Nonlinear Viscoelastic Behavior of Butadiene—Acrylonitrile Copolymers Filled with Carbon Black

1978 ◽  
Vol 51 (2) ◽  
pp. 322-334 ◽  
Author(s):  
N. Nakajima ◽  
H. H. Bowerman ◽  
E. A. Collins
Keyword(s):  
Carbon Black ◽  
Tensile Stress ◽  
Strain Hardening ◽  
Strain Softening ◽  
Capillary Flow ◽  
Complex Viscosity ◽  
Angular Frequency ◽  
Stress Strain ◽  
Flow Measurements ◽  
Acrylonitrile Copolymers

Abstract Various viscoelastic measurements including dynamic mechanical measurements in tension at 110 Hz from −60–160°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.

Capillary Rheometry of Carbon-Black-Filled Butadiene—Acrylonitrile Copolymers

1975 ◽  
Vol 48 (4) ◽  
pp. 615-622 ◽  
Author(s):  
N. Nakajima ◽  
E. A. Collins
Keyword(s):  
Shear Rate ◽  
Carbon Black ◽  
Tensile Stress ◽  
Capillary Flow ◽  
Complex Viscosity ◽  
Appreciable Effect ◽  
Stress Strain ◽  
Capillary Rheometry ◽  
Strain Behavior ◽  
Acrylonitrile Copolymers

Abstract Capillary rheometry of carbon-black-filled butadiene—acrylonitrile copolymers at 125°C was performed over a wide shear rate range. The data were corrected for pressure loss in the barrel and at the capillary entrance, and for the non-Newtonian velocity profile (Rabinowitsch correction). No appreciable effect of pressure on viscosity was observed. The die swell values were very small, 1.1–1.4. This fact and the shape of the plots of shear stress vs. shear rate imply the presence of a particulate structure, which is probably built by carbon black surrounded with bound rubber. Unlike the behavior of raw amorphous elastomers, the steady-shear viscosity, the dynamic complex viscosity, and the viscosity calculated from tensile stress-strain behavior were significantly different from each other. That is, the capillary flow data indicated an alteration of the structure towards strain softening, and the tensile stress-strain behavior showed strain hardening, indicating retention of the structure up to the yield point. In the dynamic measurement, being conducted at very small strain, the structure is least disturbed. With unfilled elastomers essentially the same deformational mechanism was believed to be responsible in these three measurements, because the results can be expressed by a single master curve.

Viscoelastic Behavior of Butadiene-Acrylonitrile Copolymers at Small and Large Deformations and Their Ultimate Properties

1973 ◽  
Vol 46 (2) ◽  
pp. 417-424 ◽  
Author(s):  
N. Nakajima ◽  
H. H. Bowerman ◽  
E. A. Collins
Keyword(s):  
Shear Rate ◽  
Stress Relaxation ◽  
Tensile Stress ◽  
High Speed ◽  
Capillary Flow ◽  
Viscoelastic Behavior ◽  
Stress Strain ◽  
Flow Measurements ◽  
Acrylonitrile Copolymers ◽  
Good Agreement

Abstract With four samples of butadiene-acrylonitrile copolymers the following viscoelastic measurements have been performed: dynamic mechanical measurements in tension at 110 Hz from −60 to 180° C, tensile stress relaxation measurements with 100 per cent elongation at 25, 54, and 97.5° C, capillary flow measurements at 70, 100, and 125° C, and high-speed tensile stress-strain measurements carried to break at 25, 54, and 97° C. All the data have been treated with the same equation for the time-temperature conversion. The complex viscosity-frequency curves calculated from the dynamic measurements were found to be in good agreement with the capillary viscosity-shear rate curves. From the stress-strain relationship at the yield point the viscosity is estimated; such viscosity as a function of the strain rate is similar to the viscosity-shear rate curve. Good agreement was found with some samples. The elongation to break may be predicted with some samples from the treatment of stress relaxation data together with steady shear flow data.

Comparison of Tensile and Shear Behavior of Carbon-Black-Filled Elastomers

1987 ◽  
Vol 60 (4) ◽  
pp. 761-780 ◽  
Author(s):  
N. Nakajima ◽  
J. J. Scobbo ◽  
E. R. Harrell
Keyword(s):  
Carbon Black ◽  
Tensile Stress ◽  
High Speed ◽  
Complex Viscosity ◽  
Small Strain ◽  
Shear Behavior ◽  
Dynamic Shear ◽  
Stress Strain ◽  
Strain Behavior ◽  
Tensile Tester

Abstract Four NBR's and 2 SBR's with 40 phr carbon black and one SBR with 56 phr carbon black were characterized in both tensile stress-strain behavior and small-strain dynamic-shear behavior. The room temperature tensile stress-strain behavior was determined at strain rates of 0.00690, 0.0187, 0.0975, 0.0162, and 0.253 s−1. For dynamic-shear observations, loss and storage moduli were used to calculate the complex viscosity-frequency curve at small deformations and frequencies of 0.1 to 100 rad/s. Also, these data from tensile and shear experiments were compared with previous data from a capillary rheometer, high-speed tensile tester, and oscillatory tensile tester. Strain-time correspondence was found applicable to large-deformation tensile data up to the yield point. The formation of an anisotropic aggregate density in elongational deformation explains the higher viscosity and modulus for tensile behavior relative to small-strain shear behavior at similar conditions. In shear deformation and flow, the formation of an anisotropic density of aggregates does not seem to occur appreciably.

