ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Measurements on the thermal expansivity α∥ and α⊥ (along and normal to the draw direction, respectively) have been carried out for a series of oriented polymers with widely different crystallinities (0.36-0.81) and draw ratios (1-20) and over large temperature ranges covering the major amorphous transitions in each case. While α⊥ increases with temperature, α∥ tends to decrease sharply above the transition temperature. For highly crystalline polymers, α∥ decreases to values typical of polymer crystals (-1 × 10-5 K-1) and this can be attributed to the constraining effect of the crystalline bridges connecting the crystalline blocks. However, for polymers of lower crystallinity, α∥ may become an order of magnitude more negative and this remarkable phenomenon is attributed to the rubber-elastic contraction of taut tie-moleucles. Since taut tie-molecules and bridges have drastically different effects on α∥ at high temperatures, this allows a rough determination of their relative fractions.
Additional Material:
15 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1981.180190213
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