ASTM D4745-19

Standard Classification System and Basis for Specification for Filled Polytetrafluoroethlyene (PTFE) Molding and Extrusion Materials Using ASTM Methods

ABSTRACT
This specification covers polytetrafluoroethylene(PTFE) filled molding compounds made with virgin PTFE resins defined in a certain specification except Types I, IV, V, and VI. PTFE compounds are classified into two types which are Type I as the nonpelletized material use for general purpose compression molding and Type II as the pelletized or free-flowing material use for molding, automatic molding or ram extrusion. Each type is further classified into thirteen grades distinguished by the nature of the filler. Different tests shall be conducted in order to determine the following properties: filler content, bulk density, specific gravity, and tensile properties.
SCOPE
1.1 This standard classification system and basis for specification covers polytetrafluoroethylene (PTFE) filled molding compounds made with virgin PTFE resins defined in Specification D4894, as Types II and III.
Note 1: This system can be used as a model for other PTFE compounds having particulate fillers that can survive the sintering temperatures of PTFE as can those listed in this standard. This system is restricted to virgin PTFE base resin for technical reasons. Recycled or reprocessed material cannot be processed successfully.
Note 2: The properties measured on commercially fabricated parts may differ from the listed values for samples prepared by the procedures given in this specification, depending on part geometry and processing parameters. Compounds used for ram extrusion are made from resins that comply with ASTM-D4745 Type II prior to their pre-sintering process. Property values measured on extruded products will vary from the listed values for Type II compounds which are prepared by the procedures given below which standardize mold diameter and sintering cycle. End users should assess these expected variations in ram extruded products to ensure their suitable use in their specific application.  
1.2 The values stated in SI units are to be regarded as standard.  
1.3 The following statement applies to the test method portion, Section 11, 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. See Note 5 for a specific warning statement.
Note 3: There is no known ISO equivalent to this standard.  
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.

General Information

• Status: Published
• Publication Date: 30-Apr-2019
• ICS: 83.140.99 - Other rubber and plastics products
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.15 - Thermoplastic Materials

Relations

• Replaces: ASTM D4745-14 - Standard Classification System and Basis for Specification
 for Filled Polytetrafluoroethlyene (PTFE) Molding and Extrusion Materials Using ASTM Methods
• Effective Date: 01-May-2019
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D1708-18 - Standard Test Method for Tensile Properties of Plastics by Use of Microtensile Specimens
• Effective Date: 01-Oct-2018
• Refers: ASTM D1600-18 - Standard Terminology for Abbreviated Terms Relating to Plastics (Withdrawn 2024)
• Effective Date: 01-Jan-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM D3892-15 - Standard Practice for Packaging/Packing of Plastics
• Effective Date: 01-Sep-2015
• Refers: ASTM D4894-15 - Standard Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusion Materials
• Effective Date: 01-May-2015
• Refers: ASTM D1600-14 - Standard Terminology for Abbreviated Terms Relating to Plastics
• Effective Date: 01-Feb-2014

Overview

ASTM D4745-19 is the standard classification system and basis for specification for filled polytetrafluoroethylene (PTFE) molding and extrusion materials using ASTM test methods. Issued by ASTM International, this standard applies to PTFE filled compounds manufactured with virgin PTFE resins, specifically types defined in ASTM D4894, Types II and III. The classification covers both general purpose compression molding materials and free-flowing materials suitable for automatic molding or ram extrusion.

This standard provides a comprehensive framework for classifying and specifying PTFE compounds containing various particulate fillers, ensuring reliable performance in applications requiring high chemical resistance and stability. The standard further outlines essential testing procedures and criteria for properties such as filler content, bulk density, specific gravity, and tensile strength, supporting quality assurance across the supply chain.

Key Topics

• Material Types:

  • Type I – Standard flow, nonpelletized PTFE materials designed for general-purpose compression molding.
  • Type II – Free-flow, pelletized PTFE materials suitable for compression or automatic molding and ram extrusion.

• Grades: Thirteen distinct grades are specified based on filler type, including glass fiber, graphite, carbon, bronze, molybdenum disulfide (MoS₂), and stainless steel, enabling tailored performance characteristics.

• Property Requirements:

  • Filler content: Rigorously determined to meet precision standards.
  • Bulk density: Evaluated under controlled test methods.
  • Specific gravity: Ensures uniformity and reliability of finished products.
  • Tensile properties: Tensile strength and elongation at break are determined by standardized microtensile testing.

• Testing Methods: The standard references established ASTM procedures for each test, ensuring consistency and comparability.