Mechanism of the Modulus Increase of Carbon-Black-Filled Rubber at Small Extension

2011 ◽  
Vol 284-286 ◽  
pp. 1969-1973
Author(s):  
Xiao Ling Hu ◽  
Yong Ouyang ◽  
Xiong Zhou ◽  
Wen Bo Luo
Keyword(s):  
Carbon Black ◽  
Tensile Stress ◽  
Volume Fraction ◽  
Tensile Modulus ◽  
Homogenization Method ◽  
Stress Strain ◽  
Filled Rubber ◽  
Strain Relationship ◽  
Filled Rubbers ◽  
Relationship Of

The tensile stress-strain relationship of rubbers is fairly linear and can be used for obtaining tensile modulusE. In this work we analyzed the tensile stress-strain relationship of filled rubber experimentally and employed the extended 2D homogenization method to compute the modulus of the carbon black (CB) filled rubbers with various CB volume fractions ranging from 5% to 25%. The results reveal that the modulus of CB-filled rubbers increased with the increase in CB volume fraction and in CB aggregation.

Strain Amplification of Elastomers Filled with Carbon Black in Tensile Deformation

1988 ◽  
Vol 61 (1) ◽  
pp. 137-148 ◽  
Author(s):  
N. Nakajima ◽  
J. J. Scobbo
Keyword(s):  
Carbon Black ◽  
Tensile Stress ◽  
Tensile Deformation ◽  
Molecular Architecture ◽  
Dynamic Shear ◽  
Treatment Procedure ◽  
Stress Strain ◽  
Strain Measurements ◽  
Unique Pattern ◽  
Data Treatment

Abstract This work is based on data previously obtained by the tensile stress-strain and dynamic-shear measurements with several gum rubbers and carbon-black-filled compounds. The gum rubbers were three NBR's of different molecular architecture and two SBR's, one of which was oil extended. The compounds contained 40 phr of N550 carbon black. Through the data treatment procedure developed in this work, the strain amplifications in the dynamic shear and tensile stress-strain measurements were evaluated with the uncrosslinked compounds. Each compound showed a unique pattern of strain amplification.

Effects of Flow Response on the Failure Pressure of Pipelines

2020 ◽  
Author(s):  
Brian N. Leis
Keyword(s):  
Numerical Analysis ◽  
Tensile Stress ◽  
Strain Hardening ◽  
Yield Stress ◽  
Strain Curve ◽  
Ground Movement ◽  
Pipe Steels ◽  
Stress Strain ◽  
Line Pipe ◽  
Flow Response

Abstract The flow properties of line-pipe steels control the failure resistance of the pipe, and as such are key in successful pipeline design, and in understanding the factors controlling failures when they occur. As first-principals predictive models are challenged to quantify the flow response in typical line-pipe steels, engineers must rely on empirically developed properties to support numerical analysis for purposes of design and/or integrity management. Stress-based design logically relies on a limiting stress, whereas strain-based design used to address issues like ground movement relies on a limit strain. Post-yield these limits are coupled through the steel’s stress-strain curve and strain-hardening response. Because the burst-pressure of pipes has been shown to depend on the steel’s collapse stress as well as its strain-hardening exponent, n, engineers will need more that the yield stress, Y, or the tensile stress, T, to adequately characterize a pipeline’s resistance to failure. This paper presents results for the mechanical properties of line-pipe steels developed up to the ultimate tensile stress, or beyond. These stress-strain curves reflect 1) Grades ranging from vintage A25 through recent X100 production. These results have been analyzed to quantify n, Y, and T. These results have further been trended to relate commonly available metrics like Y/T and n, and provide a rational basis for the choice of properties input to numerical analysis. It is apparent from this work that current correlations between n and Y/T diverge from the trend for the lower-strength Grades. Further, these results show that within a Grade the value of n is a strong function of the ratio of the actual yield stress (AYS) normalized by SMYS, with this dependence indicative of differences in the chemistry and processing used to achieve the Grade. The effects of n and its dependence on the ratio AYS/SMYS are illustrated regarding the predicted response of line pipes subject to increasing pressure. These predictions have been validated by comparison with results for about 20 full-scale tests to illustrate the viability of this technology.

Study on Durability of Engineered Cementitious Composites

2011 ◽  
Vol 236-238 ◽  
pp. 2688-2693 ◽  
Author(s):  
Hui Qing Xue ◽  
Zong Cai Deng
Keyword(s):  
Tensile Stress ◽  
Crack Resistance ◽  
Strain Hardening ◽  
Tensile Load ◽  
Strain Curve ◽  
Uniaxial Tensile ◽  
Cementitious Composites ◽  
Stress Strain ◽  
Engineered Cementitious Composites ◽  
Pva Fiber

Engineered cementitious composites (ECC) has good ductility, with its unique strain hardening and multiple cracking characteristics. Through the research of uniaxial direct tension performance and durability tests of ECC blending with polyvinyl alcohol (PVA) fiber, the tensile stress-strain curves, the freeze-thaw resistances and the impermeability of ECC were analyzed. The tensile stress - strain curve results show strain hardening of ECC achieved under the uniaxial tensile load; PVA fiber has good crack resistance toughening effect, can significantly improve crack resistance and deformation capacity of cementitious composites. The maximum tensile strain of the ECC is between 3800με to 8657με (20-50 times that of polypropylene fiber concrete) displays high toughness and large deformation characteristics. The freezing level of the ECC is higher than F300, which is ideal for the maintenance and reinforcement of concrete structures in cold regions. Domestic and imported PVA fiber can significantly improve the impermeability and crack resistance of the ECC.

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