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Rheological behavior of highly filled ethylene propylene diene rubber compounds
Author(s) -
Markovic M. G.,
Choudhury N. R.,
Dimopoulos M.,
Matisons J. G.,
Dutta N. K.,
Bhattacharya A. K.
Publication year - 2000
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.11234
Subject(s) - die swell , materials science , ethylene propylene rubber , composite material , shear rate , extrusion , shear thinning , natural rubber , rheology , epdm rubber , viscosity , swell , shear stress , thermodynamics , polymer , copolymer , physics
The rheological behavior of highly filled ethylene propylene diene rubber (EPDM) compounds was studied with respect to the effect of curative system, grafted rubber, shear rate, temperature and die swell using a Monsanto Processability Tester (MPT) to gain an understanding of the molecular parameters that control the surface finish. All systems show pseudoplastic behavior. At a particular shear rate, shear viscosity increases with blend ratio. The dependence of flow behavior on extrusion velocity indicates a surface effect. The extrudate die swell and maximum recoverable deformation are related by a linear relationship, which is independent of sulfur/accelerator ratio, extrusion temperature and shear rates and blend ratio. The principal normal stress difference increases nonlinearly with shear stress. Activation energy decreases with shear rate in most cases. The faster relaxing system produces extrudate of better surface quality.