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:
A drawn PET yarn was heat set (annealed) at temperatures between 110°C and 245°C in an unconstrained mode and the samples characterized by dynamic mechanical analysis (DMA). A method for estimating the fiber orientation factor (α) is proposed using DMA and shown to be more sensitive than the crystalline orientation (x-ray diffraction) or total orientation (birefringence) measurements of the heat set yarns. The extension/shrinkage behavior of the heat set yarns has been discussed in the light of morphological changes, e.g., degree of orientation and the micro-crystallite formation. Unlike in the unconstrained mode, heat setting under constraint does not lead to the formation of micro-crystallites as revealed by differential scanning calorimetry. As a consequence, although the modulus and degree of orientation increase upon constrained annealing, the thermal stability, i.e., loss of orientation (reflected by shrinkage) could not be improved.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1991.070420314
