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Dependence of Segmental Mobility in Polycarbonate on Time and Deformation

Published online by Cambridge University Press:  16 February 2011

Thor L. Smith  and
Bassel Haidar
Thor L. Smith
Affiliation:
IBM Research Division, Almaden Research Center, San Jose, CA 95120
Bassel Haidar
Affiliation:
Permanent Address: CNRS, Mulhouse, France
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Abstract

Studies are discussed which show that the segmental mobility In polycarbonate (Lexan from General Electric Co.) increases when a static deformation in either extension or simple compression (uniaxial stress) is applied to a specimen, but thereafter the mobility decreases progressively. These changes can be termed erasure (partial) of physical aging (strain softening) and physical aging (hardening), respectively. Because the volume of a specimen deformed in simple compression decreases, reversal of aging (de-aging) cannot be attributed to an increase in free volume, as usually defined. A proposed explanation will be mentioned. A study was also made of the yield stress modified by unconventional methods at several temperatures. The results can be explained In terms of the rate of physical aging and its temperature dependence determined on specimens at 2.6% extension over a broad range of temperatures. These results show that yielding results from progressive de-aging. The yield phenomena obtained by special methods results from both physical aging and de-aging.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 215: Symposium R2 – Structure, Relaxation and Physical Aging of Glassy Polymers , 1990 , 87
Copyright
Copyright © Materials Research Society 1991

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