ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A new technique was developed to study the molecular mechanics of highly oriented polypropylene during stress relaxation and creep. The polarized infrared spectrum was recorded while the polymer was under load. Stress relaxation effects were investigated during the two-stage process of fast decay followed by a slower “dynamic equilibrium” decay by examining the stress-sensitive 975-cm-1 band and the orientation-sensitive 899-cm-1 band. In the fast decay region, the aligned chains became more highly overstressed and the nonaligned chains quickly relieved themselves of their initial overstress. These findings suggest an exchange of stress from nonaligned to aligned chain segments, without much orientation change. Also, a rupture of very highly overstressed aligned chains is though to occur. In the slow decay region, the aligned overstressed chains showed a relief of stress accompanied by some disorientation or helix distortion. Creep, however, appeared to occur via a process which involved all chains regardless of alignment. It was found that the number of highly stressed bonds increased with time at the expense of the intermediately stressed bonds. Very little change in overall orientation was noted, which probably explains the observed crazing and void formation.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1974.180120806
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