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1999 | 95 | 4 | 496-504
Article title

Polypropylene Films Studied with Variable Positron Beams

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EN
Abstracts
EN
Doppler broadening and positron lifetime spectra have been measured for polypropylene films of constant thickness (≈ 50 μm) and different morphology that crystallized from melt at temperature 0, 100, and 120°C. The S -parameter vs. energy curves do not change in a systematic way with crystallinity of samples. It is supposed that decrease in the fractional free volume for samples of greater crystallinity is not seen in S-values because of their increase resulting from annihilation in defects present both in the crystalline regions and on the lamellae surfaces. Intensities of the components in the positron lifetime spectra: I_{2} (τ_{2}=1.3 ns) and I_{3} (τ_{3}≈ 2.3÷2.8 ns) show changes with crystallinity of samples. The evident trend is observed for the longer-lived τ_{3}-component intensity to decrease with crystallinity while the reverse is true for the shorter, fixed τ_{2}-component. The decrease in the intensity of the longer-lived component can result from reduction of the fractional free volume.
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Contributors
author
  • Institute of Experimental Physics, University of Wrocław, Pl. Maksa Borna 9, 50-204 Wrocław, Poland
author
  • School of Physics, University of East Anglia, Norwich NR4 7TJ, United Kingdom
author
  • Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
References
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Publication order reference
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YADDA identifier
bwmeta1.element.bwnjournal-article-appv95z410kz
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