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Viscoelastic modelling of gas pore collapse during polymer sintering

: Wohlgemuth, F.; Alig, I.


Maazouz, A. ; Polymer Processing Society -PPS-; Institut National des Sciences Appliquées -INSA-, Toulouse:
PPS-32. Proceedings : The 32nd International Conference of the Polymer Processing Society - conference papers : Lyon, France, 25-29 July 2016
Melville/NY: AIP Publishing, 2017 (AIP Conference Proceedings 1914)
ISBN: 978-0-7354-1606-2
Art. 190004, 5 S.
Polymer Processing Society (PPS International Conference) <32, 2016, Lyon>
Fraunhofer LBF ()

Based on Frenkel's Newtonian viscous flow approach [1] and Mackenzie and Shuttleworth's [2] extension accounting for trapped gas, a model for the shrinkage of a gaseous pore in a viscoelastic polymer melt driven by surface tension was developed. The viscoelastic flow of polymeric materials was considered by using a simple viscoelastic model described by Bellehumeur [3]. In the simulation, the viscoelastic relaxation leads to a pronounced increase of the characteristic time of shrinkage but does not alter the final equilibrium gas sphere diameter. A first attempt at including gas diffusion into the polymer melt motivated by the works of Kontopoulou and Vlachopoulos [4] and Gogos [5] will be given. Numerical solutions of our simplified model show that gas diffusion leads to a complete collapse of the pore. The rate of diffusion can change the collapse mechanism and the time-dependence of pore radius and pressure tremendously.