ASTM D6814 Standard Test Method for Determination of Percent Devulcanization of Crumb Rubber Based on Crosslink Density

    What is ASTM D6814?

    ASTM D6814 is a standard test method for assessing the percentage of devulcanization in crumb rubber. The devulcanization process weakens the cross-links created during vulcanization, helping restore the processing properties of recycled rubber and enabling its use in new rubber products. During testing, the original vulcanized rubber is tested to determine its crosslink density, and the treated crumb rubber is tested to determine its crosslink density. The measured increase in crosslink density gives a quantitative measure of the devulcanization. ASTM D6814 (Standard Test Method for Determination of Percent Devulcanization of Crumb Rubber Based on Crosslink Density) provides a quantitative measure of percent devulcanization by measuring crosslink density. These results can be used to compare devulcanization techniques, optimize devulcanization conditions, evaluate the quality of devulcanized rubber, and assess the consistency of the devulcanized rubber product.

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    Get Certified ASTM D6814 Testing for Reliable Devulcanization Evaluation

    The ASTM D6814 test method determines percent devulcanization by measuring crosslink density in devulcanized rubber and control crumb rubber. Laboratory testing can help evaluate recycling efficiency, process consistency, material qualifications, and product development. Manufacturers and rubber compounders can use ASTM D6814 results to evaluate the extent of devulcanization in recycled rubber and support subsequent material-development decisions. These results help optimize devulcanization processes and ensure the devulcanized material meets the required properties for subsequent applications.

    What is the Scope of ASTM D6814 Test Standard?

    ASTM D6814 covers determining percent devulcanization from crosslink density measurements of devulcanized rubber and control crumb rubber in the laboratory. This standard-

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    • Calculates the degree of devulcanization of crumb rubber.
    • Compares crosslink density measurements of devulcanized rubber and control crumb rubber.
    • Determines the effectiveness of the rubber devulcanization processes.
    • Supports evaluation of devulcanized rubber during recycling and material development.
    • Provides the data used to compare and optimize processes.

    What are the Uses of ASTM D6814 Testing?

    ASTM D6814 determines the percent devulcanization of crumb rubber through crosslink density measurements. The test provides quantitative data to compare devulcanization technologies and optimize processes. The results also support the development of recycled rubber materials with uniform, predictable properties.

    • Tire recycling companies evaluate the effectiveness of devulcanization processes.
    • Manufacturers of rubber products evaluate reclaimed rubber for reincorporation into new rubber products.
    • Research labs test different devulcanization technologies.
    • Materials developers can use devulcanization data to compare treatment processes and evaluate the suitability of treated crumb rubber for subsequent applications.
    • Quality control laboratories monitor recycled rubber consistency.
    • Product development teams test treated crumb rubber to determine its potential for new applications.

    What Materials Can Be Tested Under ASTM D6814?

    ASTM D6814 is used for crumb rubber from vulcanized rubber products such as recycled tire rubber, reclaimed rubber, vulcanized elastomers, and treated crumb rubber that can be reused in rubber manufacture.

    Why is ASTM D6814 Important for Devulcanization Evaluation?

    ASTM D6814 offers a quantitative method to measure the extent of devulcanization in rubber. Regular testing enables manufacturers to optimize treatment processes, improve the quality of recycled materials, evaluate different technologies, minimize waste, and develop sustainable rubber products.

    ASTM D6814 Equipment and Sample Preparation Guide

    Accurate results require representative control and devulcanized rubber samples and appropriate equipment for determining crosslink density. Laboratories can reduce variations when measuring crosslink density through consistent preparation.

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    Specimen DetailsRepresentative samples include vulcanized crumb rubber, recycled tire rubber, reclaimed rubber, and devulcanized rubber from thermal, chemical, mechanical, or other processing.
    Specimen PreparationASTM D6814 is a comparison of crosslink density measurements of devulcanized rubber and control crumb rubber. Crumb rubber is carefully prepared, and foreign material and contaminants which would interfere with crosslink density measurements are removed.
    Specimen DimensionsASTM D6814 tests crumb rubber instead of standard-size test specimens. The number of samples required for the test is determined, and the quantity of samples prepared.
    InstrumentationEquipment used for crosslink-density measurements includes analytical balances, solvent-extraction or swelling equipment, suitable solvent containers, temperature-controlled equipment, drying equipment, and other measuring equipment required by the applicable crosslink-density procedure.

    Testing Procedures and Requirements for Devulcanization Evaluation

    ASTM D6814 provides a method for determining percent devulcanization from crosslink density measurements of devulcanized rubber and control crumb rubber. Laboratories achieve reliable, repeatable results through consistent specimen preparation, extraction procedures, measurements, and calculations.

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    Specimen PreparationRepresentative crumb rubber samples are taken from the original and devulcanized materials, and technicians clean, condition, and size them as specified. 
    Sample ConditioningThe testing team exposes the rubbers to the required conditions and removes any material that could interfere with the crosslink density determination.
    Crosslink Density MeasurementThe laboratory determines the crosslink density of the control crumb rubber and devulcanized rubber using the applicable measurement procedure.
    Data Collection and Comparative EvaluationTechnicians document the sample identification, material condition, treatment information, crosslink density measurements, and test parameters. The laboratory determines the crosslink density of the control crumb rubber and devulcanized rubber.
    CalculationTechnicians use the measured crosslink density values to calculate the devulcanization percentage by applying the specified calculation method and comparing the crosslink density values of the original and devulcanized rubber.
    Result AnalysisThe calculated percentage provides a quantitative indication of the extent of devulcanization based on the measured crosslink densities.
    Documentation and ReportingLaboratory reports will generally contain the following data: sample identification, rubber type, initial crosslink density, treated crosslink density, percent devulcanization, test conditions, analytical data, observations, etc.

    ASTM D6814 Testing Process and Data Collection

    Technicians prepare control crumb rubber and devulcanized rubber samples for crosslink density measurement. The samples are prepared and conditioned before measuring their crosslink densities. The laboratory records the measured values and compares them to the original vulcanized rubber. Operators then measure the percent devulcanization and interpret the results based on ASTM D6814.

    The image shows laboratory equipment used to evaluate crosslink density in untreated and devulcanized crumb rubber for determining percent devulcanization according to ASTM D6814.
    ASTM D6814 Crosslink Density Testing of Devulcanized Crumb Rubber

    Common Challenges and Troubleshooting

    Inconsistent sample preparation, contamination, incomplete or inconsistent analytical preparation, inaccurate measurements, and calculation errors can affect the calculated percent devulcanization. Laboratories can improve repeatability through careful sample handling, controlled analytical conditions, accurate measurements, and consistent procedures.

    Analysis Results and Interpretation

    • Laboratories calculate percent devulcanization from the applicable crosslink density measurements and report the resulting percentage.
    • Laboratories report crosslink density using the applicable SI units and report percent devulcanization as a percentage.
    • A higher percent devulcanization indicates a greater reduction in crosslink density relative to the control condition.
    • A lower percent devulcanization indicates a smaller reduction in crosslink density under the evaluated treatment conditions.
    • Laboratories should consider the results alongside the treatment conditions and the application of the recycled rubber.

    Link to ASTM D6814

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    Updated on August 19, 2026

    Gokula Srinivasan Selvam
    About Author
    Gokula Srinivasan Selvam
    Gokula Srinivasan Selvam is a Material Testing Associate at Matestlab Inc. and holds a postgraduate degree in Ceramic Engineering from IIT (BHU), Varanasi. His academic background and professional experience are centered on advanced ceramic materials, their processing, characterization, and performance evaluation.
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