ASTM D4894-19

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: D4894 − 15 D4894 − 19
Standard Specification for
Polytetrafluoroethylene (PTFE) Granular Molding and Ram
Extrusion Materials
This standard is issued under the fixed designation D4894; 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*
1.1 This specification covers granular resins and test methods for polytetrafluoroethylene (PTFE) that have never been
preformed or molded and are normally processed by methods similar to those used in powder metallurgy or ceramics, or by special
extrusion processes. These PTFE resins are homopolymers of tetrafluoroethylene, or, in some cases, modified homopolymers
containing not more than one percent by weight of other fluoromonomers. The usual methods of processing thermoplastics
generally are not applicable to these materials because of their viscoelastic properties at processing temperatures. The materials
included herein do not include mixtures of PTFE resin with additives such as colorants, fillers or plasticizers; nor do they include
reprocessed or reground resin or any fabricated articles. The methods and properties included are those required to identify the
various types of resins. Additional procedures are provided in the Appendix for further characterization of the resins.
1.2 The values stated in SI units as detailed in IEEE/ASTM SI-10 are to be regarded as the standard, and the practices of
IEEE/ASTM SI-10 are incorporated herein.
1.3 The following precautionary caveat pertains only to the Specimen Preparation section, Section 9, and the Test Methods
section, Section 10, of this specification: This specification 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. See Notes 3 and 9 for specific cautionary statements.
NOTE 1—Information in this specification is technically equivalent to related information in ISO 12086-1 and ISO 12086-2.
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.
2. Referenced Documents
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D1708 Test Method for Tensile Properties of Plastics by Use of Microtensile Specimens
D1895 Test Methods for Apparent Density, Bulk Factor, and Pourability of Plastic Materials
D3295 Specification for PTFE Tubing, Miniature Beading and Spiral Cut Tubing
D3892 Practice for Packaging/Packing of Plastics
D4441 Specification for Aqueous Dispersions of Polytetrafluoroethylene
D4591 Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by Differential Scanning
Calorimetry
D4745 Classification System and Basis for Specification for Filled Polytetrafluoroethlyene (PTFE) Molding and Extrusion
Materials Using ASTM Methods
D4895 Specification for Polytetrafluoroethylene (PTFE) Resin Produced From Dispersion
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
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 May 1, 2015May 1, 2019. Published June 2015June 2019. Originally approved in 1989. Last previous edition approved in 20122015 as
D4894 - 07D4894 - 15.(2012). DOI: 10.1520/D4894-15.10.1520/D4894-19.
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.
*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
D4894 − 19
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
IEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System
2.2 ISO Standards:
ISO 12086-1 Plastics—Fluoropolymer Dispersions and Moulding and Extrusion Materials—Part 1: Designation System and
Basis for Specification
ISO 12086-2 Test Methods for Fluoropolymers
3. Terminology
3.1 Definitions:
3.1.1 The terminology given in Terminology D883 is applicable to this specification.
3.2 Descriptions of Terms Specific to This Standard:
3.2.1 bulk density—the mass (in grams) per litreliter of resin measured under the conditions of the test.
3.2.2 extended specific gravity (ESG)—the specific gravity of a specimen of PTFE material molded as described in this
specification and sintered (g.v.) for an extended period of time, compared to the sintering time for the measurement of standard
specific gravity (SSG), using the appropriate sintering schedule given in this specification.
3.2.3 lot, n—one production run or a uniform blend of two or more production runs.
3.2.4 preforming—compacting powdered PTFE material under pressure in a mold to produce a solid object, called a preform,
that is capable of being handled. Molding and compaction are terms used interchangeably with preforming for PTFE.
3.2.5 reground resin—that produced by grinding PTFE material that has been preformed but has never been sintered.
3.2.6 reprocessed resin—that produced by grinding PTFE material that has been both preformed and sintered.
3.2.7 sintering—as it applies to PTFE, a thermal treatment during which the PTFE is melted and recrystallized by cooling with
coalescence occurring during the treatment.
3.2.8 skiving—a machining operation during which a continuous film of PTFE material is peeled from the lateral surface of a
cylindrical sintered molding.
