Ultracentrifugal equilibrium measurement of high polymer solutions at elevated temperatures
作者:
Akira Kotera,
Naomichi Iso,
Akitaka Senuma,
Takeshi Hamada,
期刊:
Journal of Polymer Science Part A‐2: Polymer Physics
(WILEY Available online 1967)
卷期:
Volume 5,
issue 2
页码: 277-288
ISSN:0449-2978
年代: 1967
DOI:10.1002/pol.1967.160050204
出版商: John Wiley&Sons, Inc.
数据来源: WILEY
摘要:
AbstractTo investigate the solution properties of polyethylene, which has the simplest structure of the vinyl polymers, experiments were made with a magnetically suspended equilibrium ultracentrifuge. Preliminary studies were carried out with a polystyrene–chloroform system at 25°C. and a polystyrene–methylcyclohexane system at 68°C. (which is close to the theta temperature) in order to check the difficulties involved in the flotation equilibrium in the former case and the high temperature measurement in the latter. However, no trouble was encountered in either system, and the results were discussed and compared with earlier results for polystyrene solutions. It was found that chloroform is a good solvent for polystyrene, and the measured weight‐average molecular weight is somewhat smaller than the value obtained in a theta solvent. After overcoming some technical difficulties involved in studies at higher temperatures, we carried out experiments on polyethylene in α‐chloronaphthalene at 130°C. The results are considered reasonable by comparison with results obtained by other methods. The sample employed, Marlex 50 of melt index 0.7, has a wide molecular weight distribution: i.e.,Mz/Mw= 5.2 andM
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