Accurate constitutive modeling of polymeric fibers presents a difficult and distinct
challenge. While significant progress has been made in constructing models
applicable for small strains and limited strain-rate and temperature regimes, much
less has been made for more general conditions. This is due in part to the
complexity of polymeric behavior. In this work, experimental results of uniaxial
extension tests on Polyethylene terephthalate (PET) were obtained from Dr.
S.Bechtel, were analyzed, and were formulated into a new model which explains
the behavior of PET at different temperatures and strains. The biggest impediment
in the determining the behavior of polymeric was the difference in the behavior of
PET above and below its glass transition temperature. Consequently, well
established (from microstructural considerations) constitutive models and concepts
for rubber elasticity and plasticity were not directly transferable to modeling PET
fibers. In the model, the PET fibers were assumed to be constituted by amorphous
and crystallization segments and the response of the material during stretching was
the combined response of simultaneous stretching of the amorphous and the crystalline segments. The strengthening mechanism is due to orientation of the
amorphous segments during stretching. The model involves a friction element
which took account of the plastic behavior below the glass transition temperature.
The model was used to predict the response of PET at different temperatures and
the results from the model showed good agreement with the experimental data. The
results from the research will be further used to increase the overall efficiency of
the fiber drawing process.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/5763 |
| Date | 17 September 2007 |
| Creators | Yadav, Seemant |
| Contributors | Srinivasa, Arun |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 537003 bytes, electronic, application/pdf, born digital |
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