Extreme deformation and adhesion in polymer-metal
laminates
Citation for published version (APA):
Rastogi, R., Vellinga, W. P., Meijer, H. E. H., & Baaijens, F. P. T. (1999). Extreme deformation and adhesion in polymer-metal laminates. Poster session presented at Mate Poster Award 1999 : 4th Annual Poster Contest.
Document status and date: Published: 01/01/1999 Document Version:
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Extreme deformation and adhesion in polymer-metal laminates
R. Rastogi, W.P. Vellinga, H.E.H. Meijer and F.P.T. Baaijens
Eindhoven University of Technology, Faculty of Mechanical Engineering,
Section Materials Technology,
P.O. Box 513, 5600 MB Eindhoven, the Netherlands
Introduction
The mode of adhesion between polymer and the metal in polymer-metal laminates is of crucial impor-tance for the high-tech industrial applications. The polymer does not directly adhere to the metal but re-quires an intermediary metal oxide coating. This lami-nate undergoes processing at high pressures and de-formation rates in very short duration of time, thus stretching the laminate. As a consequence of re-peated processing, new polymer and metal surfaces form at the interface. The metal oxide layer which is extremely thin (5-10nm) probably does not remain continous due to the formation of the new interface area, as shown in the illustration below.
Fig. 1 Schematic representation of laminate before and after stretching.
FEM simulations as described in [1] indicate, high pressure and high strain rates enhance deformation resistance, but they do not take into account these physical changes occurring at the interface. The question remains, which properties of the laminate determine the adherance between the two materials, at the newly formed interface?
Aim
To understand the criteria that determine adhesion between polymer and metal during repeated extreme deformation conditions e.g. wall-ironing.
Experimental approach
✷ To study the properties of polymer and metal un-der high hydrostatic pressure and high strain rates, such as wall-ironing process [1].
✷ Study the morphology of the newly formed inter-face.
✷ Study which types of polymers, when coated on to metal and subjected to severe deformation, still adhere.
Materials studied
PET(Poly-ethylene-terepthalate) coated on ECCS (Electrochemically coated Steel). The metal surface at the interface was studied by etching away the PET coating.
Observations
After repeated processing (wall-ironing) of the lam-inate, the metal surface at the interface was stud-ied. The PET coating was etched away using Phenol and observed under ESEM (Environmental Scanning Electron Microscope) and CLSM (Confocal Laser Scanning Microscope). Each wall-ironing process brings about a change in the surface at the interface as evident from ESEM images. Surface becomes rough and new surface is exposed as in fig. 2 and different modes of metal deformations are shown in fig. 3.
Fig. 2ESEM micrographs of metal surface after PET coat-ing is etched away, showcoat-ing the 4 sucessive stages of Wall-ironing process at lower and higher magnifications.
slip twinning
Fig. 3Different deformation modes of metal.
Conclusions
Results obtained so far show that understanding ad-hesion of the newly formed surface is very important. And also that the roughness and morphology of the interface need more investigation.
References:
[1] VAN DERAA, M.A.H. Wall Ironing of Polymer Coated Sheet Metal Phd thesis, 1999.
