Structural Changes in Amorphous Poly (Ethylene Terephthalate) Fibers Caused by Combined Heat Mechanical Treatment
Valentin L. Velev1, Anton N. Popov2, Todor N. Dimov3, Hristo Y. Hristov4
1Valentin L. Velev, Faculty of Natural Sciences, Konstantin Preslavsky University, Shumen, Bulgaria.
2Anton N. Popov, Central Scientific Research Laboratory, University “Prof. Dr. Assen Zlatarov” – Burgas, Burgas, Bulgaria.
3Todor N. Dimov, Faculty of Natural Sciences, Konstantin Preslavsky University, Shumen, Bulgaria.
4Hristo Y. Hristov, Faculty of Natural Sciences, Konstantin Preslavsky University, Shumen, Bulgaria.
Manuscript received on 23 March 2015 | Revised Manuscript received on 30 March 2015 | Manuscript published on 30 March 2015 | PP: 1-3 | Volume-4 Issue-1, March 2015 | Retrieval Number: A1328034115©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: The article submits new experimental data pertaining to the role of combined heat-mechanically treatments on the birefringence and degree of crystallinity of amorphous uncrystallized but crystallizable poly (ethylene terephthalate) (PET) filaments. The heat-mechanically treatments of the investigated objects as well as the optical measurements were realized by specialized installations designed and built in the author’s laboratories. Undrawn PET yarns were subjected on heat-mechanically modification at constant temperature of 90 0C above their glass transition temperature (Tg ) combined with tensile stress with values from 0MPa to 30MPa. Birefringence measurements and differential scanning calorimetry (DSC) were used in order to identify the occurred as a result of the heat mechanical processing the specimens’ structural evolution. The optical measurements were carried out using the so called “P-F-A” system involving polarization microscope and a CCD camera. It was established the influence of the superposition “annealing temperature/tensile stress” on the filaments birefringence as well as the dominant effect of the tensile load on the fibers degree of crystallinity.
Keywords: Birefringence, Degree of crystallinity, Fibers, Poly (ethylene terephthalate), Tensile stress.
Scope of the Article: Mechanical Design