| Summary: | 碩士 === 逢甲大學 === 化學工程學所 === 96 === To observe the entry behavior of oligomeric radicals, the miniemulsion polymerization of styrene was performed, using sodium dodecyl sulfate and fatty alcohol as the mixed-surfactant. Fatty alcohols with different chain lengths were used, and the mole ratios of (SDS/fatty alcohol) are set as 0.5:1, 1:1 and 3:1, respectively.
There are dead-end conversions for the miniemulsion polymerizations, where the conversion can not be raised anymore.
Both values of volume-average diameter (Dv) and the average polymer chain number per particle (np) increase with the concentration of fatty alcohol. And the np value increases with increasing the Dv value. It is possible to observe the difference between the curves shown in the Dv - np plots.
Different particle sizes and distributions were observed for emulsion polymerization dominated by micelles nucleation and those by monomer mini-droplet nucleation.
Capture rate (rc) (i.e., number of radicals captured per unit aqueous phase per time) decreases with increasing the Dv value, and levels-off at a certain value. However, parameter of capture time (tc) (i.e., average time for a radical to be captured per particle), scattered at some range, making it hard to be accepted as a good parameter . Therefor, the rc seems a good parameter for characterizing the entry behavior of radicals into a latex particle in this study.
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