Evolution of nanometer voids in polycarbonate under mechanical stress and thermal expansion using positron spectroscopy
Article first published online: 11 MAR 2003
Copyright © 1995 John Wiley & Sons, Inc.
Journal of Polymer Science Part B: Polymer Physics
Volume 33, Issue 1, pages 77–84, 15 January 1995
How to Cite
Xie, L., Gidley, D. W., Hristov, H. A. and Yee, A. F. (1995), Evolution of nanometer voids in polycarbonate under mechanical stress and thermal expansion using positron spectroscopy. J. Polym. Sci. B Polym. Phys., 33: 77–84. doi: 10.1002/polb.1995.090330109
- Issue published online: 11 MAR 2003
- Article first published online: 11 MAR 2003
- Manuscript Accepted: 5 JUL 1994
- Manuscript Revised: 22 JUN 1994
- Manuscript Received: 19 OCT 1993
- positron lifetime;
- free volume;
Positron Annihilation Lifetime Spectroscopy (PALS) measurements were conducted on polycarbonate subjected to either thermal expansion or to tensile and compressive strains. It was found that thermal expansion affected both the nanometer hole size and the hole number density, whereas mechanical stress affected mainly the size of existing holes, and did not generate or eliminate holes in the quasielastic deformation region. The effect of stress on yield and postyield behavior of this glassy material was also investigated. The deduced hole volume fraction of this polymer at 25°C was 6.8 ± 0.5% from the thermal expansion experiment and 7.2 ± 1.2% from the mechanical loading experiment. When the specimen was under compression, the hole volume fraction was found to continuously decrease. This can be considered as evidence of the inability of the free volume concept in explaining the yield behavior of glassy polymers. ©1995 John Wiley & Sons, Inc.