ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
By emulsion polymerization at 55°C., samples of styrene-divinylbenzene copolymer were prepared, whose content of divinylbenzene varied from 0 to 0.150%. Measurements of intrinsic viscosity and of the slope constants β and k′ were made, at 25.0°C. in butanone and in benzene, of these samples and of fractions obtained from them by fractional precipitation. In both solvents the intrinsic viscosity of unfractionated polymer was at a maximum at a divinylbenzene content of about 0.005% and k′ was at a maximum at about 0.10%. Since the gel point was also in the neighborhood of 0.10%, it is concluded that a maximum in k′ is a better indication of the gel point than a maximum in [η]. As with linear polymers, [η] was smaller and k′ larger in the poorer solvent. For the higher fractions of a given lightly cross-linked sample, k′ increased with increasing intrinsic viscosity, deviating progressively more from the value (0.40 in butanone) characteristic of the low fractions and of linear polystyrene. This progressive deviation appeared to begin at an intrisic viscosity which for different samples decreased with increasing proportion of divinylbenzene. These effects are accounted for qualitatively in termas of Baker's “microgel” concept and the effects of the two solvents on the dissolved molecules and dispersed microgel particles.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1952.120090308
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