Correlation of Electrical Conductivity and Radiation-Induced Free Radical Concentration in Poly(Ethylene Terephthalate) and Related Compounds

This report describes a research effort concerning the electronic processes in irradiated poly(ethylene terephthalate), PET, and two model compounds. The radical concentration in PET is shown to build up continuously as the gamma-dose or UV light exposure is increased. Three different radicals are i...

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Bibliographic Details
Main Authors: Monteith, L. K, Turner, D. T, Ballard, L. F
Format: Report
Language:English
Subjects:
BULK SEMICONDUCTORS
CARRIER MOBILITY
CORRELATION
CRYSTALS
DECAY
ELECTRICAL CONDUCTIVITY
Electricity and Magnetism
ELECTRONICS
ESTERS
ETHYLENE GLYCOL
EXPOSURE(GENERAL)
FREE RADICALS
IRRADIATION
KINETICS
LIGHT
METHYL RADICALS
MOLECULAR STRUCTURE
OPTICAL PROPERTIES
OXYGEN
PET(POLY(ETHYLENE TEREPHTHALATE))
PHTHALATES
Physical Chemistry
POLARIZATION
POLYETHYLENE TEREPHTHALATE
Polymer Chemistry
QUENCHING
RADIATION
RADIATION ABSORPTION
Radiation and Nuclear Chemistry
SAMPLING
SURFACE PROPERTIES
TRANSIENTS
ULTRAVIOLET RADIATION
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Summary:This report describes a research effort concerning the electronic processes in irradiated poly(ethylene terephthalate), PET, and two model compounds. The radical concentration in PET is shown to build up continuously as the gamma-dose or UV light exposure is increased. Three different radicals are identified by ESR spectra. The relative concentration of each radical depends upon the degree of crystallinity of the sample. The optical absorption near 3100 A and the electrical conductivity of irradiated samples are tied directly to the radical concentration. This is demonstrated by observing the rate of buildup of each effect and the kinetics of radical decay and conductivity decay at various temperatures. The quenching effect of oxygen is also shown to be similar for radical concentration, optical absorption, and electrical conductivity. Carrier mobilities are measured for PET and molecular crystals of dimethyl terephthalate and dibenzoate ester of ethylene glycol. The mobility of the molecular crystals is observed to decrease significantly after exposure to gamma-rays. Bulk and surface polarization effects are observed to play a dominant role in transient electronic behavior. jg p2