Successful PhD Defence for Dirk Grommes

The supervisors and reviewers were Prof Dr Dirk Reith from H-BRS and Prof Dr Wolfgang Imhof from the University of Koblenz. In addition, Prof Dr Christian Fischer (also from the University of Koblenz) was a member of the examination board for the final oral examination. The work was supported by a doctoral scholarship from the Dr Reinold Hagen Foundation. 

If you were to explain it to a non-specialist in 3-5 sentences: What were the main results of your doctorate?

‘The exciting question of my research was how it is possible to simulate at least parts of a complex plastics processing procedure - specifically extrusion blow moulding for the production of bottles and canisters of all kinds - on a microscopic level on the computer. For this purpose, the method of molecular dynamics (MD) simulation was used to model the plastic polyethylene in its (almost) atomistic structure in simulation calculations.

The results show that it is possible to determine material characteristics that can otherwise only be determined experimentally by using MD simulations. These include important parameters in engineering applications such as the modulus of elasticity, the yield stress or the coefficient of thermal expansion. At the same time, it was possible to demonstrate the micromechanical behaviour of the polymer chains during processing. The observed interplay of orientations of polymer chains and their interconnections explains the formation of microstructures, in particular crystalline areas. The results enable a deeper understanding of the interpretation of locally occurring effects during plastics processing.’

What are your career plans for the near future?

‘I would like to stay in science in the future and continue to be actively involved in research projects as well as teaching. This means that I will remain at the university after completing my doctorate. On 1 September, I started my post-doc position in the ‘AdTTSWes’ research project with Prof Christian Dresbach at the Rheinbach site. There I will be able to work experimentally and via finite element simulation on the adhesion and delamination behaviour of transdermal therapeutic systems. But molecular dynamics simulation will also continue to play a daily role for me in close contact with Dirk Reith.’