Dynamic Viscoelastic Properties of Raw Butadiene—Acrylonitrile Elastomers

1974 ◽  
Vol 47 (4) ◽  
pp. 778-787 ◽  
Author(s):  
N. Nakajima ◽  
E. A. Collins ◽  
P. R. Kumler
Keyword(s):  
Shear Stress ◽  
Tensile Stress ◽  
Viscoelastic Properties ◽  
High Speed ◽  
Master Curve ◽  
Viscoelastic Behavior ◽  
Master Curves ◽  
Stress Strain ◽  
Strain Measurements ◽  
Using Data

Abstract The dynamic viscoelastic properties of four samples of butadiene—acrylonitrile raw elastomers, were obtained with a Rheovibron at 110 Hz and temperature range of −80 to 160°C. The complex properties were in agreement with the master curves obtained previously from stress-strain measurements. A master curve encompassing 13 decades of time was constructed using data from Mooney rheometer shear stress-strain, MTS high speed tensile stress-strain, and the Rheovibron. The master curve represents the rubbery region of viscoelastic behavior in terms of time, temperature, and the magnitude of deformation up to the breaking point. This study demonstrates that corresponding states can be found between small (ca. 1 per cent) and large deformation up to break (e.g., 1400 per cent).

A Master Curve for Amorphous Elastomers Derived from Small and Large Deformations Using Various Instruments

1975 ◽  
Vol 48 (1) ◽  
pp. 69-78 ◽  
Author(s):  
N. Nakajima ◽  
E. A. Collins
Keyword(s):  
Steady State ◽  
Viscoelastic Properties ◽  
High Speed ◽  
Master Curve ◽  
Large Deformations ◽  
Stress Strain ◽  
Strain Measurements ◽  
Mechanical Measurements ◽  
Single Master Curve ◽  
Butadiene Styrene

Abstract Dynamic mechanical measurements, stress—strain measurements, and steady-shear measurements made over a range of temperatures and frequencies or deformation rates are used to characterize the viscoelastic properties of raw elastomers. The measurements involve both small and large deformations. It is shown that the results on either butadiene—acrylonitrile (NBR) or butadiene—styrene (SBR) can be reduced to a single master curve. The instruments and ranges covered included Instron stress—strain (0.2–20 in./min; 25–75°C), Instron capillary (100−104sec −1; 100°C), Rheovibron (110 Hz; 23–156°C), Rheometrics (4×10−2−2.6×102 sec−1; 100°C), MTS high speed tester (267-26 700%/sec; 25–97°C), steady-state Mooney (0.05–20 rpm; 25–150°C) and transient Mooney (0.05 rpm; 25–150°C).

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.

Master Curve for Tensile Stress—Strain Behavior of Amorphous Elastomers at Small and Large Deformations

1974 ◽  
Vol 47 (2) ◽  
pp. 318-332 ◽  
Author(s):  
N. Nakajima ◽  
E. A. Collins ◽  
H. H. Bowerman
Keyword(s):  
Tensile Stress ◽  
Master Curve ◽  
Large Deformations ◽  
Strain Rates ◽  
Stress Strain ◽  
Strain Behavior

Abstract A master curve scheme for small and large deformations was developed for tensile stress-strain behavior of butadiene—acrylonitrile uncrosslinked elastomers. Measurements were carried out at strain rates of 267 to 26,700 per cent/sec at temperatures of 25 to 97° C.

Tensile Stress—Strain Measurements for Characterization of Gum Elastomers and Filled Compounds

1990 ◽  
Vol 63 (4) ◽  
pp. 624-636 ◽  
Author(s):  
N. Nakajima ◽  
M. H. Chu ◽  
R. Babrowicz
Keyword(s):  
Shear Modulus ◽  
Tensile Stress ◽  
Shear Deformation ◽  
Tensile Modulus ◽  
Nonlinear Behavior ◽  
Material Behavior ◽  
Structural Constraints ◽  
Stress Strain ◽  
Strain Measurements ◽  
Diene Rubbers

Abstract For a gum elastomer in its amorphous, isotropic state, shear modulus and tensile modulus are related with a factor of three. This relation is maintained in the range of temperature and time scale defining the rubbery region of the material behavior. When a large deformation is imposed, for example, in tensile stress—strain measurements, the above relation may still be preserved, if the nonlinear behavior can be linearized. The strain—time correspondence principle is the linearization scheme of this work. When a gum elastomer contains various structural constraints, the factor three relation does not apply, even after the application of the above linearization scheme. Example of constraints are excessive amounts of long branches, gel, molecular associations, and reinforcing fillers. These constraints usually make the factor larger than three. This is because the constraints make the large, elongational deformation more difficult to achieve compared to shear deformation. An example of gum elastomer in this work is a polyethylacrylate containing a significant amount of gel. With this polymer, both the presence of gel and the molecular association act as the constraints. However, when 50 phr of carbon blacks are added, the fillers do not act as strong constraints as they do when they are in the diene rubbers. This is because the polyethylacrylate is known to have a weaker affinity to carbon black compared to the diene rubbers. Triblock copolymers, styrene—isoprene—styrene, were examined according to the above treatment; 25% polystyrene copolymer exhibited crosslink-like behavior by the polystyrene domains. However, 14% polystyrene copolymers acted as if they are no crosslinks. When these copolymers are diluted to 44% with an addition of 56% tackifier, the ratio of tensile to shear modulus became less than three. The styrene domains must have effective crosslinks at the small shear deformation, but at large tensile deformations such crosslinks must not be present.

