ASTM D731 - 10

    Standard Test Method for Molding Index of Thermosetting Molding Powder

    Active Standard ASTM D731 | Developed by Subcommittee: D20.30

    Book of Standards Volume: 08.01


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    ASTM D731

    Significance and Use

    This test method provides a guide for evaluating the moldability of thermosetting molding powders. This test method does not necessarily denote that the molding behavior of different materials will be alike and trials may be necessary to establish the appropriate molding index for each material in question.

    The sensitivity of this test diminishes when the molding pressure is decreased below 5.3 MPa (764 psi), so pressures lower than this are not ordinarily recommended. This is due to the friction of moving parts and the insensitivity of the pressure switch actuating the timer at these low pressures.

    1. Scope

    1.1 This test method covers the measurement of the molding index (plasticity) of thermosetting plastics ranging in flow from soft to stiff by selection of appropriate molding pressures within the range from 3.7 to 36.5 MPa (530 to 5300 psi).

    1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

    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 and health practices and determine the applicability of regulatory limitations prior to use.

    Note 1—There is no known ISO equivalent to this test method.


    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

    D256 Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics

    D883 Terminology Relating to Plastics

    D957 Practice for Determining Surface Temperature of Molds for Plastics

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method


    ICS Code

    ICS Number Code 83.080.10 (Thermosetting materials)

    UNSPSC Code

    UNSPSC Code


    DOI: 10.1520/D0731-10

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