| This research focuses on the control of morphology via the equal channel angular extrusion (ECAE) process in both semi-crystalline and amorphous polymers. The need for establishing functional correlations between ECAE mechanics, structural evolution, deformation mechanism(s), and the corresponding physical/mechanical property enhancement due to the novel ECAE process in polymers constitutes the broad focus of this work. Linear low-density polyethylene (LLDPE) and polycarbonate are chosen as model systems due to their distinct orientation mechanisms. An integrated die was designed and built to perform the extrusion. The applicability as well as the effectiveness of the current applications were then evaluated. The present study indicates that the ECAE process is effective in producing a high degree of simple shear plastic deformation throughout the extruded polymer plaques. Such high degree of plastic deformation induces a high level of uniform molecular and/or microstructure orientation across the extruded polymer plaques. As a result, significant improvement in both physical and mechanical properties of the polymers is expected. It is revealed that the induced anisotropy can be well described by the corresponding stress-strain state. The extruded polymer parts are analyzed using a series of microscopy and spectroscopy techniques to correlate the explicit mechanical behavior with the oriented molecules, and to provide a fundamental understanding of the deformation mechanisms associated with the morphological evolution due to the ECAE process. The present study provides a useful insight in revealing macro- and micromolecular structure-property relationships of oriented polymers. |
