Mapping Orientation Distribution of Talc Particles in Polypropylene by Small-Angle X-ray Scattering Tomography

Abstract

Small-angle X-ray scattering tomography has for the first time been used toinvestigate the spatially resolved orientation distribution of talc particles in asample of injection molded isotactic polypropylene, where the particles had apreferred orientation along the axis of the injection. The scattering patternsin the direction perpendicular to the rotation axis of the tomography scanwere used to retrieve the orientation distribution in a 2D cross section of thesample.Two different methods are presented, one using a numerical approach ofsimulated annealing and one method using a linear set of equations to findthe distances the X-ray beam travels through the different orientation regions.The method of simulated annealing showed little to no promise inretrieving the orientation distribution while the method using a linear setof equations is successful at retrieving the main features of the orientationdistribution. The resolution is however not yet good enough to distinguishfine details inside the sample.It is believed that with further work on the model used and additional constraintson the reconstruction algorithm higher precision in the retrievedorientation distribution can be achieved.