3.2.9 standard specific gravity (SSG)—the specific gravity of a specimen of PTFE material molded as described in this
specification and sintered using the appropriate sintering schedule given in this specification.
3.2.10 thermal instability index (TII)—a measure of the decrease in molecular weight of PTFE material which has been heated
for a prolonged period of time.
4. Classification
4.1 This specification covers the following six types of PTFE generally used for compression molding or ram extrusion, or both:
4.1.1 Type I—Resin used for general-purpose molding and ram extrusion.
4.1.2 Type II—Finely divided resin with an average particle size less than 100 micrometres.
4.1.3 Type III—Modified resins, either finely divided or free-flowing, typically used in applications requiring improved
resistance to creep and stress-relaxation in end-use.
4.1.4 Type IV—Free-flowing resins. Generally made by treatment of finely divided resin to produce free-flowing agglomerates.
4.1.5 Type V—Presintered. Resin that has been treated thermally at or above the melting point of the resin at atmospheric
pressure without having been previously preformed.
4.1.6 Type VI—Resin, not presintered, but for ram extrusion only.
NOTE 2—See Tables 1 and 2 for division of Types by Grades, and footnotes to Tables 1 and 2 (and Table X2.1 in Appendix X2.) for former
classifications.
4.2 A line callout system is used to specify materials in this standard. The system uses predefined cells to refer to specific aspects
of this specification, illustrated as follows:
Specification
Standard Number Block : Type : Grade : Class : Special notes
: : : : :
Example: ASTM
III 2
D4894 – 04
For this example, the line callout would be ASTM D4894 – 04, III2, and would specify a granular polytetrafluoroethylene that
has all of the properties listed for that Type and Grade in the appropriate specified properties, Tables, or both, in this specification.
In this case there is no Class item so the cell position for class is left blank. A comma is used as the separator between Standard
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D4894 − 19
A
TABLE 1 Detail Requirements for Tests on Resins
Type Grade Bulk Density, g/L Particle Size, Average Diameter, μm Water Content, max, % Melting Peak Temperature
Initial °C Second °C
A
I 1 700 ± 100 500 ± 150 0.04 327 ± 10
A
2 675 ± 50 375 ± 75 0.04 327 ± 10
A
II . . . . . . <100 0.04 327 ± 10
A
III 1 400 ± 125 <100 0.04 327 ± 10
A
2 850 ± 100 500 ± 150 0.04 327 ± 10
A
3 400 ± 125 <100 0.04 327 ± 10
A
IV 1 650 ± 150 550 ± 225 0.04 327 ± 10
A
2 >800 . . . 0.04 327 ± 10
A
3 580 ± 80 200 ± 75 0.04 327 ± 10
V . . . 635 ± 100 500 ± 250 0.04 327 ± 10 327 ± 10
A
VI . . . 650 ± 150 800 ± 250 0.04 327 ± 10
A
>5°C above the second melting peak temperature.
TABLE 2 Detail Requirements for Tests on Molded Specimens
Type Grade Thermal Instability Index, max Standard Specific Gravity Tensile Strength, min Elongation at break min %
min max MPa psi
I 1 50 2.13 2.18 13.8 2000 140
2 50 2.13 2.18 17.2 2500 200
II . . . 50 2.13 2.19 27.6 4000 300
III 1 50 2.14 2.22 28.0 4060 450
2 50 2.14 2.18 20.7 3000 300
3 50 2.14 2.18 28.0 4000 300
IV 1 50 2.13 2.19 25.5 3700 275
2 50 2.13 2.19 27.6 4000 300
3 50 2.15 2.18 27.6 4000 200
A A A A A A
V . . . NA NA NA NA NA NA
B A A A A A A
VI . . . NA NA NA NA NA NA
A
NA: Not Applicable by molding techniques included in this specification.
B
Extrusions of this resin show different degrees of clarity from the others.
Number and Type. Separators are not needed between Type, Grade, and Class. Provision for Special Notes is included so that other
information will be provided when required. An example would be in Specification D3295 where dimensions and tolerances are
specified for each AWG size within Type and Class. When Special Notes are used, they shall be preceded by a comma.
