ASTM D4020-18

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4020 − 11 D4020 − 18
Standard Specification for
Ultra-High-Molecular-Weight Polyethylene Molding and
Extrusion Materials
This standard is issued under the fixed designation D4020; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This specification provides for the identification of virgin, natural color, unmodified homopolymer ultra-high-molecular-
weight polyethylene (UHMW-PE)(UHMWPE) plastics molding and extrusion materials. This identification is made in such a
manner that the seller and purchaser can agree on the acceptability of different commercial lots or shipments.
1.2 This specification also provides guidance for the characterization of UHMWPE materials based on various mechanical,
thermal, electrical, and other analyses.
1.3 It is not intended to differentiate between various molecular weight grades of ultra-high-molecular-weight polyethylene
commercially available.
1.4 It is not the function of this specification to provide specific engineering data for design purposes.
1.5 Ultra-high-molecular-weight polyethylenes, as defined in this specification, are those linear polymers of ethylene which
have a relative viscosity of 1.44 or greater, in accordance with the test procedures described herein.
1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.7 The following precautionary caveat pertains only to the test method portions in Section 7 and the Annex and Appendixes,
of this specification: 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 safety, health, and healthenvironmental practices and
determine the applicability of regulatory limitations prior to use.
NOTE 1—This standard and ISO 11542-1 address the same subject matter, but differ in technical content. ISO 11542-1 provides a classification system
based on various characteristics and a range of viscosity numbers determined in accordance with ISO 1628-3.
NOTE 1—This standard and ISO 11542-1 address the same subject matter, but differ in technical content. ISO 11542-1 provides a classification system
based on various characteristics and a range of viscosity numbers determined in accordance with ISO 1628-3.
1.8 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.
2. Referenced Documents
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D1601 Test Method for Dilute Solution Viscosity of Ethylene Polymers
2.2 ISO Standards:
ISO 11542-1 Plastics—Ultra High Molecular-Weight Polyethylene (PE-UHMW) Moulding and Extrusion Materials—Part 1:
Designation System and Basis for Specification
ISO 1628-3 Plastics—Determination of Viscosity Number and Limiting Viscosity Number—Part 3: Polyethylenes and
Polypropylenes
This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.
Current edition approved Sept. 1, 2011Aug. 1, 2018. Published October 2011August 2018. Originally approved in 1981. Last previous edition approved in 20052011 as
D4020 - 05.D4020 - 11. DOI: 10.1520/D4020-11.10.1520/D4020-18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
*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
D4020 − 18
3. Terminology
3.1 Definitions—Definitions of terms used in this specification are in accordance with Terminology D883.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 ultra-high-molecular-weight polyethylene molding and extrusion materials—as defined by this specification, those
substantially linear polyethylenes which have a relative viscosity of 1.44 or greater, at a concentration of 0.02 %, at 135°C, in
decahydronaphthalene.
3.2.1.1 Discussion—
It has been common practice to refer to the “molecular weight” of UHMW-PEUHMWPE resins. The following calculations shall
be used to approximate the specific viscosity (η ), reduced viscosity (ηred or R.S.V.), intrinsic viscosity (η or I.V.), and the
sp
approximate nominal viscosity average molecular weight of virgin resin. The calculations are shown as follows:
k k
Relative viscosity 5 η 5 t 2 / t 2 (1)
S DS D
r s o
t t
s o
Specific viscosity 5 η 5 η 2 1
sp r
η
sp
Reduced viscosity 5 η 5
red
C
The intrinsic viscosity is calculated by determining the reduced viscosity and extrapolating to infinite dilution, that is, 0 %
concentration.
1/2
Intrinsic viscosity = [η] = (2ηsp − 2 ln ηrel) ÷ c
4 1.37
Nominal viscosity molecular weight = 5.37 × 10 [η]
1⁄2
Intrinsic Viscosity5 η 5 2η 22hlnhη ÷C
f g s d
sp rel
4 1.37
Nominal Viscosity Molecular Weight55.37310 fηg
where:
k = kinetic energy correction constant for the particular viscometer used,
t = flow time of solution at 135°C, s,
s
t = flow time of pure solvent at 135°C, s, and
o
C = concentration.
C = concentration, %.
NOTE 2—There are other equations being used in industry to calculate the nominal viscosity average molecular weights. Refer to Appendix X5X2 for
the other equations and their relationship to the nominal viscosity average molecular weight equation in 3.2.1.1. The equation in 3.2.1.1 is the only
equation that shall be used for reporting of nominal viscosity average molecular weight.
NOTE 3—Use of the solution viscosity test on thermally processed material is invalid due to inadequate solubility and possible crosslinking
4. Classification
4.1 It is recognized that dilute solution viscosity measurements can only be made on virgin resin. Therefore, the following test
and limits shall be used to determine the properties of virgin polymer only.
5. Materials and Manufacture
5.1 The molding and extrusion material shall be UHMWUHMWPE polyethylene in the form of powder or granules.
5.2 The molding and extrusion materials shall be as uniform in composition and size and as free of contamination as can be
achieved by good manufacturing practice. If necessary, the level of contamination shall be agreed upon between the seller and the
purchaser.
