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Handbook of Size Exclusion Chromatography and Related ...

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17<br />

<strong>Size</strong> <strong>Exclusion</strong><br />

<strong>Chromatography</strong><br />

<strong>of</strong> Low Molecular<br />

Weight Materials<br />

Shyhchang S. Huang<br />

Noveon, Inc.<br />

Brecksville, Ohio, U.S.A.<br />

1 INTRODUCTION<br />

Low molecular weight (MW) polymers, or oligomers, have been used as<br />

plasticizers, detergents, lubricants, food additives, <strong>and</strong> prepolymers for<br />

copolymerizations. The MW distribution <strong>of</strong> these materials is an important<br />

parameter for their performance.<br />

Common MW determination methods, such as light-scattering<br />

photometery, membrane osmometry, <strong>and</strong> ultra-centrifuge, do poorly with low<br />

MW oligomers because <strong>of</strong> their low sensitivities. Low MW oligomers are<br />

normally analyzed by colligative property measurements, such as vapor phase<br />

osmometry, boiling-point elevation (ebulliometry), freezing-point depression<br />

(cryoscopy), end group analyses by titration, <strong>and</strong> by various spectroscopic<br />

techniques. All these methods only generate one number-average MW (Mn)<br />

<strong>and</strong> are normally time consuming (1). The recently developed technique <strong>of</strong><br />

© 2004 by Marcel Dekker, Inc.

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