Rubber Test Types

TA Instruments’ Rubber Testing Instruments perform a wide array of tests for the measurement of rheological and physical properties of polymers, rubber, and rubber compounds and all stages of manufacture. Tests of every level of complexity, from routine manufacturing control, to upstream research and development are performed with equal degrees of ease and precision.

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International Standards
Testing standard descriptions and compatible instruments conforming to the specifications of many standards organizations such as ASTM, DIN, and ISO and many test types, such as vulcanization, hardness, density, and Mooney Viscosity.

STANDARDS DESCRIPTION
ASTM D5289 Standard Test Method for Rubber Property—Vulcanization Using Rotorless Cure Meters

RPA elite, RPA flex, MDR one

ASTM D6048 Standard Practice for Stress Relaxation Testing of Raw Rubber, Unvulcanized Rubber Compounds, and Thermoplastic Elastomers

RPA elite, RPA flex

ASTM D6204 Standard Test Method for Rubber—Measurement of Unvulcanized Rheological Properties Using Rotorless Shear Rheometers

RPA elite, RPA flex

ASTM D6601 Standard Test Method for Rubber Properties—Measurement of Cure and After Cure Dynamic Properties Using a Rotorless Shear Rheometer

RPA eliteRPA flex

ASTM D7050 Standard Practice for Rubber from Natural Sources Sampling and Sorting Bales Based on Predicted Processing Properties

RPA eliteRPA flex

ASTM D8059 ASTM 8059 Standard Test Method for Rubber Compounds-Measurement of Unvulcanized Dynamic Strain Softening (Payne Effect) Using Sealed Cavity Rotorless Shear Rheometers

RPA eliteRPA flex

ISO 6502 Guide to the use of curemeters
RPA eliteRPA flexMDR one
ISO 13145 Determination of viscosity and stress relaxation using a rotorless sealed shear rheometer
RPA elite, RPA flex
DIN 53529 Testing of rubber and elastomers; measurement of vulcanization characteristics (curometry); evaluation of cross-linking isotherms in terms of reaction kinetics
RPA eliteRPA flexMDR one
ISO 2781 Rubber, vulcanized or thermoplastic – Determination of density
ADT
ASTM D1817 Standard Test Method for Rubber Chemicals—Density

ADT

ISO 868 Plastics and ebonite — Determination of indentation hardness by means of a durometer (Shore hardness)

AHT

NF T51-174 Plastics and ebonite – Determination of indentation hardness by means of a durometer shore hardness. AHT
ASTM D2240 Standard Test Method for Rubber Property—Durometer Hardness

AHT

DIN 53505 Shore A and Shore D Hardness Testing of Rubber (Shore A). AHT
ISO 7619 Rubber, vulcanized or thermoplastic — Determination of indentation hardness

AHT

NF T46-052 Rubber, vulcanized or thermoplastic – Determination of indentation hardness – Part 1: durometer method (Shore hardness). AHT
ASTM D1646 Standard Test Methods for Rubber—Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)

MV one

ISO 289 Rubber, unvulcanized — Determinations using a shearing-disc viscometer

MV one

DIN 53523 Testing of Rubber and Elastomers; Testing with the Mooney Shearing Disk Viscometer; Determining the Scorching Behaviour MV one
BS 903-A58 Physical testing of rubber – Part A58: Methods using the Mooney viscometer. MV one

Mooney Viscometer Experiments 

Descriptions and examples of basic and advanced Mooney Viscometer experiments. Mooney Viscometer experiments are easy to perform, provide continuous comparison with historical data, and reveal information about rubber viscosity and elasticity. Mooney Viscometer experiments are easy to perform, provide continuous comparison with historical data, and reveal information about rubber viscosity and elasticity. Typical tests include Mooney Viscosity, Stress Relaxation, and Scorch. More advanced experiments at multiple rates provide additional insight into polymer shear rate dependence.

  • Mooney Viscosity
  • Mooney Stress Relaxation
  • Mooney Scorch
  • Mooney Viscosity at Multiple Rates

Mooney Viscosity

The Mooney Viscosity test is a well-established method for characterizing uncured rubber materials. Following well- defined standard procedures, the sample is preheated for a defined period, then sheared at a constant rate.The Mooney Viscosity is recorded from the end of this deformation stage. in the present example, the outstanding precision of the MVone Mooney Viscometer is demonstrated. Three polymer samples were tested in duplicate.The outstanding run-to-run reproducibility and the ease of distinguishing one polymer from another is clear.

Suitable Instrument: MV one

Mooney Stress Relaxation

While the Mooney Viscosity experiment is typically indicative of polymer viscosity, stress relaxation can be used to identify elasticity. Upon completion of the Mooney Viscosity measurement, the rotor is stopped immediately and the torque decay is observed.The slope of this decay is indicative of polymer elasticity, which may be related to a branched architecture and correlates well with extrudate swell in rubber processing.

Suitable Instrument: MV one

 

Mooney Scorch

mooney-scorchThe Mooney Viscometer can also be used to measure the initial rate of vulcanization. In this example, a styrene butadiene rubber (SBR) was tested for prevulcanization characteristics at 150°C using the small rotor. For this simple experiment the initial Mooney viscosity, minimum viscosity, scorch times, and cure index are the most commonly reported values.

