ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Differential scanning calorimetry (DSC) studies show that poly(ethylene oxide) (PEO) exhibits three transition regions below its melting point. The effects of annealing on the intensity and temperature of these transitions enable us to locate T 〈 Tg (Tγ) Tg, and Tα at about 130-140. 190-240, and 263-313°K, respectively. Our results argue for a small transition Tg (L) at 190-200°K with a second Tg (U) above 233°K, the temperature of which increases on annealing. The shape of DSC derivative curves reveals that T 〈 Tg and Tα are complex and suggests the possibility of two steps in these processes. In addition, a splitting of Tα is observed every time a multiple melting endotherm appears as a result of annealing. Up to three separate melting endotherms can be observed. One of them is related to the normal primary crystallization process. Its peak temperature increases linearly with the annealing temperature, yielding an extrapolated value for the equilibrium melting temperature T0m of 347°K as found before.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1977.180150801
