New progress in the modelling of stretching flows in a stress-crystallising polymer
The preferred polymer for many transparent thin-walled products requiring biaxial strength and dimensional stability is poly(ethylene terephthalate) (PET). There are continual demands for improved product performance, while minimizing material usage, and process modeling is an important tool in achi...
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| Format: | Conference item |
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2011
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| Summary: | The preferred polymer for many transparent thin-walled products requiring biaxial strength and dimensional stability is poly(ethylene terephthalate) (PET). There are continual demands for improved product performance, while minimizing material usage, and process modeling is an important tool in achieving this. A new study of PET has been carried out, aimed at improving the fidelity of constitutive modeling of this polymer in stretch-forming processes. Several additional refinements have been added to an existing constitutive model used for process modeling with PET. They are based on the results of a recent extensive experimental study of biaxial stretching of PET, under conditions relevant to industrial forming processes. New features now included are: post-yield strain-softening at the lowest temperatures; rate and temperature-dependent flow lock-up associated with incipient crystallization; and tension-thinning flow at the highest temperatures. Comparison of model predictions with experimental results confirm that the additions to the model improve the ability to capture the behavior of PET in biaxial hot-stretching processes. © 2011 American Institute of Physics. |
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