Accession Number : ADA302082

Title :   Molecular Level Characterization by NMR of the Transport and Structural Environment of Gases and Condensed Penetrants.

Descriptive Note : Final technical rept. Jun 91-Sep 94,

Corporate Author : CLARK UNIV WORCESTER MA

Personal Author(s) : Inglefield, Paul T.

PDF Url : ADA302082

Report Date : 25 SEP 1994

Pagination or Media Count : 145

Abstract : NMR measurements have been made on polyisobutylene containihg gaseous and condensed penetrants (CO2 and toluene respectively). Both NMR relaxation and pulse field gradient measurements have been made to characterize both penetrant diffusion and polymer segmental motion simultaneously. The relaxation data are analyzed using conventional models for polymer chain dynamics and the diffusion constants are expressed using free volume theories. It is found that there is a correlation between penetrant diffusion and polymer segmental reorientation. This correlation can be quantified both in terms of timescale and free volume requirements. The unusual slow permeability of polyisobutylene to various penetrants can be rationalized. The data provides a very comprehensive base for critical discussion of segmental chain dynamic descriptions and free volume theories in systems of this type.

Descriptors :   *NUCLEAR MAGNETIC RESONANCE, *GASES, *PENETRATION, *DIFFUSION, *CARBON DIOXIDE, *TOLUENES, REQUIREMENTS, MEASUREMENT, VOLUME, ENVIRONMENTS, MODELS, MOLECULAR STATES, DYNAMICS, STRUCTURAL PROPERTIES, POLYMERS, THEORY, FIELD TESTS, PULSES, CHAINS, RELAXATION, CHAIN REACTIONS, GRADIENTS, FIELD THEORY.

Subject Categories : Physical Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE