In-Situ Studies of Polymer Processing for Optimised Structure and Properties

Abstract

The transformation from a molten polymer to a crystalline solid product is a complex process. We show how special x-ray/rheology tools can be used to follow the development of structure during flow and the subsequent crystallization process and to identify the critical steps in this transformation. We have found that time-resolving x-ray scattering studies are a valuable approach, especially when coupled with other in-situ techniques such as neutron scattering and ex-situ methods such as electron microscopy.  We illustrate the use of these tools with a study of the crystallization of polyethylene blends after being subject to shear flow in the melt. The resultant crystal textures and hence properties are strongly dependent on the shear strain imposed in the melt. High shear strain in the melt leads to a high density of row nuclei which serve to template the subsequent crystal growth.  The microscopy on the final samples provides a complementary technique which offers valuable information on the spatial distribution of the morphology.