ASTM D6746 - 15(2020)

    Standard Test Method for Determination of Green Strength and Stress Relaxation of Raw Rubber or Unvulcanized Compounds

    Active Standard ASTM D6746 | Developed by Subcommittee: D11.12

    Book of Standards Volume: 09.01

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    Significance and Use

    5.1 The stress-strain properties of unvulcanized rubber (either in a compound or in the raw state) are important to certain processing operations in the rubber industry. These unvulcanized rubber properties are frequently referred to as “green strength.”

    5.2 Green strength is determined primarily by the physical and chemical characteristics of polymers, such as molecular weight, tendency to crystallize, degree of branching, and so forth. It is also related to the compound formulation, particularly filler and plasticizer content, and the presence of peptizers. Green strength can be a good indication of processing behavior. It is a particularly important characteristic for all processing operations in which elongation predominates.

    5.3 Green strength is dependent on the test piece preparation, rate of extension, and test temperature. Therefore, a single-point method cannot be expected to give correlation between green strength and processing behavior over the whole range of processing conditions.

    1. Scope

    1.1 This test method covers methods to evaluate a characteristic of raw rubber or unvulcanized rubber compounds that is designated as green strength. This special strength property for uncured rubbers is an important processing performance attribute in rubber product manufacturing.

    1.2 The values stated in SI units are to be regarded as 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.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D412 Test Methods for Vulcanized Rubber and Thermoplastic ElastomersTension

    D1349 Practice for RubberStandard Conditions for Testing

    D3182 Practice for RubberMaterials, Equipment, and Procedures for Mixing Standard Compounds and Preparing Standard Vulcanized Sheets

    D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries

    ICS Code

    ICS Number Code 83.040.20 (Rubber compounding ingredients)

    UNSPSC Code

    UNSPSC Code 13101500(Natural rubber)

    Referencing This Standard
    Link Here
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    DOI: 10.1520/D6746-15R20

    Citation Format

    ASTM D6746-15(2020), Standard Test Method for Determination of Green Strength and Stress Relaxation of Raw Rubber or Unvulcanized Compounds, ASTM International, West Conshohocken, PA, 2020,

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