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:
Continued shearing of molten long-chain branched acetal polymers raises their melt flow rates manyfold. The increase is not due to molecular degradation, as evidenced by constancy of inherent viscosity, and by the ability to reverse the increase by dissolving and reprecipitating the polymer. Shearing was found to have only a relatively small effect upon the melt viscosity but a very large effect upon the entrance correction for capillary flow. It is suggested that crystallization of branched polymers from solution creates an exceptionally strong entanglement network, and that the observed rheological changes reflect the disruption by shear of this network.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1969.070130122
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