5.3 Unless controlled by requirements specified elsewhere in this specification, the color and translucence of molded or extruded
pieces, formed under conditions recommended by the manufacturer of the material, will be comparable within commercial match
tolerances to the color and translucence of standard molded or extruded samples of the same thickness supplied in advance by the
manufacturer of the material.
5.4 Additional test methods and conditions that are commonly used to characterize UHMWPE are listed in Table X4.1.
5.4.1 Refer to Annex A2 for requirements regarding specimen preparation, dimensions, and conditioning requirements for these
tests.
6. Sampling
6.1 A batch or lot shall be considered as a unit of manufacture and can consist of a blend of two or more production runs of
the same material.
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6.2 Unless otherwise agreed upon between the seller and the purchaser, prior to packaging, the material shall be sampled based
on adequate statistical sampling.
7. Test Method
7.1 Dilute Solution Viscosity—Use Test Method D1601, as modified in Annex A1.
8. Keywords
8.1 extrusion materials; molding materials; plastics; polyethylene; ultra-high-molecular-weight; UHMW-PEUHMWPE; vis-
cosity
ANNEXANNEXES
(Mandatory Information)
A1. DILUTE SOLUTION VISCOSITY
A1.1 General Description
A1.1.1 The test sequence consists of dissolving UHMW-PEUHMWPE in decahydronaphthalene (0.02 g/100 mL) at 150°C and
then measuring the relative viscosity at 135°C in an Ubbelohde No. 1 viscometer. It is possible to calculate the relative solution
viscosity from these experimental data.
A1.2. Apparatus
A1.2.1 Analytical Balance.
A1.2.2 Microscope Slide Cover Slip.
A1.2.3 Hot Plate, with magnetic stirrer.
A1.2.4 Erlenmeyer Flask, 250-mL, with glass stopper.
A1.2.5 Vacuum Drying Oven.
A1.2.6 Vacuum Aspirator.
A1.2.7 Viscometer, Ubbelohde No. 1.
A1.2.8 Constant-Temperature Bath, 135 6 0.1°C, with a 305-mm diameter by 460 mm (12 by 18-in.) tall glass jar as a container,
and having a suitable support for the viscometer.
A1.2.9 Buret, 100-mL capacity, 0.1-mL subdivisions.
A1.2.10 Stopwatch, 0.2-s reading.
A1.2.11 Still, for decahydronaphthalene.
A1.2.12 Glass Funnel, with heating mantle.
A1.3. Reagents
A1.3.1 Decahydronaphthalene (Decalin), freshly distilled.
A1.3.2 Tetrakis [methylene 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane (CAS No. 668-19-8).
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NOTE A1.1—This may also be referred to as Tetrakis-(methylene-(3,5-di-(tert)-butyl-4-hydrocinnamate))methane
A1.4. Procedure
A1.4.1 Stabilized Decahydronaphthalene Preparation—Distill in accordance with Test Method D1601 and add 0.2 % tetrakis
[methylene 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane.
A1.4.2 Cleaning the Viscometer—Empty the viscometer thoroughly by vacuum and completely refill the viscometer with distilled,
filtered, non-stabilized decahydronaphthalene. Place the viscometer into the 135°C hot oil constant temperature bath for at least
15-20 min. Completely drain the viscometer and dry with dry air or nitrogen just prior to the next measurement in order to prevent
dilution and an erroneous measurement result.
A1.4.3 Solution Preparation—Dry the UHMW-PEUHMWPE in a vacuum oven for 2 h at 60°C. Weigh 14 to 17 mg of the dry
UHMW-PEUHMWPE onto a slide cover slip. Use the buret to transfer the stabilized decahydronaphthalene at room temperature
into the Erlenmeyer flask, measuring, in millilitres,milliliters, a volume equal to 4.5 times the UHMW-PEUHMWPE weight in
milligrams, for example, 15 mg of UHMW-PEUHMWPE and 67.5 mL of decahydronaphthalene. Heat the decahydronaphthalene,
with stirring, to 150°C, and drop in the UHMW-PEUHMWPE and its slide cover slip. Continue stirring at 150°C for 1 h, with the
flask lightly stoppered.
A1.4.4 Viscosity Measurement:
A1.4.4.1 Place the clean viscometer into the constant-temperature bath, fill with stabilized decahydronaphthalene, and allow the
viscometer and solvent to come to thermal equilibrium at 135 6 0.1°C. Determine the viscosity of the solvent. Clean the
viscometer as directed in A1.4.2. It is essential that the whole viscometer be dry.
A1.4.4.2 Meanwhile, place the flask of polymer solution into the 135°C bath and allow it to equilibrate. Transfer sufficient solution
to fill the viscometer to the mark (see Note A1.2) and determine the viscosity of the solution.
A1.4.4.3 Between uses, clean the viscometer as described in A1.4.2. Prolonged waits between uses (overnight, etc.) will require
the use of the H SO – K Cr O cleaning solution.
2 4 2 2 7
NOTE A1.2—Filling of the viscometer is made easier by the use of a glass funnel warmed with a heating mantle. This helps to prevent the
UHMW-PEUHMWPE from precipitating.
