ASTM D4883-99
(Test Method)Standard Test Method for Density of Polyethylene by the Ultrasound Technique
Standard Test Method for Density of Polyethylene by the Ultrasound Technique
SCOPE
1.1 This test method covers the determination of the density of polyethylene through the utilization of ultrasound equipment.
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Standards Content (Sample)
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Designation: D 4883 – 99
Standard Test Method for
Density of Polyethylene by the Ultrasound Technique
This standard is issued under the fixed designation D 4883; 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.
1. Scope * D 1898 Practice for Sampling of Plastics
D 4703 Practice for Compression Molding Thermoplastic
1.1 This test method covers the determination of the density
Materials into Test Specimens, Plaques, or Sheets
of polyethylene through the utilization of ultrasound equip-
E 691 Practice for Conducting an Interlaboratory Study to
ment.
Determine the Precision of a Test Method
1.2 This test method is based on the distinct behaviors of the
amorphous and crystalline phases of polyethylene in response
3. Terminology
to ultrasound. Polyethylene can be viewed as a composite
3.1 Definitions: The definitions given in Terminology
structure where high-density crystalline regions are connected
D 883, as well as in Test Methods D 792 and D 1505, are
by lower-density amorphous material. The ratio of crystalline
applicable to this test method.
to amorphous material determines the final density of the
material. The amorphous and crystalline phases exhibit very
4. Significance and Use
distinct behaviors with regard to the propagation of sound
4.1 The density of polyethylene is a conveniently measur-
waves. The propagation characteristics in the composite will
able property which is frequently useful as a means of
depend on the relative amount of the two phases (the degree of
following physical changes in a sample, as an indication of
crystallinity).
uniformity among samples, and as a means of identification.
1.3 Inorganic materials increase density as measured by Test
4.2 This test method is designed to yield results with a
Methods D 792 and D 1505, but they have little or no effect on
precision of 60.08 % or better.
ultrasonic density. The ultrasonic measurement is basically a
base resin density.
5. Apparatus
1.4 The values stated in SI units are to be regarded as the
5.1 Use an instrument which utilizes a sonic technique to
standard. The values given in parentheses are for information
evaluate the density of polyethylene. The Tecrad instrument
only.
utilizes a sonic sensing head (transducer) which measures the
1.5 This standard does not purport to address all of the
velocity of sound in a molded specimen, approximately 1.9
safety concerns, if any, associated with its use. It is the
mm in thickness. Because sonic velocity is positively corre-
responsibility of the user of this standard to establish appro-
lated to density in polyethylene, a measurement of this velocity
priate safety and health practices and determine the applica-
can be used to determine specimen density. The information
bility of regulatory limitations prior to use.
from this transducer then must be electronically evaluated; in
NOTE 1—There is no similar or equivalent ISO standard.
the Tecrad instance this is done with a computer, and the result
is reported either through a display or printout.
2. Referenced Documents
5.2 Equipment specified in Test Method D 1505.
2.1 ASTM Standards:
5.3 Equipment specified in Test Methods D 792.
D 618 Practice for Conditioning Plastics and Electrical
5.4 Equipment specified in Practice D 618.
Insulating Materials for Testing
5.5 Equipment specified in Annex A1 of Practice D 4703.
D 792 Test Methods for Density and Specific Gravity (Rela-
2 NOTE 2—The equipment specified in 5.2 or 5.3 is required for the initial
tive Density) of Plastics by Displacement
calibration of the sonic equipment. Once the sonic equipment is calibrated,
D 883 Terminology Relating to Plastics
this additional equipment is no longer required. It is recommended that the
D 1505 Test Method for Density of Plastics by the Density-
standards used for the initial calibration be retained for any additional
Gradient Technique
calibration which may be required. It is also recommended that one or
more of the calibration standards be evaluated on a routine basis for
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods. Annual Book of ASTM Standards, Vol 08.03.
Current edition approved July 10, 1999. Published September 1999. Originally Annual Book of ASTM Standards, Vol 14.02.
published as D 4883 – 89. Last previous edition D 4883 – 96. The Tecrad instrument can be obtained from Tecrad U.S.A., 132 Boston Post
Annual Book of ASTM Standards, Vol 08.01. Rd., East Lyme, CT 06333.
*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.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D4883–99
calibration verification. The absolute accuracy of data produced will be no
8.2 Test Conditions—Conduct tests in the standard labora-
better than this initial calibration and continued verification. Samples for
tory atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 6 5%
initial calibration may be acquired from various standards sources
relative humidity, unless otherwise specified in this test
(National Institute of Standards and Technology, manufacturer, etc.).
method. In cases where between laboratory data disagree, the
tolerances shall be 1°C (1.8°F) and 62 % relative humidity.
6. Test Specimens and Materials
NOTE 6—Testing in normal plant operations frequently calls for testing
6.1 Material for testing shall be acquired by procedures
before the sample can become fully conditioned. It will be necessary to
specified in Practice D 1898.
develop correlations between measured density and conditioning time and
6.2 Test plaques shall be prepared in accordance to the
to apply them to obtain the desired predicted density.
molding procedure specified in Procedure C of Annex A1 of
NOTE 7—Test specimens whose change in density during testing may
Practice D 4703.
be greater than the accuracy required of the density determination shall be
6.3 The test specimen shall consist of a piece of the material
tested under test conditions in accordance with the test method listed in the
under test. The piece may be cut from a molded plaque in the
applicable ASTM specification.
dimensions required for testing. Care should be taken in cutting
9. Procedure (for Tecrad)
specimens to avoid change in density resulting from compres-
sive stress.
9.1 Switch the system on and observe the warm-up count-
Specimen Dimensions, mm (in.)
down.
Length 80–100 (3.15–3.94)
9.2 After the machine has fully stabilized activate the“ F1”
Width 35–45 (1.38–1.77)
function key.
Thickness 1.5–3 (0.06–0.12)
9.3 Insert a sample and enter the sample identification (15
6.4 The specimen shall be free of foreign matter and voids
characters maximum) after the machine displays “Please
and shall have no surface marks or other surface flaws.
specify sample name.”
6.5 The water required by the testing equipment should be
9.4 Wait while the machine displays “Please stand by while
demineralized.
processing.”
9.5 A 10-s countdown will start when “Please remove
7. Calibration
...
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