ASTM D731

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 764 psi (5.3 MPa), 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 530 to 5300 psi (3.7 to 36.5 MPa).

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered 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 and health practices and determine the applicability of regulatory limitations prior to use.

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

2. Referenced Documents

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

Index Terms

molding index; plasticity; thermosets; Molding index; Thermosetting materials/properties; Thermosetting plastics; ICS Number Code 83.080.10 (Thermosetting materials)

Citing ASTM Standards

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