• Quality Control: Offers guidelines for statistical sampling, lot inspection, and material certification, ensuring reliable conformity with requirements.

Applications

ASTM D4745-19 is widely used in industries demanding highly reliable PTFE components with specific mechanical, chemical, and physical properties. Typical practical uses include:

• Manufacturing: Selection and specification of PTFE compounds for compression molding, automatic molding, and extrusion processes.
• Industrial Equipment: Fabrication of sealing, bearing, and insulating components requiring low friction and high chemical resistance.
• Quality Assurance: Establishment of consistent material specifications and acceptance criteria for suppliers and end users.
• Product Certification: Verification of bulk density, tensile strength, and elongation properties for certifying conformity to application requirements.

End users should account for potential variations in properties due to processing conditions or geometry, especially in ram-extruded products.

Related Standards

ASTM D4745-19 is supported by and references several other ASTM standards relevant to thermoplastic materials and testing, including:

• ASTM D4894: Specification for PTFE granular molding and ram extrusion materials.
• ASTM D792: Test methods for density and specific gravity of plastics by displacement.
• ASTM D1708: Test method for tensile properties of plastics using microtensile specimens.
• ASTM D3892: Practice for packaging and packing of plastics.
• ASTM D883 and D1600: Terminology standards for plastics and abbreviations.
• IEEE/ASTM SI-10: Standard for use of the International System of Units (SI).

Note: There is no known ISO equivalent to ASTM D4745-19, making it a key reference for PTFE compound classification and specification in international trade and manufacturing.

Practical Value

By following ASTM D4745-19, manufacturers, suppliers, and end users can:

• Ensure material compatibility with demanding processing conditions
• Achieve uniform quality and performance across PTFE compound applications
• Rely on internationally recognized test methods and property definitions
• Meet technical and regulatory requirements for critical components

Keywords: filled PTFE, polytetrafluoroethylene, PTFE compounds, fluoropolymers, molding materials, extrusion materials, ASTM standards, material testing.

Standards Content (Sample)

