Characterisation of Injection Moulded Polymer Materials using SAXS and WAXS

Abstract

Investigation of the microstructure of polymer materials has been of interest in the recent decades since it defines the mechanical properties of the material. For many commercial applications, understanding the microstructure is key in order to prevent failure and increase quality of the material. This information can also be used to evaluate and modify existing materials and/or design new materials. At Tetra Pak®, packaging solutions for food are constantly developed and improved in order to meet customer’s needs. A long-term goal of the company is to include detailed material structures into their virtual simulations and thus predict mechanical properties with improved accuracy. Polymers are often anisotropic materials of which properties are highly effected by processing conditions and can therefore be difficult to predict. In this master’s thesis, Small and Wide Angle X-ray Scattering (SAXS and WAXS) at both laboratory and synchrotron X-ray sources has been used to study the structure of some semicrystalline polymers used at Tetra Pak® at several different length scales. The scattering data showed that there are several different types of microstructures present in the sample resulting in a layered structure of the material. It was also shown that the microstructure was highly effected both by the position in the sample measured and viscosity of the polymer used. Furthermore, by combining the results from scanning SAXS/WAXS and tensile testing, some links could be established between the material morphology and the mechanical performance of the material.