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Rheology of molten blends of polyoxymethylene and ethylene‐vinyl acetate copolymer and the microstructure of extrudates as a function of their melt viscosities
Author(s) -
Tsebrenko M. V.,
Rezanova N. M.,
Vinogradov G. V.
Publication year - 1980
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.760201507
Subject(s) - die swell , materials science , polyoxymethylene , extrusion , rheology , copolymer , viscosity , composite material , fiber , ethylene vinyl acetate , microstructure , vinyl acetate , melt spinning , synthetic fiber , polymer
Abstract Blends of polyoxymethylene (POM) with a copolymer of ethylene and vinyl acetate (CEVAc) have been studied. The effect of viscosity ratio for melts of the components on the processes of fiber formation in extrudates and on the rheological properties of the molten blend has been tested. The viscosity ratio of the fiber‐forming POM and the matrix varied in the range 0.35‐27.7. POM ultrathin fibers of unlimited length can be formed in the CEVAc only at a viscosity ratio close to unity. For ratios much greater than unity, the extrudate is found to contain short fibers and a finely dispersed powder or no fibers at all. If the viscosity of the POM melt is lower than that of the matrix, films are formed in addition to fibers. The second factor that governs fiber formation is the extrusion shear stress. An optimum shear stress exists at which the amount of ultrathin fibers is a maximum.