A1.5. Calculation
A1.5.1 Calculate the relative solution viscosity as follows:
η 5 t 2 k/t / t 2 k/t (A1.1)
~ ! ~ !
r s s o o
where:
k = kinetic energy correction constant for the particular viscometer used,
t = flow time of solution at 135°C, and
s
t = flow time of pure solvent at 135°C.
o
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APPENDIXES
(Nonmandatory Information)
X1. CHARACTERIZATION OF ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE
X1.1 Scope
X1.1.1 The following appendixes provide guidance for the characterization of UHMW-PE based on various mechanical, thermal,
electrical, and other analyses.
A2. TEST SPECIMEN PREPARATION, DIMENSIONS, AND CONDITIONING REQUIREMENTS
A2.1 Test Specimens
A2.1.1 Test specimen sheets shall be prepared from powder or granules and molded in accordance with the following conditions.
Molding pressure 6.9 to 10.3 MPa
Platen temperature 196 to 210°C
Heating time 20 min at 196 to 210°C
Platen cooling rate 15 ± 2°C/min from 150 to 90°C
Below 90°C Maintain pressure and cool as quickly as possible to <30°C
Platen temperature for demolding <30°C
A2.2 Specimen Dimensions
A2.2.1 Specimen dimensions shall conform to the requirements of the individual tests.
A2.3 Conditioning
A2.3.1 Condition the notched specimens at 23 6 2°C for not less than 16 h prior to test.
A2.4 Test Conditions
A2.4.1 Conduct the test in the standard laboratory atmosphere of 23 6 2°C.
X2. IMPACT TEST METHOD FOR ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE
X2.1. Scope
X2.1.1 This test method covers determination of the impact strength of UHMW-PE, which is extremely impact resistant. When
tested in accordance with Test Method D256, Method A, UHMW-PE generally gives the NBF type of failure, rendering the test
result invalid. This test method specifies the same type of pendulum impact test machine as that given in Test Method D256 but
introduces a much higher degree of stress concentration into the specimen by double notching with a razor blade. Application of
this test method shall be limited to the characterization of virgin, unmodified UHMW-PE resins, not commercially processed
products. It is advised that the user be familiar with Test Method D256 before attempting to use this test method.
X2.1.2 The values stated in SI units are to be regarded as the standard.
NOTE X2.1—This test method and Annex B of ISO 11542-2 address the same subject matter, but differ in technical content and results shall not be
compared between the two test methods.
D4020 − 18
X2.2. Referenced Documents
X2.2.1 ASTM Standards:
D256 Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
X2.2.2 ISO Standards:
ISO 180-1982 (E) Determination of Izod Impact Strength of Rigid Materials
ISO 11542-2 Plastics—Ultra-High Molecular Weight Polyethylene (PE-UHMW) Moulding and Extrusion Materials—Part 2:
Preparation of Test Specimens and Determination of Properties
X2.3. Apparatus
X2.3.1 The Izod-type impact machine that conforms to the requirements of Test Method D256, including the calibration and
checking methods, shall be used.
X2.4. Test Specimen
X2.4.1 The geometry and dimensions of the specimen are given in Fig. X2.1.
X2.4.2 The specimens shall be cut from a sheet compression molded in accordance with the conditions described in Table X2.1:
TABLE X2.1 Molding Conditions for UHMW-PE Impact Test Specimens
Molding pressure 6.9 to 10.3 MPa
Platen temperature 196 to 210°C
Heating time 20 min at 196 to 210°C
Platen cooling rate 15 ± 2°C/min from 150 to 90°C
Platen temperature for demolding <30°C
X2.4.3 The width of the specimen shall be the thickness of the sheet if the sheet thickness is within 6.00 to 6.75 mm. Sheet
material thicker than 6.75 mm shall be machined down to 6.35 6 0.25 mm. Sheet material thicker than 7.65 mm shall not be used.
X2.4.4 Each specimen shall be free of twist and shall be bounded by mutually perpendicular pairs of plane parallel surfaces, free
from scratches, pits, and sink marks.
X2.5 Notching of Specimens
X2.5.1 Notching shall be performed on the side parallel to the direction of the application of molding pressure.
X2.5.2 Notching shall be performed in a suitable machine by pressing in a 0.23 6 0.03-mm thick single-edge razor blade with
a 14 6 2° included angle at the cutting edge. The notching speed shall be less than 500 mm/min. A new blade shall be used after
notching 40 specimens.
X2.5.3 The calibration of the notching machine shall be checked by direct measurement of the notch depth, perpendicularity, and
offset of the two notches. One of the possible measurement methods is given in Appendix X3.
X2.6. Conditioning
X2.6.1 Conditioning—Condition the notched specimens at 23 6 2°C for not less than 40 h prior to test.
X2.6.2 Test Conditions—Conduct the test in the standard laboratory atmosphere of 23 6 2°C.
X2.7. Procedure
X2.7.1 At least five and preferably ten individual determinations of impact value must be made on each sample to be tested under
the conditions prescribed in X2.6.
X2.7.2 Measure the width of each specimen in the region of the notches twice with a micrometer to the nearest 0.025 mm, and
D4020 − 18
record its average width. Use an optical microscope to measure the distances between the notch roots on the two side surfaces of
the specimen. Record the average value and multiply this number by the width of the specimen to obtain the remaining unnotched
cross-section area, AR. Also record the identifying markings of the specimen.
