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Handbook of Size Exclusion Chromatography and Related ...

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each sample. Both proton <strong>and</strong> carbon-13 NMR analyses indicated that the lost mass<br />

was converted to the low MW degradation products. It appears that the hydrolysis <strong>of</strong><br />

AM <strong>and</strong> chain scissoring <strong>of</strong> the polymer chains occurred during the heating process<br />

in an autoclave. The molecular weight <strong>of</strong> the degradation product is lower<br />

than the separation limit (MW is about 600 g/mole) <strong>of</strong> the columns at the low<br />

molecular end.<br />

4.2 For Cationic Acrylamide Polymers<br />

4.2.1 Providing a Guideline for Process Development in the<br />

Polymer Synthesis Area<br />

Studying Structure/Performance Relationship. Figure 9 shows the<br />

chromatogram <strong>of</strong> two precipitated samples <strong>of</strong> AM/AA/DMDAAC emulsion<br />

terpolymers. The high MW <strong>and</strong> narrow peak width in chromatogram (1) is<br />

due to crosslinked species in the sample. The same phenomenon is not<br />

observed in chromatogram (2). This structure difference leads to different<br />

behaviors in a paper industrial application. The partially crosslinked terpolymer<br />

performs well <strong>and</strong> the noncrosslinked terpolymer performs poorly. Based on this<br />

information, a crosslinking agent may be added during the polymerization<br />

process to modify the structure until the desired structure is obtained.<br />

Figure 9 <strong>Size</strong> exclusion chromatograms <strong>of</strong> two precipitated AM/AA/DMDAAC<br />

emulsion terpolymers: (1) partially crosslinked terpolymer; (2) noncrosslinked terpolymer.<br />

© 2004 by Marcel Dekker, Inc.

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