Abrasion Resistance and High Speed Tensile Strength of Elastomers

1966 ◽  
Vol 39 (4) ◽  
pp. 823-840 ◽  
Author(s):  
Ruprecht Ecker
Keyword(s):  
Tensile Strength ◽  
Viscoelastic Properties ◽  
High Speed ◽  
Loss Modulus ◽  
Empirical Relation ◽  
Viscoelastic Behavior ◽  
Experimental Tests ◽  
Test Results ◽  
Resonant Vibrations ◽  
Mechanical Rupture

Abstract In earlier communications, we defined abrasion, especially of tires, as a thermal-oxidative process caused at high velocity of mechanical rupture. Other authors (e.g., Schallamach, Boggs, Zapp etc.), with theoretical and experimental tests, prove the importance of viscoelastic behavior as a characteristic property for abrasion. The results of experiments on six elastomers (NR, IR, BR, SBR, IIR, and EPT) compared in tire tread compounds are communicated and discussed in the present work. Tensile strength was determined over a temperature range of 20° to 140° C at deformation speeds of 10 to 20,000 % elongation per second. Forced, non-resonant vibrations were used to determine viscoelastic properties, e.g., resilience, storage modulus, and loss modulus. As abrasion is a consequence of frictional processes, coefficients of friction, dependent on temperature, were measured on dry, wet, and frosty asphalt/fine concrete track. The apparatus is briefly described. From these test results, an empirical relation established between abrasion, friction, viscoelastic properties, tensile strength at high speed and temperature allows one to predetermine the abrasion behavior of a vulcanizate in the laboratory.

Viscoelastic Behavior of Polyisobutylene under Constant Rates of Elongation

1956 ◽  
Vol 29 (4) ◽  
pp. 1199-1208
Author(s):  
Thor L. Smith
Keyword(s):  
Time Scale ◽  
Viscoelastic Properties ◽  
Viscoelastic Behavior ◽  
Polymeric Materials ◽  
Constant Load ◽  
Distribution Functions ◽  
Large Strains ◽  
National Bureau ◽  
Stress Strain ◽  
Nonlinear Viscoelastic

Abstract A variety of methods has been used to study the viscoelastic properties of polymeric materials. These methods include the response to sinusoidal stress (dynamic measurements), stress relaxation, and creep under constant load and constant stress. The present investigation was made to determine whether or not the viscoelastic properties of rubberlike materials over an extended time scale could be obtained from stress-strain curves measured at different strain rates and temperatures. Polyisobutylene of high molecular weight was selected for study, since its viscoelastic properties have been investigated extensively in a cooperative program sponsored by the National Bureau of Standards. From the data obtained, Marvin has derived the distribution functions of relaxation and of retardation times over a time scale of 10−10 to 107 sec. These functions show quantitatively a change in properties from liquidlike to rubberlike to glasslike with decreasing time scale. The equilibrium stress-strain curves for lightly crosslinked rubber and other elastomers are closely linear for elongations up to 100 per cent. The non-equilibrium (viscoelastic) stress-strain curves for similar and noncrosslinked elastomers might be expected to be linear viscoelastic, as a first approximation, at temperatures above the glass transition, provided the strain and the strain rate are not excessively large. Nonlinear viscoelastic effects are usually pronounced for materials in their glasslike state and at large strains.

Plastic Stress-Strain Relations

1948 ◽  
Vol 159 (1) ◽  
pp. 95-114 ◽  
Author(s):  
W. M. Shepherd
Keyword(s):  
Shear Stress ◽  
Tensile Stress ◽  
Shear Strain ◽  
Maximum Shear Stress ◽  
The Other ◽  
Plastic Strains ◽  
Stress Strain ◽  
Thin Tube ◽  
Shear Strains ◽  
Comparable Magnitude

The author derives stress-strain relations which are applicable to problems in which the elastic and plastic strains are of comparable magnitude. Two alternative criteria are used, one based on the Mises-Hencky function and the other on the maximum shear stress. Shear stress-shear strain curves are deduced from tensile stress-strain curves and the result is in one case compared with experiment. The problem of a thin tube strained in tension beyond the onset of plasticity and then subjected to an increasing torque is considered, and the tensile and shear strains due to the torque are found. A result relating to the energy lost in plastic straining is obtained.

Viscoelastic Behavior Simulation of Cortical Bone Tissues Using Burgers Rheological Model

2015 ◽  
Vol 801 ◽  
pp. 267-272 ◽  
Author(s):  
Alexandru Perescu ◽  
Oana Suciu ◽  
Adela Neamțu ◽  
Cristian Sorin Nes ◽  
Liviu Bereteu
Keyword(s):  
Tensile Stress ◽  
Cortical Bone ◽  
Viscoelastic Properties ◽  
Rheological Model ◽  
Viscoelastic Behavior ◽  
Time Dependent ◽  
Shearing Stress ◽  
Rheological Models ◽  
Behavior Simulation ◽  
Dependent Behavior

The elastic properties of cortical bone tissue and other types of bone have been determined by the classical methods such as tensile stress and shearing stress. In recent years, by nanoindentation method, it has developed techniques for measuring the viscoelastic properties of bone tissues. In the same time, they show effects the dependent on time due to loading. The time dependent behavior of such viscoelastic materials may be described by constitutive equations whose variables are stress, deformation and time. These equations may be expressed by means of rheological models. Furthermore, bone tissues present both the phenomenon of creep and relaxation, indicating that they have a rheological behavior. In this paper viscoelastic behavior of bone is simulated numerically, and analyzed in Simulink, using Burgers rheological model.

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.

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