X2.7.3 Estimate the breaking energy for the specimen and select a pendulum of suitable energy. Start the test with a pendulum
of 11 J if no prior test data are available. Use the lightest standard pendulum that is expected to break each specimen in the group
with a loss of not more than 85 % of its energy.
X2.7.4 Before testing the specimens, perform the following operations on the machine:
X2.7.4.1 With the excess energy indicating pointer in its normal starting position, but without a specimen in the vise, release the
pendulum from its normal starting position and note the position that the pointer attains after the swing as one reading of Factor
A.
X2.7.4.2 Without resetting the pointer, raise the pendulum and release again, which will move the pointer up the scale an
additional amount. Repeat this step if the pointer does not move. Repeat this procedure until a swing causes no additional
movement of the pointer, and note the final reading as one reading of Factor B.
X2.7.4.3 Repeat the above two operations several times, and calculate and record the average A and B readings.
X2.7.5 Position the specimen precisely and rigidly but not clamped too tightly in the vise. The relationship of the vise, specimen,
and striking edge of the pendulum to one another is given in Fig. X2.2. Note that the top plane of the vise shall be 0.13 6 0.13
mm below the notches.
X2.7.6 Release the pendulum and note and record the excess energy remaining in the pendulum after breaking the specimen.
X2.7.7 From the breaking strength of the specimen and Factors A and B, determine the energy loss of the pendulum due to
windage and friction using the correction charts from the commercial testing machine supplier. If these charts are not available,
use the method given in Appendix X2 or X3 of Test Method D256. Subtract the correction so calculated from the indicated
breaking strength of the specimen. If a pendulum of improper energy was used, discard the result and make additional tests on new
specimens with the proper pendulum. If the proper pendulum was used, divide the net value so found by the unnotched area AR
of the specimen as measured in X2.7.2 to obtain its impact strength in kilojoules per square metre.
X2.7.8 Record the type of failure for each specimen as one of the two coded categories defined as follows:
(1) C, Complete Break—A break in which the specimen separates into two pieces.
(2) NB, Non-Break—A break in which the specimen does not separate into two pieces.
X2.7.9 Calculate the average impact strength and standard deviation of the group of specimens that results in complete breakage.
This test method requires that the specimen breaks completely. The results obtained from unbroken specimens shall be considered
a departure from standard and shall not be reported as a standard result.
X2.8. Report
X2.8.1 Report the following information:
X2.8.2 Complete identification of the material tested, including type, source, manufacturer’s lot number, and previous history;
X2.8.3 Compression molding conditions;
X2.8.4 Capacity of the pendulum, J;
X2.8.5 Total number of specimens tested;
X2.8.6 Number of those specimens that result in complete break;
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X2.8.7 Average impact strength, kJ/m ;
X2.8.8 Standard deviation; and
X2.8.9 Percent of specimens failing in each category, suffixed by the corresponding letter code from X2.7.8.
X2.9. Precision and Bias
X2.9.1 Table X2.2 is based on a round robin conducted by seven laboratories. For each material, all of the test specimens were
compression molded and machined at one source. Each participating laboratory notched and tested five specimens of each material.
X2.9.1.1 Repeatability, I (Comparing two test results for the same material, obtained by the same operator using the same
r
equipment on the same day)—The two test results are judged not equivalent if they differ by more than the I value for that material.
r
X2.9.1.2 Reproducibility, I (Comparing two test results for the same material, obtained by different operators using different
R
equipment on different days)—The two test results are judged not equivalent if they differ by more than the I value for that
R
material.
A3. IMPACT TEST METHOD FOR ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE
A3.1 Scope
A3.1.1 This test method covers determination of the impact strength of UHMWPE, which is extremely impact resistant. When
tested in accordance with Test Method D256, Method A, UHMWPE generally gives the NBF type of failure, rendering the test
result invalid. This test method specifies the same type of pendulum impact test machine as that given in Test Method D256 but
introduces a much higher degree of stress concentration into the specimen by double notching with a razor blade. Application of
this test method shall be limited to the characterization of virgin, unmodified UHMWPE resins, not commercially processed
products. It is advised that the user be familiar with Test Method D256 before attempting to use this test method.
A3.1.2 The values stated in SI units are to be regarded as the standard.
NOTE A3.1—This test method and Annex B of ISO 11542-2 address the same subject matter, but differ in technical content and results shall not be
compared between the two test methods.
A3.2. Referenced Documents
A3.2.1 ASTM Standards:
D256 Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
A3.2.2 ISO Standards:
ISO 180 Determination of Izod Impact Strength of Rigid Materials
ISO 11542-2 Plastics—Ultra-High Molecular Weight Polyethylene (PE-UHMW) Moulding and Extrusion Materials—Part 2:
Preparation of Test Specimens and Determination of Properties
A3.3. Apparatus
A3.3.1 The Izod-type impact machine that conforms to the requirements of Test Method D256, including the calibration and
checking methods, shall be used.