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.
Designation:D4745 −19
Standard Classification System and Basis for Specification for
Filled Polytetrafluoroethlyene (PTFE) Molding and Extrusion
Materials Using ASTM Methods
This standard is issued under the fixed designation D4745; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
1.1 This standard classification system and basis for speci- 2.1 ASTM Standards:
fication covers polytetrafluoroethylene (PTFE) filled molding D792Test Methods for Density and Specific Gravity (Rela-
compounds made with virgin PTFE resins defined in Specifi- tive Density) of Plastics by Displacement
cation D4894, as Types II and III. D883Terminology Relating to Plastics
D1600TerminologyforAbbreviatedTermsRelatingtoPlas-
NOTE 1—This system can be used as a model for other PTFE
tics
compounds having particulate fillers that can survive the sintering
D1708TestMethodforTensilePropertiesofPlasticsbyUse
temperatures of PTFE as can those listed in this standard. This system is
restricted to virgin PTFE base resin for technical reasons. Recycled or
of Microtensile Specimens
reprocessed material cannot be processed successfully.
D3892Practice for Packaging/Packing of Plastics
NOTE 2—The properties measured on commercially fabricated parts
D4894 Specification for Polytetrafluoroethylene (PTFE)
may differ from the listed values for samples prepared by the procedures
Granular Molding and Ram Extrusion Materials
given in this specification, depending on part geometry and processing
parameters. Compounds used for ram extrusion are made from resins that IEEE/ASTM SI-10Standard for Use of the International
comply with ASTM-D4745 Type II prior to their pre-sintering process.
System of Units (SI): The Modern Metric System
Property values measured on extruded products will vary from the listed
valuesforTypeIIcompoundswhicharepreparedbytheproceduresgiven
3. Terminology
below which standardize mold diameter and sintering cycle. End users
shouldassesstheseexpectedvariationsinramextrudedproductstoensure 3.1 Definitions—The terminology given in Terminology
their suitable use in their specific application.
D883 is applicable to this specification unless otherwise
specified.
1.2 The values stated in SI units are to be regarded as
standard.
3.2 Definitions of Terms Specific to This Standard:
1.3 The following statement applies to the test method
3.2.1 bulk density, n—the mass in kilograms per cubic liter
portion, Section 11, of this specification: This standard does of resin compound measured under the conditions of the test.
not purport to address all of the safety concerns, if any,
3.2.2 filled compound, n—blendofPTFEresinasthematrix
associated with its use. It is the responsibility of the user of this
and particulate fillers, generally glass, other inorganic,
standard to establish appropriate safety, health, and environ-
metallic, or polymeric materials that withstand the sintering
mental practices and determine the applicability of regulatory
temperature of PTFE (327 to 380°C).
limitations prior to use. See Note 5 for a specific warning
3.2.3 free-flow resins (pelletized), n—generally made by
statement.
treatment of finely divided resins to produce free-flowing
NOTE 3—There is no known ISO equivalent to this standard.
agglomerates.
1.4 This international standard was developed in accor-
3.2.4 lot, n—one production run.
dance with internationally recognized principles on standard-
3.2.5 pigmented compound, n—a compound in which a
ization established in the Decision on Principles for the
pigment is added for colorant purposes only.
Development of International Standards, Guides and Recom-
3.2.6 standard flow resins (nonpelletized), n—finely divided
mendations issued by the World Trade Organization Technical
resin with an average particle size less than 100 µm.
Barriers to Trade (TBT) Committee.
1 2
This specification is under the jurisdiction of ASTM Committee D20 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Materials. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2019. Published June 2019. Originally the ASTM website.
approved in 1991. Last previous edition approved in 2014 as D4745-14. DOI: Available from ASTM International Headquarters, 100 Barr Harbor Drive,
10.1520/D4745-19. West Conshohocken, PA 19428
*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
D4745−19
TABLE 1 PTFE Compounds, Type I, Standard Flow (Nonpelletized)
Molded Parts (Molded and Sintered)
Raw Resin
Specific Gravity, Specific Gravity,
Grade Bulk Density, Tensile Strength
Elongation at
min max
min, g/L
Break, min, %
min, MPa min, psi
1 15 % glass fiber 400 2.150 2.250 19.6 2840 220
2 25 % glass fiber 425 2.150 2.250 15.7 2270 180
3 35 % glass fiber 350 2.200 2.300 10.3 1500 150
4 5 % glass fiber and 5 % MoS 300 2.150 2.300 13.8 2000 200
5 15 % glass fiber and 5 % MoS 375 2.150 2.300 13.8 2000 150
6 10 % graphite 350 2.100 2.220 17.9 2600 120
7 15 % graphite 300 2.100 2.200 13.8 2000 100
8 25 % carbon and graphite 350 1.950 2.150 9.6 1400 20
9 32 % carbon and graphite 250 1.900 2.100 6.9 1000 20
10 40 % bronze 500 2.950 3.350 16.5 2400 100
11 60 % bronze 650 3.850 4.154 12.4 1800 50
12 55 % bronze and 5 % MoS 700 3.500 4.000 10.3 1500 80
13 50 % stainless steel 500 3.200 3.600 15.2 2200 120
0 As specified by customer and As specified by customer and supplier.
supplier
3.3 Abbreviations—Abbreviations are in accordance with 6. Requirements
Terminology D1600. PTFE is the abbreviated term for poly-
6.1 The PTFE compounds covered by this specification
tetrafluoroethylene.
shall be uniform (filler and resin particles evenly distributed)
and shall contain no foreign material.
4. Classification
6.2 The PTFE compounds shall conform to the require-
4.1 This specification covers the following two types of
ments prescribed in Tables 1-3 when tested by the procedures
PTFE compounds:
specifiedherein.Table1andTable3listrequirementsforType
4.1.1 Type I—Standard flow resins (nonpelletized) material,
