th - 1988 - 51st ENC Conference
th - 1988 - 51st ENC Conference
th - 1988 - 51st ENC Conference
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1 52 I ~IR STUDY OF NAPHTHALENE TRANSPORT AND P~ELA)LATIOtq IN THE NAPHTHA-<br />
LENE-SUPERCRITICAL ETIIYLENE SYSTEM: K. W. Woo , S. Adamy and J. Jonas, University<br />
of Illinois, Urbana, IL 61801<br />
The purpose of <strong>th</strong>is study is to investigate <strong>th</strong>e motional dynamics of naph<strong>th</strong>alene<br />
in <strong>th</strong>e naph<strong>th</strong>alene-e<strong>th</strong>ylene supercritical mixture using T 1 and diffusion measurements.<br />
The deuterium TI for d,-naDh<strong>th</strong>alene were measure'd along <strong>th</strong>ree iso<strong>th</strong>erms<br />
_ _o . i . o -. . , . f<br />
(lu, 30, 4J C) in <strong>th</strong>e solld-supercrltlcal e<strong>th</strong>ylene ohase at pressures rom i00 to<br />
i000 bar, and along two iso<strong>th</strong>erms (70, 78°C) . from 20-200 bar for <strong>th</strong>e liquid naph<strong>th</strong>a-<br />
lene-suoercritica] e<strong>th</strong>ylene phase. The pressure dependences of <strong>th</strong>e relaxation rate<br />
of d_-naoh<strong>th</strong>alene in <strong>th</strong>e two phases show quite a different behavior. In particu]ar,<br />
tile effect of dissolved e<strong>th</strong>ylene dominates tile motional characteristic of naph<strong>th</strong>alene<br />
in <strong>th</strong>e liquid naph<strong>th</strong>alene phase. In order to complement <strong>th</strong>e data, <strong>th</strong>e diffusion<br />
coefficients of naph<strong>th</strong>alene were also measured using tile fixed-field gradient Bessel<br />
• function analysis technique. The experimental data are interpreted in terms of<br />
current <strong>th</strong>eoretical models. A brief discussion of tlfe potential of i,~ techniques<br />
to orovide unique molecular level information on suDercritical fluid systems is<br />
also included.<br />
NMR CHARACTERIZATION OF THE SOLUTION, GEL AND<br />
153 SOLIDS STRUCTURES OF [(I-3)-~-D-GLUCAN (CURDLAN)]<br />
P. H. Bolton and P. J. Giammatteo*, Wesleyan<br />
University, Middletown, CT and A. J. Stipanovic, Texaco Research<br />
Center, Beacon, NY, 12508<br />
Naturally occuring microbial polysaccharides represent an<br />
important class of compounds whose characteristic properties are<br />
used in applications ranging from foods to enhanced oil recovery.<br />
While typically composed of one to five simple sugars per repeat<br />
unit, polysaccharides can exhibit complex tertiary structure such<br />
as single, double and/or triple helices. Through hydrogen<br />
bonding and/or cross-linking mechanisms, <strong>th</strong>ese systems can form<br />
interchain networks. Fur<strong>th</strong>er, varying degrees of crystallinity<br />
can result depending on bo<strong>th</strong> <strong>th</strong>e monomeric makeup and <strong>th</strong>e<br />
linkages betweeen monomers on <strong>th</strong>e polysaccharide. Depending on<br />
precipitation, hydration and/or solution conditions, Curdlan,<br />
[(l-3)-~-D-Glucan], a linear homopolymer of glucose, can exist in<br />
one of <strong>th</strong>ree distinct solid structures, can form <strong>th</strong>ermally<br />
setting gels, or can exist in ei<strong>th</strong>er a triple or single helix in<br />
solution. CP/MAS 13C NMR was used to study <strong>th</strong>e solid and gel<br />
forms and a variety of 2D solution NMR experiments were employed<br />
to elucidate <strong>th</strong>e molecular conformation,<br />
| • •<br />
self-assoclatlon<br />
mechanism and gel domain structure of Curdlan. All experimental<br />
procedures and applications will be presented and discussed.<br />
175
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