Accession Number : ADA299518
Title : Positron Annihilation Studies of Thermoplastic LCP Composites,
Corporate Author : DUKE UNIV DURHAM NC DEPT OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE
Personal Author(s) : Naslund, Robert A. ; Jones, Phillip L.
PDF Url : ADA299518
Report Date : 03 AUG 1995
Pagination or Media Count : 4
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.
Descriptors : *POLYMERS, *COMPOSITE MATERIALS, *LIQUID CRYSTALS, *THERMOPLASTIC RESINS, *POSITRONS, *ANNIHILATION REACTIONS, SOURCES, LOW TEMPERATURE, RECOVERY, TIME DEPENDENCE, EXPOSURE(GENERAL), HIGH TEMPERATURE, LONG RANGE(TIME), SATURATION, STRENGTH(GENERAL), CONTINUITY, POSITRONIUM.
Subject Categories : Polymer Chemistry
Radiation and Nuclear Chemistry
Laminates and Composite Materials
Nuclear Physics & Elementary Particle Physics
Distribution Statement : APPROVED FOR PUBLIC RELEASE