A3.4. Test Specimen
A3.4.1 The geometry and dimensions of the specimen are given in Fig. A3.1.
A3.4.2 The specimens shall be cut from a sheet compression molded in accordance with the conditions described in A2.1.
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A = 6.7/6.0 Θ 90 ± 2°
B = 12.8/12.6
C = 32.0/31.5
D = 64.0/63.0
E = 4.60/4.50
F = ±0.10
mm in.
A 6.35 ± 0.38 A 0.250 ± 0.015
B 12.70 ± 0.10 B 0.500 ± 0.004
C 31.75 ± 0.25 C 1.250 ± 0.010
D 63.50 ± 0.38 D 2.500 ± 0.015
E 4.57 ± 0.08 E 0.180 ± 0.003
F 0.00 ± 0.13 F 0.000 ± 0.005
θ 90° ± 2° θ 90° ± 2°
FIG. X2.1A3.1 Dimensions of Double-Notched Izod Test Specimens
A3.4.3 The width of the specimen shall be the thickness of the sheet if the sheet thickness is within 6.00 to 6.75 mm. Sheet
material thicker than 6.75 mm shall be machined down to 6.35 6 0.25 mm. Sheet material thicker than 7.65 mm shall not be used.
A3.4.4 Each specimen shall be free of twist and shall be bounded by mutually perpendicular pairs of plane parallel surfaces, free
from scratches, pits, and sink marks.
A3.5 Notching of Specimens
A3.5.1 In the case of compression molding, the two notches (or width of two notches) shall be perpendicular to the direction of
application of molding pressure: if applicable. The impact resistance of a plastic material may be different if the notch is
perpendicular to, rather than parallel to, the direction of molding. The same is true for specimens cut with or across the grain of
an anisotropic sheet or plate.
A3.5.2 Notching shall be performed in a suitable machine by pressing in a 0.23 6 0.03-mm thick single-edge razor blade with
a 14 6 2° included angle at the cutting edge. The notching speed shall be less than 500 mm/min. A new blade shall be used after
notching 40 specimens.
A3.5.3 The calibration of the notching machine shall be checked by direct measurement of the notch depth, perpendicularity, and
offset of the two notches. One of the possible measurement methods is given in Annex A4.
A3.6. Conditioning
A3.6.1 Conditioning—Condition the notched specimens at 23 6 2°C for not less than 16 h prior to test.
A3.6.2 Test Conditions—Conduct the test in the standard laboratory atmosphere of 23 6 2°C.
A3.7. Procedure
A3.7.1 At least five and preferably ten individual determinations of impact value must be made on each sample to be tested under
the conditions prescribed in A3.6.
A3.7.2 Measure the width of each specimen in the region of the notches twice with a micrometer to the nearest 0.025 mm, and
record its average width. Use an optical microscope to measure the distances between the notch roots on the two side surfaces of
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the specimen. Record the average value and multiply this number by the width of the specimen to obtain the remaining unnotched
cross-section area, AR. Also record the identifying markings of the specimen.
A3.7.3 Estimate the breaking energy for the specimen and select a pendulum of suitable energy. Start the test with a pendulum
of 11 J if no prior test data are available. Use the lightest standard pendulum that is expected to break each specimen in the group
with a loss of not more than 85 % of its energy.
A3.7.4 Before testing the specimens, perform the following operations on the machine:
A3.7.4.1 With the excess energy indicating pointer in its normal starting position, but without a specimen in the vise, release the
pendulum from its normal starting position and note the position that the pointer attains after the swing as one reading of Factor
A.
A3.7.4.2 Without resetting the pointer, raise the pendulum and release again, which will move the pointer up the scale an
additional amount. Repeat this step if the pointer does not move. Repeat this procedure until a swing causes no additional
movement of the pointer, and note the final reading as one reading of Factor B.
A3.7.4.3 Repeat the above two operations several times, and calculate and record the average A and B readings.
A3.7.5 Position the specimen precisely and rigidly but not clamped too tightly in the vise. The relationship of the vise, specimen,
and striking edge of the pendulum to one another is given in Fig. A3.2. Note that the top plane of the vise shall be 0.13 6 0.13
mm below the notches.
A3.7.6 Release the pendulum and note and record the excess energy remaining in the pendulum after breaking the specimen.
A3.7.7 From the breaking strength of the specimen and Factors A and B, determine the energy loss of the pendulum due to
windage and friction using the correction charts from the commercial testing machine supplier. If these charts are not available,
use the method given in Appendix X2 or X3 of Test Method D256. Subtract the correction so calculated from the indicated
breaking strength of the specimen. If a pendulum of improper energy was used, discard the result and make additional tests on new
specimens with the proper pendulum. If the proper pendulum was used, divide the net value so found by the unnotched area AR
of the specimen as measured in A3.7.2 to obtain its impact strength in kilojoules per square meter.
A3.7.8 Record the type of failure for each specimen as one of the two coded categories defined as follows:
FIG. X2.2A3.2 Relationship of Vise, Specimen, and Strike Edge to One Another
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(1) C, Complete Break—A break in which the specimen separates into two pieces.
(2) NB, Non-Break—A break in which the specimen does not separate into two pieces.