5. Mechanical Properties
5.1 The resins covered by this specification shall conform to the requirements prescribed in Tables 1 and 2 when tested by the
procedures specified herein. Table 1 lists tests to be carried out on resins. Table 2 lists tests requiring specimens molded as
described in Section 9.
6. Other Requirements
6.1 The resin shall be uniform and shall contain no additives or foreign material.
6.2 The color of the material as shipped by the seller shall be white.
7. Sampling
7.1 Sampling shall be statistically adequate to satisfy the requirements of 11.4
8. Number of Tests
8.1 Lot inspection shall include tests for bulk density, particle size and standard specific gravity. Periodic tests shall consist of
all the tests specified in Tables 1 and 2 and shall be made at least one per year.
8.2 The tests listed in Tables 1 and 2, as they apply, are sufficient to establish conformity of a material to this specification. One
set of tests specimens as prescribed in Section 7 shall be considered sufficient for testing each sample. The average of the results
for the specimens tested shall conform to the requirements of this specification.
9. Specimen Preparation
9.1 Test Disks:
See the Form and Style for ASTM Standards manual available from ASTM Headquarters.
D4894 − 19
FIG. 1 Assembly and Details of Die for Molding Test Specimens
9.1.1 Use the die shown in Fig. 1 for the molding of test disks. The test resin shall be near ambient temperature prior to molding
(Note 5). Warning—PTFE can evolve small quantities of gaseous products when heated above 204°C (400°F). Some of these
gases are harmful. Consequently, exhaust ventilation must be used whenever the resins are heated above this temperature, as they
are during the sintering operations that are a part of this specification. Since the temperature of burning tobacco exceeds 204°C
(400°F), those working with PTFE resins should ensure that tobacco is not contaminated.
9.1.2 Screen 14.5 g (for tensile properties) or 7.25 g (for electrical properties discussed in Appendix X1.7) of PTFE resin
through a No. 10 hand sieve into the die. Adjust the lower plug height to allow the resin in the die can be leveled by drawing a
straightedge in contact with the top of the die across the top of the die cavity. Insert the die in a suitable hydraulic press and apply
pressure gradually (Note 3) until a total of 34.5 MPa (5000 psi) is attained. Hold this pressure for 3 min. Remove the disk
identification on the disk at this time.
NOTE 3—As a guide, increasing the pressure at a rate of 3.45 MPa (500 psi)/min is suggested until the desired maximum pressure is attained.
9.1.3 Sinter the preforms in accordance with Table 3 (Note 4).
9.1.3.1 Use Procedure B for Types I, II and IV and Procedure C for Type III.
NOTE 4—Although the rate of heating application is not critical, the cooling cycle is most important and the conditions cited in these procedures must
be followed very closely. If they are not followed, the crystallinity of the disks and the resulting physical properties will be markedly changed. Therefore,
the use of a programmed oven is recommended for the most precise sintering cycle control so that the hood window will be left down during the entire
sintering procedure, the latter being an important safety consideration.
9.2 Test Specimens for Standard Specific Gravity (SSG) and Extended Specific Gravity (ESG):
9.2.1 A cylindrical preforming die, 28.6 mm (1 ⁄8 in.) internal diameter by at least 76.2 mm (3 in.) deep, is used to prepare the
preforms. End plug clearances shall be sufficient to ensure escape of air during pressing. The test resin shall be near ambient
temperature prior to molding (Note 5).
NOTE 5—For maximum precision, the weighing and preforming operations shall be carried out at 23 6 2°C (73.4 6 3.6°F) (the “near ambient”
temperature referred to herein). These operations shall not be preformed at temperatures below 21°C (70°F) due to the crystalline transition that occurs
in PTFE in this temperature region which leads to possible cracks in sintered specimens and differences in specimen density (as well as changes in other
physical properties). Problems caused by the effects of temperature on the specific gravity or density of PTFE will be minimized when the measurement
is made using immersion procedures if a sensitive thermometer (for example, one reading 60.1°C) is used in the liquid and the temperature is adjusted
to be at least 22°C.
