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Nonlinear viscoelastic behavior of butadiene–acrylonitrile copolymers filled with carbon black
Author(s) -
Nakajima N.,
Bowerman H. H.,
Collins E. A.
Publication year - 1977
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1977.070211118
Subject(s) - materials science , viscoelasticity , strain hardening exponent , composite material , strain rate , hardening (computing) , viscosity , ultimate tensile strength , carbon black , elastomer , natural rubber , layer (electronics)
Various viscoelastic measurements including dynamic mechanical measurements in tension at 110 Hz from −60° to 160°C, tensile stress relaxation measurements with 100% elongation at 25°, 54°, and 98°C, capillary flow measurements at 70°, 100°, and 125°C, and high‐speed tensile stress–strain measurements carried to break at 25°, 56°, and 98°C were performed on four samples of carbon black‐filled butadiene–acrylonitrile copolymers. All the data were treated with the same equation for time–temperature conversion. The capillary viscosity–shear rate curves were significantly lower than the complex viscosity–angular frequency curves, indicating “strain softening” with extrusion. The viscosity was estimated from the stress–strain relationship at the yield point. The viscosity as a function of the strain rate is significantly higher than the complex viscosity as a function of angular frequency, indicating “strain hardening” with extension. The strain softening and strain hardening are attributable to the structural changes upon deformation of the carbon black‐filled elastomers. With the unfilled elastomers, neither strain softening nor strain hardening were observed in similar measurements.