A3.7.9 Calculate the average impact strength and standard deviation of the group of specimens that results in complete breakage.
This test method requires that the specimen breaks completely. The results obtained from unbroken specimens shall be considered
a departure from standard and shall not be reported as a standard result.
A3.8. Report
A3.8.1 Report the following information:
A3.8.2 Complete identification of the material tested, including type, source, manufacturer’s lot number, and previous history;
A3.8.3 Compression molding conditions;
A3.8.4 Capacity of the pendulum, J;
A3.8.5 Total number of specimens tested;
A3.8.6 Number of those specimens that result in complete break;
A3.8.7 Average impact strength, kJ/m ;
A3.8.8 Standard deviation; and
A3.8.9 Percent of specimens failing in each category, suffixed by the corresponding letter code from A3.7.8.
A3.9. Precision and Bias
A3.9.1 Table A3.1 is based on a round robin conducted by seven laboratories. For each material, all of the test specimens were
compression molded and machined at one source. Each participating laboratory notched and tested five specimens of each material.
A3.9.1.1 Repeatability, I (Comparing two test results for the same material, obtained by the same operator using the same
r
equipment on the same day)—The two test results are judged not equivalent if they differ by more than the I value for that material.
r
A3.9.1.2 Reproducibility, I (Comparing two test results for the same material, obtained by different operators using different
R
equipment on different days)—The two test results are judged not equivalent if they differ by more than the I value for that
R
material.
X3. MEASUREMENT METHOD OF IMPERFECTIONS IN SPECIMEN NOTCHING
TABLE X2.2A3.1 Precision of the Double-Notched Izod Impact
Test Method
Intrinsic
Values, kJ/m
Material Viscosity,
A B C D
Mean S S I I
dl/g r R r R
A 24 128.0 6.5 27.6 18.4 78.2
B 27 120.0 5.4 25.8 15.2 73.1
C 22 103.9 4.1 21.2 11.6 59.9
D 28 56.1 2.2 9.6 6.2 27.2
E 25 63.5 2.7 12.6 7.7 35.5
A
S = within-laboratory standard deviation of the average.
r
B
S = between-laboratories standard deviation of the average.
R
C
I = 2.83 S .
r r
D
I = 2.83 S .
R R
D4020 − 18
X3.1 The following is one of the possible test methods for measuring the imperfections in specimen notching directly, which can
be classified into three kinds: (1) deviation from perpendicularity, (2) incorrect notch-depth, and (3) offset of notches (Fig. X3.1).
NOTE X3.1—There is no known ISO equivalent to this method.
X3.2 Apparatus
X3.2.1 Reflective Optical Microscope, ocular, 40 to 60×, with an X-Y stage accurate to 0.0025 mm.
X3.2.2 Eyepiece, with a crosshair.
X3.2.3 Fiber Optic Illumination.
X3.3 Procedure
X3.3.1 Lay the specimen on one of its sides and mount it securely on the X-Y stage.
X3.3.2 The beginning and ending points of the notches are labeled from A to D in Fig. X3.1. Select one of the edges of the
¯
specimen as the datum line from which the perpendicularity of the notches to the edges is measured (in this case Line AE). Note
that Point E is approximately 6.4 mm from Point A.
X3.3.3 Keep both the microscope and the base of the X-Y stage stationary. Measure the coordinates of Points A to E with respect
to an arbitrarily selected coordinate system by moving the X-Y stage and by targeting the points by the crosshair of the eyepiece.
X3.4 Calculation
X3.4.1 The following equation is used to calculate the perpendicularity of the notches:
m 2 m
2 1
/EAB 5 tan (X3.1)
11m m
2 1
where:
¯ ¯
m andm =
slopes of line AE and AB with respect to the coordinate system.
1 2
m and m are calculated from
1 2
y 2 y
2 1
m 5 (X3.2)
x 2 x
2 1
where:
m = slope, and
(x , y ) and (x , y ) = coordinates of the end points of the line.
1 1 2 2
The distance between two points, I, is obtained from the following equation:
2 2
I 5= x 2 x 1 y 2 y
~ ! ~ !
2 1 2 1
The amount of offset of the notches is calculated from the following equation:
offset 5 AD? cos /DAE (X3.4)
?
D4020 − 18
A4. MEASUREMENT METHOD OF IMPERFECTIONS IN SPECIMEN NOTCHING
A4.1 The following is one of the possible test methods for measuring the imperfections in specimen notching directly, which can
be classified into three kinds: (1) deviation from perpendicularity, (2) incorrect notch-depth, and (3) offset of notches (Fig. A4.1).
NOTE A4.1—There is no known ISO equivalent to this method.
A4.2 Apparatus
A4.2.1 Reflective Optical Microscope, ocular, 40 to 60×, with an X-Y stage accurate to 0.0025 mm.
A4.2.2 Eyepiece, with a crosshair.
A4.2.3 Fiber Optic Illumination.
A4.3 Procedure
A4.3.1 Lay the specimen on one of its sides and mount it securely on the X-Y stage.