9.2.2 Weigh out 12.0 6 0.1 g of resin and place it in the die. Screen non-free-flowing resins through a No. 10 sieve. Break up
compacted resins by hand-shaking cold resin in a half-filled sealed glass container. Condition the resin in the sealed glass container
in a freezer or dry-ice chest. After breaking up resin lumps, allow the sealed container to equilibrate to near ambient temperature.
Then screen and weigh the 12.0 6 0.1-g sample. Insert the die in a suitable hydraulic press and apply pressure gradually (Note
3) until a pressure of 34.5 MPa (5000 psi) is attained. Hold this pressure for 2 min. Remove the preform from the die. Write the
sample identification number using an appropriate marker that will not effect the PTFE during sintering on the preform at this time.
9.2.3 Sinter the preforms in accordance with Table 3 (Note 4).
9.2.3.1 For SSG specimens use Procedure B for Types I, II and IV and Procedure C for Type III.
9.2.3.2 For ESG specimens use Procedure F for Types I, II and IV and Procedure G for Type III.
D4894 − 19
TABLE 3 Sintering Procedures
B C D E F G H I
Initial temperature, °C (°F) 290 (554) 290 (554) 238 (460) 238 (460) 290 (554) 238 (460) 238 (460) 238 (460)
Rate of heating, °C/h (°F/h) 120 ± 10 120 ± 10 60 ± 5 60 ± 5 120 ± 10 60 ± 5 60 ± 5 60 ± 5
(216 ± 18) (216 ± 18) (108 ± 9) (108 ± 9) (216 ± 18) (108 ± 9) (108 ± 9) (108 ± 9)
Hold temperature, °C (°F) 380 ± 6 357 ± 8 371 ± 6 360 ± 6 380 ± 6 357 ± 8 380 ± 6 371 ± 6
(716 ± 10) (675 ± 15) (700 ± 10) (685 ± 10) (716 ± 10) (675 ± 5) (716 ± 10) (700 ± 10)
Hold time, min 30 + 2, −0 30 + 2, −0 240 ± 15 240 ± 15 360 ± 5 240 ± 15 960 ± 15 120 ± 5
Cooling rate, °C/h (°F/h) 60 ± 5 60 ± 5 60 ± 5 60 ± 5 60 ± 5 60 ± 5 60 ± 5 60 ± 5
(108 ± 9) (108 ± 9) (108 ± 9) (108 ± 9) (108 ± 9) (108 ± 9) (108 ± 9) (108 ± 9)
Final or second hold temperature, °C (°F) 294 ± 6 294 ± 6 238 ± 6 238 ± 6 294 ± 6 238 ± 6 238 ± 6 238 ± 6
(561 ± 10) (561 ± 10) (460 ± 10) (460 ± 10) (561 ± 10) (460 ± 10) (460 ± 10) (460 ± 10)
A A A A A
Second hold time, min 24 + 0.5, −0 24 + 0.5, −0 NA NA 24 + 0.5, −0 NA NA NA
1 1 1
Period to room temperature, min, h ⁄2 ⁄2 6 6 ⁄2 6 6 6
A
NA, Not applicable.
NOTE 6—Improved precision in SSG and ESG test results has been obtained with the use of an upright, cylindrical oven and an aluminum sintering
rack. The cylindrical oven has an inside diameter of 140 mm (5.5 in.) and an inside depth of 203 mm (8 in.) plus additional depth to accommodate a
50.8-mm (2-in.) thick cover, and is equipped with suitable heaters and controllers to sinter specimens in accordance with the Procedures in Table 3. The
rack, as shown in Fig. 2, allows preforms to be placed symmetrically in the center region of the oven. Place six preforms on each of the middle oven
rack shelves (if six or fewer preforms are to be sintered, place them on the middle rack, filling in with “dummies” as needed). Place “dummies” on the
top and bottom shelves. Specimens must be spaced evenly in a circle on each shelf, with none of them touching. An oven load must be no less than 18
pieces including “dummies.” “Dummies” are defined as normal 12-g specimens that have previously been through the sintering cycle. “Dummies” must
only be used for an additional two or three thermal cycles, due to eventual loss of thermal stability and physical form.
