ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Partially oriented polyesters yarns (POY) were strained at different strain rates (0.03-12.00 min-1) and temperatures above and below Tg (3-92°C). Thermal retraction, density, DSC, and WAXS techniques show that strain-induced crystallization takes place by straining at temperatures above as well as below Tg. Above Tg, depending upon the strain rate, two regimes are observed: Below the strain rate of 1.5 min-1, the flow regime; the degree of crystallinity is reduced as the strain rate increases. Above the strain rate of 1.5 min-1, the strain-induced crystallization regime; the degree of crystallinity increases as the strain rate increases. Thermal retraction, stress-relaxation, and sonic modulus techniques indicate that, upon cold straining, instead of the original Tg at 65-69°C, two glass transitions occur: an upper Tg (u) and a lower Tg (l). For POY strained at 3°C and at a strain rate of 10 min-1, the values are 78°C and 37°C, respectively. The higher the strain rate and the lower the straining temperature, the large the difference between Tg (u) and Tg (l).
Additional Material:
15 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1982.070270703
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