ASTM D2839-2005 Standard Practice for Use of a Melt Index Strand for Determining Density of Polyethylene《利用熔体指数纤维测定聚乙烯密度的标准实施规程》.pdf
《ASTM D2839-2005 Standard Practice for Use of a Melt Index Strand for Determining Density of Polyethylene《利用熔体指数纤维测定聚乙烯密度的标准实施规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM D2839-2005 Standard Practice for Use of a Melt Index Strand for Determining Density of Polyethylene《利用熔体指数纤维测定聚乙烯密度的标准实施规程》.pdf(3页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 2839 05Standard Practice forUse of a Melt Index Strand for Determining Density ofPolyethylene1This standard is issued under the fixed designation D 2839; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers the preparation of a sample forpolyethylene density determination in accordance with TestMethod D
3、 1505. The sample consists of a strand produced byextrusion of the polyethylene in accordance with Test MethodD 1238, Condition 190/2.16 (Melt Index).1.2 The values stated in SI units are to be regarded as thestandard. The values given in brackets are for information only.1.3 This standard does not
4、purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no similar or equivalent IS
5、O standard.2. Referenced Documents2.1 ASTM Standards:2D 1238 Test Method for Flow Rates of Thermoplastics byExtrusion PlastometerD 1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD 4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens, Plaques, or
6、 SheetsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 melt index strandthe extrudate produced when poly-ethylene is extruded in accordance with Test Method D 1238,Condition 190/2.16.4. Significance and Use4.1 This
7、practice has been found to be very useful forpreparing polyethylene samples suitable for determination ofdensity by Test Method D 1505, for quality control purposes,especially in a resin manufacturing facility where fast, repro-ducible, comparative results are needed. It is not necessarilyrecommende
8、d for resin specifications which may be a part of asales contract between the buyer and the seller.4.2 The density of a polyethylene sample is highly depen-dent on the preparation and thermal history of the specimens.The level of density results obtained by this practice of samplepreparation differs
9、 from that obtained by other methods asdescribed in Practice D 4703.4.3 Before proceeding with this practice, reference shouldbe made to the specification of the material being tested. Anytest specimen preparation, conditioning, dimensions, or testingparameters, or some combination thereof, covered
10、in thematerials specification shall take precedence over those men-tioned in this practice. If there are no material specifications,the default conditions apply.5. Apparatus5.1 Extrusion Plastometer, as described in Test MethodD 1238.5.2 Hot Plate, to boil water.5.3 Beakers, 250-mL low form, graduat
11、ed, with watch-glasscovers.6. Sample6.1 Polyethylene, in any form suitable for test in accordancewith Test Method D 1238.7. Procedure7.1 Prepare a Melt Index Strand by extruding the sample inaccordance with Test Method D 1238, Condition 190/2.16,dropping the strand on a cool metal plate after cuttin
12、g off.When Procedure B of Test Method D 1238 is used, cut off theextrudate at about the time the timer is actuated and discard.Save the portion extruded during the timed interval.NOTE 2The conditioning procedure as described in 7.2 and 7.3 maybe omitted, if desired; in such case, after a 10-min cool
13、ing period, cut off1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials(D20.15.01).Current edition approved July 1, 2005. Published July 2005. Originally approvedin 1969. Last previous edition appr
14、oved in 2002 as D 2839 - 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section ap
15、pears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the density specimen as described in 7.4 and determine the density inaccordance with Test Method D 1505.NOTE 3It has been shown that the measured densit
16、y of an extrudedstrand can be significantly affected by changes in the localized air velocitydue to external drafts, location in relation to HVAC outlets, and so forth.It is advisable to minimize any external airflow and to recognize this whenrelocating instruments or when comparing results from ins
17、truments indifferent locations.7.2 Drop the strand into a 250-mL beaker containing at least200 mL of briskly boiling water, and cover with a watch-glass.Keep a large beaker full of water boiling along with this so thatthe amount of water can be maintained at 200 mL for the wholeperiod without interr
18、upting the boiling. Let the strand conditionin the boiling water for 30 min.NOTE 4A time interval of 5 days at room temperature betweenextrusion of the strand and dropping into boiling water has not been foundcritical.7.3 At the end of the boiling time, remove the beaker fromthe hot plate, making su
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