ASTM D1921-18

4.1 These test methods are used to determine particle size distribution and therefore are useful for determining lot-to-lot uniformity.

4.2 The particle sizes of plastic materials affect the handling characteristics and sometimes will affect the processing characteristics of some polymers.

1.1 These test methods cover the measurement of the particle size of plastic materials in the powdered, granular, or pelleted forms in which they are commonly supplied. As these test methods utilize dry sieving, the lower limit of measurement is considered to be about 38 μm (No. 400 sieve). For smaller particle sizes, sedimentation test methods are recommended.

1.2 Two test methods are described:

1.3 The values stated in SI units are to be regarded as standard for dimensions of the wire cloth openings and the diameter of the wires used in the wire cloth.

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.

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.