9.2.4 Remove all flash from each specimen so that no air bubbles will cling to the edges when the specimen is immersed in the
solution for weighing during the standard specific gravity and thermal instability index tests. It is recommended for this section
and during testing that cotton gloves be worn while handling test specimens.
9.3 Test Billets:
9.3.1 Use test specimens cut or skived from billets may be used as alternatives to the test disks described in 9.1 and 9.2 for Types
I, II, III and IV resins.
9.3.2 Mold test billets in a mold similar to Fig. 3, having an inside diameter of 57 mm (2.25 in.) and of sufficient height to
contain the resin sample. Plug clearance shall be sufficient to ensure escape of air during pressing. A 254-mm (10-in.) mold cavity
fill depth will produce a billet approximately 76 mm (3 in.) long from a resin charge of 400 6 50 g. Vary the billet length in
accordance with the testing to be done. The test resin shall be near ambient temperature prior to molding (Note 4).
9.3.2.1 Adjust the lower plug position using a support ring to position the mold shell so that the resin level will not come within
13 mm (0.5 in.) of the top of the mold cavity. Add the resin to the mold, insert the top plug, and apply hand pressure. Remove
the support ring, and place the mold in a hydraulic press.
9.3.2.2 Apply an initial pressure of 3.45 MPa (500 psi) 610 % and hold for 1 to 2 min. Increase the pressure smoothly to the
final preforming pressure in 3 to 5 min. Do not allow the mold shell to contact either press platen at any time during this preforming
step. The final pressure attained, if not recommended by the manufacturer of the particular material, shall be 34.5 MPa (5000 psi)
for Type I and 17.2 MPa (2500 psi) for Types II, III and IV. Hold under maximum pressure for 2 to 5 min. Release the pressure
by gradually “cracking” the pressure release valve without an apparent movement of the press platens. Remove the top pusher and
force the preform vertically out of the mold shell using a continuous, smooth movement.
NOTE 7—Remove the mold in a careful smooth movement from the die to prevent cracking.
9.3.3 Sinter the preform in accordance with Table 3 (Note 4).
9.3.3.1 Use Procedure D for Types I, II and IV and Procedure E for Type III—except for ESG specimens.
9.3.3.2 For ESG specimens use Procedure H for Types I, II, and IV and Procedure I for Type III.
9.3.4 Divide the test billet into sections by making transverse cuts by machining, or by a suitable alternate procedure, in
accordance with Fig. 4. Use a saw for the rough cuts between Sections I and II and between sections III and IV, but Faces C and
D must be prepared by machining. Prepare five test specimens for the determination of tensile properties from 0.8-mm ( ⁄32-in.)
thick slices machined from Section II, Face C, and machine a slice of suitable thickness for standard specific gravity measurements
as described in 10.5. Care shall be taken to avoid wedge-shaped cuts. Use the remainder of Section II to prepare tape specimens
by skiving 0.13 mm (5 mils) thick. Discard the initial five revolutions of skived tape before taking the test sample. Use the tape
for the determination of tensile properties, as an alternative to machined disks. If electrical properties, discussed in the Appendix,
are to be determined on tape, Sections II and III must be left together in order that a tape of sufficient width is obtained to allow
the cutting of a 50.8-mm (2-in.) diameter electrical test specimen.
9.4 Conditioning Test Specimens:
9.4.1 For tests of tensile properties and all tests requiring the measurement of specific gravity condition the test specimens in
general accordance with Procedure A of Practice D618, with the following deviations therefrom: a) the aging period shall be a
D4894 − 19
FIG. 2 SSG Samples Sintering Rack
FIG. 3 Preforming of PTFE Test Billet
minimum of 4 h immediately prior to testing, b) the laboratory temperature shall be 23 6 2°C (73.4 6 3.6°F), and c) there shall
be no requirement respecting humidity. The other tests require no conditioning of the molded test specimens.
9.5 Test Conditions:
9.5.1 Tests shall be conducted at the standard laboratory temperature of 23 6 2°C (73.4 6 3.6°F). See Note 5 for additional
details. Since these resins do not absorb water, the maintenance of constant humidity during testing is not required.
