Use of computational fluid dynamics to improve the layer thickness control of polyester based multilayered films

Champion, James (2015). Use of computational fluid dynamics to improve the layer thickness control of polyester based multilayered films. University of Birmingham. Eng.D.

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Abstract

Multilayered films are formed via coextrusion when separately extruded polymer melt streams come together in either an injector block linked to a die or a multi-manifold die. As multilayered film structures increase in complexity it becomes more difficult to control the individual layer thickness control, STAR-CCM+ computational fluid dynamics software was used to model both coextrusion geometrics and polymer melt flows.

The comparative ability of the injector block and multi-manifold die systems to handle increasingly wide melt viscosity ratios was investigated numerically. It was found that the multi-manifold die was the better option when producing films with wide melt viscosity ratios.

Experimental validations using die plug analysis, chloroform washing, light microscopy and white light interferometry were conducted to test the accuracy and relevance to reality of the numerical results. Excellent agreement was generally found between both experimental and numerical data. The good agreement between experimental and numerical results was used to predict the outcome of two pilot trials.

Using computational fluid dynamics, it was found that the pilot edge heaters are located too far from the edges to improve the thickness profile here. However, on a production scale multi-manifold die the film edges significantly improved.

Type of Work:

Thesis (Doctorates > Eng.D.)

Award Type:

Doctorates > Eng.D.

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