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Biaxially Oriented PP Films Using the Double Bubble Process

  • H. Benkreira and M. C. Talford
Published/Copyright: June 5, 2013
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Abstract

Biaxially Oriented Polypropylene (BOPP) film has become an increasingly important commodity over the last 30 or so years, offering an alternative to more traditional cellulose films with much improved mechanical and optical properties. The process is similar to the traditional bubble process for manufacturing films from a polymer melt, and the main difference in modelling the two processes lies in the constitutive equation employed. As the manufacturing process involves large strain deformations, a convected Standard Linear Solid constitutive equation was used in conjunction with the Pearson and Petrie force balance equations and a suitable energy balance to arrive at a mathematical model of the double bubble process. The non-linear ordinary differential equations forming the model require simultaneous solution, carried out using numerical techniques. An experimental program was conducted to obtain large-scale biaxial tensile test data. This data was used to determine the necessary material properties required to allow the model to be applied to a particular commercial process. Material data not obtained thus far has been estimated using previously published data for similar materials. Operating data was obtained from a fully instrumented full-scale industrial bubble process to enable the model to be validated. Initial comparisons between the model results and process data suggest that the model developed is a good starting point for a process simulation but that more accurate material data is required.


* Mail address: H. Benkreira, School of Engineering, University of Bradford, Bradford, BD7 1DP, UK

Received: 2002-4-22
Accepted: 2002-6-27
Published Online: 2013-06-05
Published in Print: 2002-09-01

© 2002, Carl Hanser Verlag, Munich

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