Standard Active Last Updated: Jan 01, 2019
ASTM D7191-18

Standard Test Method for Determination of Moisture in Plastics by Relative Humidity Sensor

Significance and Use

5.1 This test method is intended for use as a control, acceptance, and assessment test.

5.2 Moisture can seriously affect the processability of plastics. It is possible that high moisture content will cause surface imperfections (that is, splay or bubbling) or degradation by hydrolysis. Low moisture (with high temperature) has been known to cause solid phase polymerization.

5.3 The physical properties of some plastics are greatly affected by the moisture content.


1.1 This test method covers the quantitative determination of water down to 20 ppm in plastics using a relative humidity sensor.

1.2 Values stated in SI units are to be regarded as standard.

1.3 Specimens tested in this test method can reach or exceed 250°C, use caution when handling them after testing has completed.

1.4 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.

Note 1: There is no known ISO equivalent to this standard.

1.5 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.

Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Book of Standards Volume: 08.03
Developed by Subcommittee: D20.70
Pages: 4
DOI: 10.1520/D7191-18
ICS Code: 83.080.01