ASTM D8491-22

Standard Test Method for Recovered Carbon Black—Rheological Non-Linearity of a Rubber Compound by Fourier Transform Rheology

SIGNIFICANCE AND USE
3.1 This test method provides a measure of rheological non-linearity for filled rubber compounds under oscillatory shear conditions: the normalized 3rd harmonic of the torque I3/1.  
3.2 Rheological linearity means that the modulus is a function of frequency only. The shear modulus dependency on both frequency and amplitude of a dynamic deformation is a non-linear, rheological effect. Filled rubbers show a strain dependency of the modulus known as Payne effect. A test method for evaluating the Payne effect can be found in Test Method D8059.  
3.3 One of the main contributions to the Payne effect is the so-called polymer-filler interaction in the range of mid amplitude oscillation shear, MAOS. The MAOS amplitude range is defined as the range where I3/1 is already measurable and increases according to a scaling law, for example, I3/1 ~ γ2. It has been shown that FT rheological measurements are very sensitive to changes in this interaction, and that it is possible to quantify the influence of the filler type and content on the nonlinearity. Interactions between the polymer and particle surface and between the filler particles create a network structure in the compound that not only increases the elasticity of the system but also introduces nonlinear contributions to the stress response.3
SCOPE
1.1 This test method provides a measure of rheological non-linearity of a rubber compound filled with rCB to assess its reinforcement capabilities. This test method requires the use of a sealed cavity rotorless oscillating shear rheometer for the measurement of the torque with increasing sinusoidal strain applied to an uncured rubber compound containing significant amounts of colloidal fillers, such as recovered carbon black, alone or as blend with virgin carbon black.  
1.2 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Historical
• Publication Date: 30-Nov-2022
• ICS: 83.060 - Rubber
• Technical Committee: D36 - Recovered Carbon Black (rCB)
• Drafting Committee: D36.70 - rCB Testing in Rubber

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D8491 − 22
Standard Test Method for
Recovered Carbon Black—Rheological Non-Linearity of a
1
Rubber Compound by Fourier Transform Rheology
This standard is issued under the fixed designation D8491; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3896 Practice for Rubber From Synthetic Sources—
Sampling
1.1 This test method provides a measure of rheological
D6204 Test Method for Rubber—Measurement of Unvulca-
non-linearity of a rubber compound filled with rCB to assess its
nized Rheological Properties Using Rotorless Shear Rhe-
reinforcement capabilities. This test method requires the use of
ometers
a sealed cavity rotorless oscillating shear rheometer for the
D8059 Test Method for Rubber Compounds—Measurement
measurement of the torque with increasing sinusoidal strain
of Unvulcanized Dynamic Strain Softening (Payne Effect)
applied to an uncured rubber compound containing significant
Using Sealed Cavity Rotorless Shear Rheometers
amounts of colloidal fillers, such as recovered carbon black,
alone or as blend with virgin carbon black.
3. Significance and Use
1.2 Units—The values stated in SI units are to be regarded
3.1 This test method provides a measure of rheological
as the standard. No other units of measurement are included in
non-linearity for filled rubber compounds under oscillatory
this standard.
shear conditions: the normalized 3rd harmonic of the torque
I .
1.3 This standard does not purport to address all of the
3/1
safety concerns, if any, associated with its use. It is the
3.2 Rheological linearity means that the modulus is a
responsibility of the user of this standard to establish appro-
function of frequency only. The shear modulus dependency on
priate safety, health, and environmental practices and deter-
both frequency and amplitude of a dynamic deformation is a
mine the applicability of regulatory limitations prior to use.
non-linear, rheological effect. Filled rubbers show a strain
1.4 This international standard was developed in accor-
dependency of the modulus known as Payne effect. A test
dance with internationally recognized principles on standard-
method for evaluating the Payne effect can be found in Test
ization established in the Decision on Principles for the
Method D8059.
Development of International Standards, Guides and Recom-
3.3 One of the main contributions to the Payne effect is the
mendations issued by the World Trade Organization Technical
so-called polymer-filler interaction in the range of mid ampli-
Barriers to Trade (TBT) Committee.
tude oscillation shear, MAOS. The MAOS amplitude range is
defined as the range where I is already measurable and
3/1
2. Referenced Documents
2
increases according to a scaling law, for example, I ~ γ . It
3/1
2
2.1 ASTM Standards:
has been shown that FT rheological measurements are very
D1485 Practice for Rubber from Natural Sources—
sensitive to changes in this interaction, and that it is possible to
Sampling and Sample Preparation
quantify the influence of the filler type and content on the
D3191 Test Methods for Carbon Black in SBR (Styrene-
nonlinearity. Interactions between the polymer and particle
Butadiene Rubber)—Recipe and Evaluation Procedures
surface and between the filler particles create a network
D3192 Test Methods for Carbon Black Evaluation in NR
structure in the compound that not only increases the elasticity
(Natural Rubber)
of the system but also introduces nonlinear contributions to the
3
stress response.
4. Apparatus
1
This test method is under the jurisdiction of ASTM Committee D36 on
4.1 Torsion Strain Rotorless Oscillating Rheometer with a
Recovered Carbon Black (rCB) and is the direct responsibility of Subcommittee
D36.70 on rCB Testing in Rubber.
Sealed Cavity in accordance with Test Method D6204, oper-
Current edition approved Dec. 1, 2022. Published December 2022. DOI:
ated in the test mode called strain sweep, in which the strain
10.1520/D8491-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Schwab, L. et al., “Fourier-Transform Rheology of Unvulcanized, Carbon
Standards volume information, refer to the standard’s Document Summary page on Black Filled Styrene Butadiene Rubber,” Macromol. Mater. Eng., 2016, 301, pp.
the ASTM website. 457−468.
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D8491 − 22
amplitude is programmed to change in steps under co
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