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:
Preoriented isotactic polypropylene was uniaxially drawn at various testing directions and testing temperatures. Change of the molecular aggregation state in amorphous region with extension was elucidated by measurements of melting temperature, enthalpy of fusion, and birefringence at each stage of extension. Melting temperature depends on both crystallite thickness and orientation function of amorphous chains. It is assumed that the enthalpy change of amorphous region takes place when oriented amorphous chains are transformed into random state by heating. The ratio of the enthalpy change of amorphous region in the sample after extension to that in the sample before extension monotonously increased with increasing orientation function of amorphous chains, fa, independent of testing direction and testing temperature. Increase of true stress with drawing led to increase of fa. Increase of fa with extension depended on the testing angle θ between the testing direction and the direction of the crystal c-axis of the preoriented sample, and fa most remarkably increased in extension at θ = 45°.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1982.070270924
