Abstract:Physical aging of semicrystalline polyethylene terephthalate was studied using differential scanning calorimetry(DSC). PET samples with crystallinity content of 0.28 were aged at two different temperatures, 25 and 45°C. Thesamples were stored for several days and periodically tested using DSC method. The glass transition temperature forthe samples aged at 25°C was about 73-74°C, and the position and intensity of endothermic peaks wereapproximately constant. Higher glass transition of the samples aged at 45°C, … Show more
“…The system seems to rearrange to recover some crystallinity, resulting in an equilibrium state after a few days. Similar behaviour has been observed in other works, although with either a different polymer or items (Farhoodi et al, 2012; Song et al, 2016). )Fig.…”
“…The system seems to rearrange to recover some crystallinity, resulting in an equilibrium state after a few days. Similar behaviour has been observed in other works, although with either a different polymer or items (Farhoodi et al, 2012; Song et al, 2016). )Fig.…”
“…Farhoodi et al investigated the physical aging process at 25 °C and 45 °C. No changes were observed at lower temperatures, while the higher temperature allowed for the observation of the relaxation processes in the material [ 10 ].…”
Section: Introductionmentioning
confidence: 99%
“…Sato and Sprengel studied the dynamics of the relaxation process below the glass transition temperature and determined the constants of individual relaxation processes [7]. Farhoodi et al investigated the physical aging process at 25 • C and 45 • C. No changes were observed at lower temperatures, while the higher temperature allowed for the observation of the relaxation processes in the material [10].…”
The influence of the thermo-oxidative aging semi-crystalline polyethylene terephthalate process on the thermal and mechanical properties was analysed in the article. For this purpose, PET was aged at 140 °C for 21, 35 and 56 days. The research showed that as a result of aging, the amount of the crystalline phase increases by about 8%, which translates into the properties of the aged material. The glass transition and melt temperature of lamellar crystals formed during first and second crystallisation increase with aging. The mechanical properties of the material were analysed in the temperature range of 25 to 75 °C. The tests were showing an increase in Young’s modulus and a decrease in elongation at the break as a result of aging. This phenomenon was particularly visible during tests at 75 °C and during the morphological observation of the fracture surface, where the fracture character of the material changes from ductile to brittle. In the case of the material aged for the longest time, the temperature has a negligible influence on the elongation at break.
“…Jing and Shanyuan [ 7 ] analyzed the modulus–strain curve of poly(ethylene terephthalate) and polyamide yarns in relation to physical structure change. Farhoodi et al [ 8 ] studied the physical aging of semi-crystalline poly(ethylene terephthalate) at different aging temperatures using differential scanning calorimetry (DSC). The study signifies that the crystallization process of polymer chains can be enhanced as the aging temperature increases.…”
Textile materials produced from a high tenacity industrial polyester fiber are most widely used in the mechanical rubber goods industry to reinforce conveyor belts, tire cords, and hoses. Reinforcement of textile rubber undergoes a vulcanization process to adhere the textile materials with the rubber and to enhance the physio-mechanical properties of the product. The vulcanization process has an influence on the textile material being used as a reinforcement. In this work, the effects of aging temperature and time on the high tenacity polyester yarn’s mechanical and surface structural properties were investigated. An experiment was carried out on a pre-activated high tenacity polyester yarn of different linear densities, by aging the yarn specimens under various aging temperatures of 140, 160, 200, and 220 °C for six, twelve, and thirty-five minutes of aging time. The tensile properties and surface structural change in the yarns pre- and post-aging were studied. The investigation illustrates that aging time and temperature influence the surface structure of the fiber, tenacity, and elongation properties of the yarn. Compared to unaged yarn, an almost five times higher percentage of elongation was obtained for the samples aged at 220 °C for 6 min, while the lowest tenacity was obtained for the sample subjected to aging under 220 °C for 35 min.
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