ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Density gradient sedimentation of polystyrenes, Hevea rubber and synthetic cis-1,4-polyisoprene was studied in the systems ethylene bromide-mesitylene and (1,2-dibromo-1,1-difluoroethane)-cyclohexene. The latter system has very closely matched refractive indices at atmospheric pressure. This work was oriented toward the analysis of mixed polymer and copolymers. Large density gradients were used with schlieren optics. No difference between the points of accumulation of polystyrene from different types of polymerization nor between Hevea and cis-polyisoprene could be found under the conditions employed. Narrow gradient patterns could be produced for polymers of Mv = 200,000. These broadened with increasing polymer concentration. At M = 106 it is believed to be possible to estimate semiquantitatively concentrations of polystyrene of 5 ppm. A method of estimating the amount of a component present in terms of its gradient pattern is given. The density distribution in the bromofluoroethane system was studied by the use of inert marker substances of known density.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1963.070070118
