ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Log-normal particle size distributions in polymer solutions have been measured with the Coulter counter. Qualitative membrane diffusion measurements were performed to substantiate the presence in these solutions of particles in the micron size range. Particle size was found to be dependent upon the thermal history of a polymer solution and upon the shearing forces to which it had been subjected. Further, particle size decreased upon dilution of a polyelectrolyte solution or upon an increase in the salt content. It is concluded that polymeric aggregates are the species being counted. These aggregates apparently originated during the polymerization of the polystyrene or of the styrene maleic anhydride studied. Bimodal distributions were observed in polystyrene solutions and in polystyrene sulfonate (Na+) solutions. The latter bimodal systems were resolved by graphical means, and it was found that the two populations are present in the ratio 65:35. The two distributions have the same dispersions (0.04) and only slightly different means (3.7 versus 4.5 microns). The mechanism of formation of this bimodal system may be that proposed by van der Hoff; namely, that particles are formed consecutively in the micellar and in the aqueous phase of an emulsion polymerization system when the soap concentration is near the critical micelle concentration.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1963.100010201
