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Coarsening in molten quiescent polymer blends: The role of the initial morphology
Author(s) -
Willemse R. C.,
Ramaker E. J. J.,
Van Dam J.,
De Boer A. Posthuma
Publication year - 1999
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11566
Subject(s) - materials science , morphology (biology) , polymer , chemical engineering , composite material , polymer science , engineering , genetics , biology
Coarsening of the phase dimensions in polymer blends under quiescent conditions is studied in blends of different morphologies; the dependence of the rate and extent of coarsening on the initial morphology is demonstrated. In blends with a droplet/matrix structure, coarsening via coalescence is found only above the percolation threshold for spherical particles (16 vol%). The rate of coalescence in the droplet/matrix structure is shown to obey the theory of Fortelny and Zivny for coalescence of droplets in quiescent media, and no constant level of the phase dimensions is reached. Below a volume fraction of 0.16 limited coarsening is found only for fibrillar and co‐continuous morphologies. This coarsening is in fact the result of a restructuring because retraction and breakup occur, leading to a droplet/matrix morphology in which the droplet diameter is approximately twice the diameter of the original fiber. Breakup and retraction are completed in a short time relative to coalescence. At higher volume fractions in co‐continuous structures (>30 vol%), these structures do not break up, and coarsening is found to take place by retraction only. No constant level of the phase dimensions is reached in the latter case.