ASTM D2839-05
(Practice)Standard Practice for Use of a Melt Index Strand for Determining Density of Polyethylene
Standard Practice for Use of a Melt Index Strand for Determining Density of Polyethylene
SIGNIFICANCE AND USE
This practice has been found to be very useful for preparing polyethylene samples suitable for determination of density by Test Method D 1505, 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 which may be a part of a sales contract between the buyer and the seller.
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 D 4703.
Before proceeding with this practice, reference should 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.
SCOPE
1.1 This practice covers the preparation of a sample for polyethylene density determination in accordance with Test Method D 1505. The sample consists of a strand produced by extrusion of the polyethylene in accordance with Test Method D 1238, 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 brackets 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 and health practices and determine the applicability of regulatory limitations prior to use. Note 1—There is no similar or equivalent ISO standard.
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Designation:D2839–05
Standard Practice for
Use of a Melt Index Strand for Determining Density of
1
Polyethylene
This standard is issued under the fixed designation D2839; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 4. Significance and Use
1.1 This practice covers the preparation of a sample for 4.1 This practice has been found to be very useful for
polyethylene density determination in accordance with Test preparing polyethylene samples suitable for determination of
Method D1505. The sample consists of a strand produced by density by Test Method D1505, for quality control purposes,
extrusion of the polyethylene in accordance with Test Method especially in a resin manufacturing facility where fast, repro-
D1238, Condition 190/2.16 (Melt Index). ducible, comparative results are needed. It is not necessarily
1.2 The values stated in SI units are to be regarded as the recommended for resin specifications which may be a part of a
standard.Thevaluesgiveninbracketsareforinformationonly. sales contract between the buyer and the seller.
1.3 This standard does not purport to address all of the 4.2 The density of a polyethylene sample is highly depen-
safety concerns, if any, associated with its use. It is the dent on the preparation and thermal history of the specimens.
responsibility of the user of this standard to establish appro- The level of density results obtained by this practice of sample
priate safety and health practices and determine the applica- preparation differs from that obtained by other methods as
bility of regulatory limitations prior to use. described in Practice D4703.
4.3 Before proceeding with this practice, reference should
NOTE 1—There is no similar or equivalent ISO standard.
be made to the specification of the material being tested. Any
test specimen preparation, conditioning, dimensions, or testing
2. Referenced Documents
2 parameters, or some combination thereof, covered in the
2.1 ASTM Standards:
materials specification shall take precedence over those men-
D1238 Test Method for Melt Flow Rates of Thermoplastics
tioned in this practice. If there are no material specifications,
by Extrusion Plastometer
the default conditions apply.
D1505 Test Method for Density of Plastics by the Density-
Gradient Technique
5. Apparatus
D4703 Practice for Compression Molding Thermoplastic
5.1 Extrusion Plastometer, as described in Test Method
Materials into Test Specimens, Plaques, or Sheets
D1238.
E691 Practice for Conducting an Interlaboratory Study to
5.2 Hot Plate, to boil water.
Determine the Precision of a Test Method
5.3 Beakers, 250-mLlow form, graduated, with watch-glass
covers.
3. Terminology
3.1 Definitions:
6. Sample
3.1.1 melt index strand—theextrudateproducedwhenpoly-
6.1 Polyethylene, in any form suitable for test in accordance
ethylene is extruded in accordance with Test Method D1238,
with Test Method D1238.
Condition 190/2.16.
7. Procedure
1 7.1 Prepare a Melt Index Strand by extruding the sample in
This practice is under the jurisdiction ofASTM Committee D20 on Plastics and
is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials accordance with Test Method D1238, Condition 190/2.16,
(D20.15.01).
dropping the strand on a cool metal plate after cutting off.
Current edition approved July 1, 2005. Published July 2005. Originally approved
When Procedure B of Test Method D1238 is used, cut off the
in 1969. Last previous edition approved in 2002 as D2839 - 02. DOI: 10.1520/
extrudate at about the time the timer is actuated and discard.
D2839-05.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Save the portion extruded during the timed interval.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
NOTE 2—The conditioning procedure as described in 7.2 and 7.3 may
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. be omitted, if desired; in such case, after a 10-min cooling period, cut off
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D2839–05
the density specimen as described in 7.4 and determine the density in TABLE 1 Precision Data
accordance with Test Method D1505. A B C D
Material N Average S S r R
r R
NOTE 3—It has been shown that the measured density of an extruded
B 10 0.9139 0.00026 0.00078 0.00072 0.00219
strand can be significantly affected by changes in the loc
...
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