10. Test Methods
10.1 Melting Characteristics by Thermal Analysis:
10.1.1 Significance and Use—Most of the PTFE resins that fall within the scope of this specification have never been melted
(the only exception is Type V resin). These resins have higher melting peak temperatures on initial melting than on second or
subsequent meltings. Since PTFE resins that have been melted prior to use behave differently from those that have not, the melting
characteristics of resins provide important distinctions among them. Melting peak temperatures (see Fig. 5) are used to make these
D4894 − 19
FIG. 4 Sectioned PTFE Test Billet
FIG. 5 Melting Characteristics by Thermal Analysis
distinctions, and determine conformance of a resin to the melting peak temperature requirements given in Table 1 of this
specification. A resin that has been melted is not compatible with this specification, except for Type V.
10.1.2 Apparatus—Use apparatus described in Test Method D4591.
10.1.3 Procedure:
10.1.3.1 Measure melting peak temperatures in accordance with the procedures given in Method D4591. An initial melting peak
temperature above the melting peak temperature obtained on the second and subsequent melting (defined as the second melting
peak temperature) indicates that the resin was not melted before the test. The second melting peak temperature occurs at about
327°C (621°F). Usually the difference between the initial and second melting peak temperatures is greater than 5°C (9°F), as seen
in Table 1. If peak temperatures are difficult to discern from the curves, that is, if the peaks are rounded rather than pointed, straight
lines shall be drawn tangent to the sides of the peak. Where these lines intersect beyond the peak shall be taken as the peak
temperature. Where more than one peak occurs during the initial melting test, the presence of any peak corresponding to the second
melting peak temperature indicates the presence of some previously melted material.
10.2 Bulk Density:
10.2.1 Significance and Use—Bulk density gives some indication of how a resin will perform during feeding of molding and
ram extrusion equipment. PTFE resins have a tendency to compact during shipment and storage, and even though the material is
broken up by screening or some other means, original “as produced” results are not guaranteed. Because of this tendency to pack
D4894 − 19
FIG. 6 Details of Funnel for Bulk Density Test
under small amounts of compression or shear, Test Method D1895 is not applicable to these resins. The procedure given in the
following paragraphs must be used to measure this property.
10.2.2 Apparatus:
10.2.2.1 Funnel—A funnel arrangement as shown in Fig. 6.
10.2.2.2 Feeder —A feeder with a No. 8 wire screen placed over approximately the top two-thirds of the trough. The funnel
shall be mounted permanently in the feeder outlet.
10.2.2.3 Controller
10.2.2.4 Volumetric Cup and Cup Stand (Fig. 7)—The volumetric cup shall be calibrated initially to 250 mL by filling it with
distilled water, placing a planar glass plate on top, drying the outside of the cup, and weighing. The net weight shall be 250 6 0.5
g. The top and bottom faces of the volumetric cup and the cup stand shall be machined plane and parallel.
10.2.2.5 Leveling Device—The leveler (Fig. 8) shall be affixed permanently to the table and adjusted so that the sawtooth edge
of the leveler blade passes within 0.8 mm ( ⁄32 in.) of the top of the volumetric cup.
10.2.2.6 Work Surface—The work surface for holding the volumetric cup and leveler shall be essentially free from vibration.
The feeder, therefore, must be mounted on an adjoining table or wall bracket.
10.2.2.7 Balance—The balance having an extended beam shall have a capacity of 500 g and a sensitivity of 0.1 g or equivalent.
10.2.3 Procedure:
10.2.3.1 Place the clean, dry volumetric cup on the extended beam of the balance and adjust the tare to zero. Select about 500
mL of the resin to be tested, place it on the feeder screen and vibrate all of the resin through the screen and back into the sample
container twice to break up any lumps. Put the cup in the cup stand and place the assembly such that the distance of free polymer
1 1
fall from the feeder outlet to the top rim of the cup shall be 38.1 6 3.2 mm (1 ⁄2 6 ⁄8 in.). Increased fall causes packing in the cup
and h
...