FIG. X3.1A4.1 Notch Geometry of Double-Notched Izod Specimen
D4020 − 18
A4.3.2 The beginning and ending points of the notches are labeled from A to D in Fig. A4.1. Select one of the edges of the
¯
specimen as the datum line from which the perpendicularity of the notches to the edges is measured (in this case Line AE). Note
that Point E is approximately 6.4 mm from Point A.
A4.3.3 Keep both the microscope and the base of the X-Y stage stationary. Measure the coordinates of Points A to E with respect
to an arbitrarily selected coordinate system by moving the X-Y stage and by targeting the points by the crosshair of the eyepiece.
A4.4 Calculation
A4.4.1 The following equation is used to calculate the perpendicularity of the notches:
m 2 m
2 1
/EAB 5 tan (A4.1)
11m m
2 1
where:
¯ ¯
m andm =
slopes of line AE and AB with respect to the coordinate system.
1 2
m and m are calculated from
1 2
y 2 y
2 1
m 5 (A4.2)
x 2 x
2 1
where:
m = slope, and
(x , y ) and (x , y ) = coordinates of the end points of the line.
1 1 2 2
The distance between two points, I, is obtained from the following equation:
2 2
=
I 5 ~x 2 x ! 1~y 2 y ! (A4.3)
2 1 2 1
The amount of offset of the notches is calculated from the following equation:
offset 5 AD? cos /DAE (A4.4)
APPENDIXES
?
(Nonmandatory Information)
X1. ELONGATIONAL STRESS TEST METHOD FOR ULTRA-HIGH MOLECULAR-WEIGHT POLYETHYLENE
X4.1. Scope
X4.1.1 This test method covers the determination of elongational stress as a characterization of the melt viscosity of UHMW-PE.
The melt flow rate in accordance with test method D1238 cannot be determined for this material because ultra high molecular
weight polyethylene does not have a melt flow. The elongational stress is also be referred to as ZST and flow value, or both.
X4.1.2 Application of this test method shall be limited to virgin, unmodified resin. The elongational stress method is invalid on
a previous thermally-processed material due to possible crosslinking.
NOTE X4.1—This test method is identical to to Annex A of ISO 11542-2 in the measurement of elongational stress. It is not equivalent to ISO 11542-2
in any other measurement or section
X1.1 Scope
X1.1.1 This test method covers the determination of elongational stress as a characterization of the melt viscosity of UHMWPE.
The melt flow rate in accordance with test method D1238 cannot be determined for this material because ultra high molecular
weight polyethylene does not have a melt flow. The elongational stress is also be referred to as ZST and flow value, or both.
D4020 − 18
X1.1.2 Application of this test method shall be limited to virgin, unmodified resin. The elongational stress method is invalid on
a previous thermally-processed material due to possible crosslinking.
NOTE X1.1—This test method is identical to to Annex A of ISO 11542-2 in the measurement of elongational stress. It is not equivalent to ISO 11542-2
in any other measurement or section
X1.2. Referenced Documents
X1.2.1 ASTM Standards:
D4703 Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or Sheets
X1.2.2 ISO Standards:
ISO 11542–2 Plastics – Ultra-high-molecular-weight polyethylene (PE-UHMW) Moulding and Extrusion – Part 2: Preparation
of test specimens and determination of properties
X1.3. Terminology
X1.3.1 elongational stress—(in MPa) the tensile stress (force related to the initial cross-sectional area) required to elongate a test
specimen 600 % in a hot oil bath at 150°C in a 10–min time period.
X1.3.2 tensile stress—(in MPa) the attached weight corrected for the buoyancy effect divided by the measured initial
cross-sectional area.
X1.4. Apparatus
X1.4.1 Specimen die cutter
X1.4.2 Specimen holder in accordance with Fig. X4.1X1.1
X1.4.3 Constant temperature bath with thermoregulator and circulating pump
X1.4.4 Graduated weight set with hooks for suspension from the specimen holder. Recommended weights are approximately 700,
650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 180, 150, 120, and 100 g.
X1.4.5 Measuring instrument capable of measuring to 0.02 mm
X1.4.6 Stopwatch
X1.4.7 Hot bath liquid (for example, silicone oil)
X1.4.8 Compression molding press with controlled rate of cooling of 15 6 2°C/min
X1.4.9 Positive compression mold with a minimum of 4 grooves for venting and minimization of residual stress and warpage.
Capable of molding plaque or disk 1.4 mm in thickness.
X1.4.10 Aluminum foil
FIG. X4.1X1.1 Test Specimen
D4020 − 18
X1.4.11 Analytical balance, accurate to 60.1 g
X1.4.12 Blender, high intensity
X1.5. Reagents
X1.5.1 The addition of a mixture of a primary and secondary antioxidant to reduce the amount of crosslinking taking place in the
specimens. The type and amount of antioxidant used will depend on the lab and the R value observed when results are calculated.
NOTE X1.2—A blend of Tris(2,4-di-(tert)butylphenyl)phosphite (CAS No. 31570-0404) and Tetrakis [methylene 3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)
propionate] methane (CAS No. 6683-19-8) at a 2:1 or 1:1 ratio has been found to work well when added at between 0.4 and 0.75 % by weight.
