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:
Measurements of the density of a large number of experimental isotactic polypropylenes have shown that the specific volume is linearly related to per cent crystallinity as determined from x-ray data. The density is also linearly related to the absorbance of certain absorption bands in the infrared spectrum of isotactic polypropylene. The infrared data allow a determination of the density of the amorphous polymer which is in good agreement with literature values and with a value determined from the x-ray data by extrapolation to zero crystallinity. It is found that there is a rough, approximately linear correlation between crystallinity (by density) of unextracted polypropylene and the per cent insoluble residue remaining after extraction with boiling n-heptane or after successive extraction with other solvents and heptane. In all instances, the amount of residue exceeds the crystalline content. The crystallinity-insolubility relationship is influenced by molecular weight (as judged by intrinsic viscosity). An increase in crystallinity at constant [η] corresponds to an increase in insolubility; at constant crystallinity, a larger [η] corresponds to greater insolubility. In terms of density, the unextracted polymer may not be regarded as simply a mixture of two well-defined components, since the density of insoluble residue increases with the density of the whole polymer.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1959.070020506
