Positron Annihilation Studies of Thermoplastic LCP Composites,

Abstract

The time-dependent decrease in ortho-positronium (o-Ps) intensity detected in polymers during long-term positron annihilation lifetime (PALS) experiments has been extensively studied and modeled. This decrease in temperature dependent, polymer specific, source strength dependent and is noted to saturate as a function of source exposure time. Larger decreases and smaller saturation values are exhibited at lower temperatures. Additionally, at sufficiently high temperatures, a negligible decrease is detected. The time dependent decrease is recoverable at elevated temperatures. In contrast, the o-Ps lifetime component remains constant and independent of exposure time. Increasing the exposed sample volume by continuously varying the source-sample orientation dramatically decreases the reduction of o-Ps intensity.

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Document Details

Document Type
Technical Report
Publication Date
Aug 03, 1995
Accession Number
ADA299518

Entities

People

  • Phillip L. Jones
  • Robert A. Naslund

Organizations

  • Duke University

Tags

Communities of Interest

  • Human Systems

DTIC Thesaurus Topics

  • Biomedical And Dental Materials
  • Chemistry
  • Composite Materials
  • Contrast
  • Electrons
  • Free Electrons
  • Free Radicals
  • Intensity
  • Materials
  • Materials Science
  • Polymer Chemistry
  • Polymers
  • Polypropylene
  • Positronium
  • Positrons
  • Saturation
  • Thermoplastic Composites

Readers

  • Materials Science and Engineering.
  • Mathematics or Statistics
  • Medical Imaging.