ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The application of the sand columm extraction, fractional coacervation, and coacervate extraction methods to the molecular weight fractionation of polypropylene is described. Extremely reproducible results are given by the sand column method, and ten fractions taken by this method are adequate for characterization of the usual polypropylene distribution. The variation between the molecular weight distributions derived from six fractionations of a test polypropylene by the three methods was small and indicates that fraction polydispersity probably contributes negligibly to any deviation of the experimental distributions from the true distribution. Polypropylenes made with aluminum triethyl-transition metal trichloride catalysts contain relatively large amounts of low molecular weight polymer and have broad distributions similar to that of low-pressure polyethylene. All such polypropylene samples had distributions which were described well by a logarithmic normal equation with a constant standard deviation. The distribution was not altered when the aluminum triethyl in the catalysts was replaced by aluminum triisobutyl. Catalysts containing vanadium as the transition metal, however, produced polypropylenes with distributions distinctively different from those made with titanium trichloride.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1961.1205015323
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