X1.6. Procedure
X1.6.1 Test Plaque Preparation:
X1.6.1.1 Using the analytical balance weigh out the amount of UHMW-PEUHMWPE virgin material that will be needed to mold
the number of plaques or disks required for the study. Based on the amount of UHMW-PEUHMWPE weighed, weigh the amount
of antioxidant necessary to achieve a concentration capable of reducing crosslinking. With the high intensity blender, mix the
antioxidant homogeneously into the UHMW-PE.UHMWPE.
X1.6.1.2 Place the bottom half of the positive mold on a flat surface. Cover the bottom half with a piece of aluminum foil. Weigh
out the amount of the UHMW-PE/antioxidantUHMWPE/antioxidant mix necessary to fill the mold, make a full part, and minimize
flash and warpage. When this weight is established, this weight 60.1 g shall be used consistently to ensure uniform moldings. Pour
the weighed polymer into the mold cavity and spread it out into a smooth level surface. Cover with a second piece of aluminum
foil, then the upper portion of the positive compression mold.
X1.6.1.3 A completely fused test plaque is prepared by compression molding. The following molding conditions are proposed as
guidelines: 1) 200°C under 12.7 MPa pressure for 20 min, 2) cool under pressure at a cooling rate of 15 6 2°C/min and 3) when
the plaque or disk has cooled to below 40°C, remove it from the mold.
X1.6.2 Test Specimens—Six specimens in accordance with Fig. X4.2X1.2 shall be die cut out of one test plaque. Each specimen
is tested using a different weight as described in X4.6.4.4X1.6.4.4.
X1.6.3 Measurement of Cross-sections—The width and thickness at the narrow parallel-sided section of each of the six specimens
shall be measured and recorded to the nearest 0.02 mm.
X1.6.4 Elongational Stress Determination
X1.6.4.1 Stabilize the bath at 150 6 2°C.
X1.6.4.2 Insert test specimen in the holder, hook the corresponding weight to the holder and suspend in bath. The mass of the
holder and weights shall be known to an accuracy of 0.1 g.
X1.6.4.3 After preheating five min, elongate specimen and record specimen elongation time. The elongation of test specimens
does not take place at constant speed.
X1.6.4.4 Repeat for the remaining specimens. The choice of the six different weights used to load test specimens from the weights
listed in X4.4.4X1.4.4 depends upon the molecular weight of the UHMW-PEUHMWPE sample. The weights shall be selected so
that a time of 1 to 20 min gives 600 % elongation in the narrow parallel-sided section of the test specimen.
X1.7. Calculation
X1.7.1 The tensile stress in MPa on each individual specimen is calculated in accordance with the following equation:
T 5 M 1M 30.00981 /A 3B 3 12 ρ /ρ (X1.1)
$@~ ! # % @ ~ !#
S 1 2 1 1 m w
D4020 − 18
FIG. X4.2X1.2 Specimen Holder
T = Tensile stress in MPa
S
M = Mass of selected weight
M = Mass of specimen holder
A = Initial thickness of test specimen (mm)
B = Initial width of test specimen (mm)
ρ = Density of the heat bath medium at 150°C
m
ρ = Density of the metal at 150°C
w
Use log/log scale to plot tensile stress for the six specimens against corresponding times for the 600 % elongation recorded in
X4.6.4.4X1.6.4.4. Draw a best fit line through the six points and from this graph, read off the tensile stress corresponding to a
period of 10 min. This value represents the elongational stress in MPa.
NOTE X1.3—An undue amount of scatter (R ≤ 0.95) or zero elongation indicates that crosslinking has occurred in the test specimens. If this occurs, repeat
the test using specimens prepared using an increased amount of stabilizer. Increase the stabilizer level at least 50 % from what was previously used.
X1.8. Precision
X1.8.1 The repeatability standard deviation has been determined to be 0.009 MPa for a material having an average elongational
stress value of 0.516 MPa. This is based on a single laboratory making 45 measurements over a period of time on one material.
The reproducibility of this test method is not yet available.
D4020 − 18
X2. NOMINAL VISCOSITY AVERAGE MOLECULAR WEIGHT OF ULTRA-HIGH MOLECULAR-WEIGHT POLYETHYLENE
X5.1. Scope
X5.1.1 The measurement of molecular weight of UHMW-PE is nearly impossible to measure by techniques normally used to
measure molecular weight of other polymers. Techniques such as gel permeation chromatography (GPC) and light scattering used
for other polymers are not useful for UHMW-PE.
X5.1.2 The dilute viscosity test method can provide satisfactory correlations for viscosity average molecular weight within a
specific manufacturing process, but this does not necessarily apply for another manufacturing process. As a result, at least five
equations have been developed to describe the molecular weight of UHMW-PE.
X5.1.3 Fig. X5.1 shows the relationship between the five equations with respect to nominal viscosity average molecular weight
versus intrinsic viscosity.
X5.1.4 This appendix is being provided only as a reference. Only Eq 1 listed in 3.2.1.1 of this specification shall be used to present
data to the industry.
FIG. X5.1X2.1 Known Molecular Weight Equations (Correlating with Intrinsic Viscosity)
D4020 − 18
X2.1 Scope
X2.1.1 The measurement of molecular weight of UHMWPE is nearly impossible to measure by techniques normally used to
measure molecular weight of other poly
...