【国外标准】 Standard Practice for Use of a Melt Index Strand for Determining Density of Polyethylene

4.1 This practice has been found to be very useful for preparing polyethylene samples suitable for determination of density by Test Method D1505, for quality control purposes, especially in a resin manufacturing facility where fast, reproducible, comparative results are needed. It is not necessarily recommended for resin specifications that are part of a sales contract between the buyer and the seller.4.2 The density of a polyethylene sample is highly dependent on the preparation and thermal history of the specimens. The level of density results obtained by this practice of sample preparation differs from that obtained by other methods as described in Practice D4703, Annex A1.4.3 Before proceeding with this practice, reference shall be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or some combination thereof, covered in the materials specification shall take precedence over those mentioned in this practice. If there are no material specifications, the default conditions apply.1.1 This practice covers the preparation of a sample for polyethylene density determination in accordance with Test Method D1505. The sample consists of a strand produced by extrusion of the polyethylene in accordance with Test Method D1238, Condition 190/2.16 (Melt Index).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, 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.NOTE 2: The precision data on densities measured using this sample preparation practice is listed in Test Method D1505.1.4 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.