Suitable Instrument: MV one

 

Mooney Viscosity at Multiple Rates

In addition to the viscosity at a single rate and temperature, the MV one Mooney Viscometer can measure viscosity at a range of shear rates and temperatures. This range of rates allows a more complete understanding of the polymer behavior, especially a tendency for shear thinning. Low rates in Mooney Viscosity experiments can also be beneficial for measuring highly elastic materials that are otherwise inaccessible to Mooney Viscosity measurements.

Suitable Instrument: MV one

RPA and MDR Experiments 
Oscillation and transient tests of curing and viscoelasticity. These tests are the most common for rubber rheology and provide information about vulcanization and curing, viscoelastic properties, filler structure, polymer architecture, and more.

The RPA and MDR instruments perform oscillation, or dynamic measurements of polymer and rubber properties. These tests provide basic torque information, as well as viscoelastic properties such as the storage and loss modulus, tan δ, and viscosity. Oscillation tests are popular for studies of curing, or vulcanization, as well as measurements of viscoelastic properties, filler structure, polymer architecture, and more for both green and cured rubber.

  • Isothermal Cure
  • Non-isothermal Cure
  • Isothermal Curing at Variable Strain
  • Isothermal Frequency Sweep
  • Strain Sweep for Filler Loading
  • High Strain Non-Linear Behavior
  • Time Dependent Structure Breakdown
  • Cure with Blowing Reaction

Isothermal Cure

Isothermal cure experiments are critical for rubber and elastomer processing. The TA Instruments rubber rheometers provide high precision data that is simple to analyze. All the important characteristics, such as minimum and maximum viscosity, scorch time, and conversion time can be calculated easily and automatically. The data can also be handled in its complete graphical form for comparison or alternative analyses.

Suitable Instruments: MDR one, RPA flex, RPA elite

Non-isothermal Cure

In addition to the industry-standard isothermal cure methods, the RPA and MDR can perform non-isothermal cure experiments. These experiments can be programmed to follow virtually any temperature profile and are especially valuable when simulating manufacturing processes that are not isothermal. Non-isothermal curing experiments may also be coupled with isothermal tests such as strain and frequency sweeps before or after cure to provide a more complete material data set before, through, and after cure.

Suitable Instruments: MDR oneRPA flexRPA elite

 

Isothermal Curing at Variable Strain

While standard test methods often call for a single strain and frequency value to be used for all materials (0.5°, 1.67 Hz), these are not always the ideal conditions for every material. In the present example, the sample material is tested by isothermal cure at three deformation amplitudes, five times each. At the standard of 0.5° and 0.4° the experimental variability is extremely broad. This is because these experiments are performed at strains beyond the linear viscoelastic limit for this material. Testing at a smaller amplitude (0.3°) produces valid data with greatly improved reproducibility.

Suitable Instruments: RPA flex, MDR oneRPA elite

Isothermal Frequency Sweep

Measuring the frequency-dependent viscoelastic properties of a material is a powerful way to understand its molecular structure. A frequency sweep as shown can reveal information about the average molecular weight (crossover frequency) and molecular weight distribution (crossover modulus).

Suitable Instruments: RPA flexRPA elite

 

Strain Sweep for Filler Loading

The strain-dependent modulus is particularly important as an indicator of the amount and type of rubber filler dispersion and interaction. in the present example, the impact of carbon black addition at five different levels is seen in the low strain region. High strain behavior is generally insensitive to filler addition, as it is less sensitive to filler-filler interaction and more dependent on polymer molecular weight, and polymer-filler interactions.

Suitable Instruments: RPA flexRPA elite

High Strain Non-Linear Behavior

The viscoelastic response of a material at very high strains differs not only in magnitude from its linear counterpart, but also in type. The careful examination of a polymer’s stress- strain response at high strains reveals features associated with filler content and structure, as well as polymer architecture. in the present example, qualitatively different features are observed at large strains for a linear polymer, branched polymer, and a blend of the two. Both the uncorrelated data, and the FT analysis of periodic data are available through the scarabaeus software to allow in-depth analysis of this new type of data.

Suitable Instruments: RPA flexRPA elite

Time Dependent Structure Breakdown

The van der Waals interactions that lead to increased modulus in carbon black filled rubber are highly sensitive to processing. in this example, identical samples are subjected to different lengths of milling after being removed from the mixer. Carbon network structure is reduced with each increase in milling time up to 8 minutes, after which the modulus was unchanged with increased milling.This provides critical information about the amount of milling needed to create a consistent workable material.

Suitable Instruments: RPA flexRPA elite

Cure with Blowing Reaction

Final product density and mechanical performance are often enhanced through the use of blowing agents to create a cellular architecture. These blowing agents generate gas during decomposition in parallel with the curing reaction. Monitoring sample pressure through the curing reaction is an effective way to quantify the blowing reaction, allowing for the characterization of curing and blowing in a single experiment.These two processes must be balanced in order to form the desired cell architecture in the finished product.

Suitable Instruments: MDR oneRPA flexRPA elite