Flow Visualisation and Process Image Analysis:

Optical imaging and flow visualisation broadly describe techniques which use imaging systems to monitor some aspect of the process. The IRC laboratories have facilities to carry out process rheo-optical measurements, including a unique co-extrusion flow cell recently produced to allow visualisation of melt layer interfaces. Process imaging has also been used to monitor defects in extruded films and profile, and to monitor the filling of moulded products.

Optical imaging and flow visualisation is of current interest to modelling software companies, raw materials suppliers, high level processors, because this technique can provide detailed validation data for computer modelling, stress and velocity field insights for process geometry design in both extrusion and injection moulding processes, and enhanced understanding of the development of flow instabilities.

Task 3 aims to exploit process imaging techniques to monitor specific aspects of processing, and is split into 3 areas:

1. Surface finish; a novel system to monitor surface finish will be developed
2. Co-extrusion flows will be investigated in detail to further understanding of industrially relevant problems such as wave and zig-zag instabilities, with particular emphasis on industrially relevant thin film problems.
3. Micromoulding; optical imaging of stress birefringence will be applied to this challenging process, using a novel windowed micromoulding cavity, to monitor the stresses generated during filling at high processing rates.