/Power-law approach yielded several characteristic parameters, such as the aggregate size, and the mass-fractal dimension. While the mean radius of gyration of agglomerates decrease with increasing time, the mean radius of gyration of the aggregates, the mass fractal dimension, and the surface fractal dimension is constant over time, indicating the aggregates peel off the surface of the agglomerates. (C) 2014, The Society of Polymer Science, Japan