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. Designation: D570 - 22 INTERNATIONAL Standard Test Method for Water Absorption of Plastics1 This standard is issued under the fixed designation D570; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the U.S. Department of Defense. 1. Scope* 3.Terminology 1.1 This test method covers the determination of the relative 3.1 For definitions of terms that appear in this practice rate of absorption of water by plastics when immersed. This relating to plastics, refer to Terminology D883. test method is intended to apply to the testing of all types of 3.2 For definitions of terms that appear in this practice plastics, including cast, hot-molded, and cold-molded resinous relating to quality and statistics (such as precision and bias), products, and both homogeneous and laminated plastics in rod refer to Terminology E456. and tube form and in sheets 0.13 mm (0.005 in.) or greater in thickness. 4. Significance and Use 1.2 The values given in SI units are to be regarded as 4.1 This test method for rate of water absorption has two standard. The values stated in parentheses are for information chief functions: first, as a guide to the proportion of water only. absorbedbyamaterialandconsequently,inthosecaseswhere NoTe 1This test method and ISO 62 are technically equivalent when the test specimen described in 6.2 is used. therelationshipsbetweenmoistureandelectricalormechanical properties, dimensions, or appearance have been determined, 1.3 This standard does not purport to address all of the as a guide to the effects of exposure to water or humid safety concerns, if any, associated with its use. It is the conditions on such properties; and second, as a control test on responsibility of the user of this standard to establish appro- the uniformity of a product. This second function is particu- priate safety, health, and environmental practices and deter- larly applicable to sheet, rod, and tube arms when the test is mine the applicability of regulatory limitations prior to use. made on the finished product. 1.4 This international standard was developed in accor- 4.2 Comparison of water absorption values of various plas- dance with internationally recognized principles on standard- izationestablishedintheDecisiononPrinciplesforthe tics made on the basis of values obtained in accordance with Development of International Standards, Guides and Recom- 8.1 and 8.4 have been found useful. mendations issued by the World Trade Organization Technical 4.3 Ideal diffusion of liquids4 into polymers is a function of Barriers to Trade (TBT) Committee. the square root of immersion time. Time to saturation is strongly dependent on specimen thickness. For example, Table 2. Referenced Documents 1 shows the time to approximate time saturation for various 2.1 ASTM Standards:2 thickness of nylon-6. D883 Terminology Relating to Plastics 4.4 The moisture content of a plastic is very intimately E456 Terminology Relating to Quality and Statistics related to such properties as electrical insulation resistance, 2.2 IsO Standard: dielectric losses, mechanical strength, appearance, and dimen- ISO 62 Plastics-—Determination of Water Absorption3 sions. The effect upon these properties of change in moisture content due to water absorption depends largely on the type of exposure (by immersion in water or by exposure to high This test method is under the jurisdic