ISSN:
0887-6266
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Solid-state coextrusion has been used to prepare uniaxially drawn films from isotropic poly(ethylene 2,6-naphthalate) (PEN) of a minimum degree of crystallinity (ca. 5%) both below and above its glass transition temperature Tg. The onset of cold crystallization (Tc) of the drawn films has been studied as a function of the extrusion temperature (ET) and the draw ratio (EDR). It has been shown that Tc decreases markedly on draw, as much as 95°C, and, at constant draw ratio Tc goes through a minimum in the Tg region. For undrawn PEN, annealing below 153°C has no significant effect on Tc. To evaluate the crystallization rate constant (k) and the activation energy (Ea) of the drawn specimens, a nonisothermal DSC procedure has been used. With increasing EDR, k increases markedly and Ea goes down over threefold compared with the undrawn polymer. At high ET, strain-induced crystallization has also been shown to play an important role in lowering Ea for cold crystallization. Thermal shrinkage above Tm indicates a high elastic recovery, underlining the efficiency of deformation, ca. 93%, achieved by solid-state coextrusion.
Zusätzliches Material:
16 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/polb.1989.090271303
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