I. Table 2 and Table 3 reference requirements for Type II.
for general-purpose compression molding.
4.1.2 Type II—Free-flow resins (pelletized) material, for
6.3 PTFE compounds containing high temperature polymer
compression molding, automatic molding, or ram extrusion.
fillers have the potential to be varicolored or mottled in
appearance. This appearance has no effect on physical proper-
4.2 Grades of each type distinguished by the nature of the
ties and shall not be cause for rejection.
filler(s) are listed in Tables 1-3.
4.3 A one-line system is used to specify materials covered
7. Sampling
by this specification. The system uses predefined cells to refer
7.1 Sampling shall be statistically adequate to satisfy the
to specific aspects of this specification, as the following
requirements of 12.4.
illustrates:
8. Number of Tests
Specification
Standard Number : Type : Grade : Class : Special
8.1 Routinelotinspectiontestsshallconsistofthosecarried
Block : : : : Notes
:: : : : out to determine the requirements specified in Tables 1-3
Example: Specification II 2
depending on type.
D4745 – 08
8.2 The requirements specified in Tables 1-3, as they apply,
4.3.1 For this example, the line callout would be Specifica-
are sufficient to establish conformity of a material to this
tion D4745–11, Type II, Grade 2, and would specify a
specification. When the number of test specimens is not stated
free-flowing (pelletized) composition of polytetrafluoroethyl-
inthetestmethod,singledeterminationsmaybemade.Ifmore
ene that has all of the properties listed for that type, and grade
than single determinations are made on specimens from
in the appropriate specified properties, tables, or both, in the
separate portions of the same sample, the results shall be
specification identified. A comma is used as the separator
averaged. The single or average result shall conform to the
between the standard number and the type. Separators are not
4 requirements prescribed in this specification.
needed between the type, grade, and class. A provision for
special notes is included so that other information can be
9. Test Specimens
provided when required. Precede special notes, when used, by
9.1 Test specimens shall be cut from a billet molded in
a comma.
accordance with the following procedure.
5. Ordering Information
9.1.1 Safety Warning—At normal processing temperatures,
PTFEliberatesharmfulvapors.Provideadequateventilationin
5.1 The filled compounds of PTFE are ordered using the
areas where PTFE compounds are exposed to elevated tem-
type, (see 4.1) and the grade (see reference Tables 1 and 2), or
peratures. Avoid contaminating smoking materials with PTFE
they are ordered using the designation of the supplier.
compounds.
See the ASTM Form and Style Manual, available from ASTM Headquarters. 9.2 Test Preforms:
D4745−19
TABLE 2 PTFE Compounds, Type II, Free-Flow (Pelletized)
Molded Parts (Molded and Sintered)
Raw Resin
Specific Gravity, Specific Gravity,
Grade Bulk Density, Tensile Strength
Elongation at
min max
min, g/L
Break, min, %
min, MPa min, psi
1 15 % glass fiber 625 2.150 2.25 13.8 2000 200
2 25 % glass fiber 625 2.150 2.250 12.4 1800 150
3 35 % glass fiber 650 2.150 2.250 8.3 1200 100
4 5 % glass fiber and 5 % MoS 575 2.150 2.300 17.2 2500 170
5 15 % glass fiber and 5 % MoS 600 2.150 2.300 13.8 1800 120
6 10 % graphite 600 2.070 2.190 13.8 2000 150
7 15 % graphite 550 2.100 2.200 10.3 1500 60
8 25 % carbon and graphite 500 1.950 2.100 8.3 1200 20
9 32 % carbon and graphite 400 1.900 2.200 6.9 1000 20
10 40 % bronze 750 2.950 3.250 13.8 2000 85
11 60 % bronze 900 3.800 4.000 10.3 1500 20
12 55 % bronze and 5 % MoS 900 3.500 4.000 6.9 1000 20
13 50 % stainless steel 850 3.200 3.600 13.8 2000 100
0 As specified by customer and As specified by customer and supplier.
supplier
TABLE 3 Required Filler Content
Mass, % Tolerance, ±, %
10to31
2 4 to 25 2
3 26to60 3
4 61to75 5
9.2.1 Test Billet
9.2.1.1 Prior to molding, screen the material through a
2.0-mm hand sieve, if necessary.
9.2.1.2 Preform solid test billets in a mold (see Fig. 1)
having a cross-sectional area not greater than 25.8cm ≤
(4in. )andofsufficientheighttocontainthesample.Endplug
clearance shall be sufficient to ensure escape of entrapped air
duringpressing.Amoldlengthof305to380mm(12to15in.)
produces a billet approximately 50 to 75 m
...

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: D4745 − 14 D4745 − 19
Standard Classification System and Basis for Specification for
Filled Polytetrafluoroethlyene (PTFE) Molding and Extrusion
Materials Using ASTM Methods
This standard is issued under the fixed designation D4745; 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 standard classification system and basis for specification covers polytetrafluoroethylene (PTFE) filled molding
compounds made with virgin PTFE resins defined in Specification D4894, as Types II and III.
NOTE 1—This system can be used as a model for other PTFE compounds having particulate fillers that can survive the sintering temperatures of PTFE
as can those listed in this standard. This system is restricted to virgin PTFE base resin for technical reasons. Recycled or reprocessed material cannot be
processed successfully.
NOTE 2—The properties measured on commercially fabricated parts may differ from the listed values for samples prepared by the procedures given
in this specification, depending on part geometry and processing parameters. Compounds used for ram extrusion are made from resins that comply with
ASTM-D4745 Type II prior to their pre-sintering process. Property values measured on extruded products will vary from the listed values for Type II
compounds which are prepared by the procedures given below which standardize mold diameter and sintering cycle. End users should assess these
expected variations in ram extruded products to ensure their suitable use in their specific application.
1.2 The values stated in SI units are to be regarded as standard.
1.3 The following statement applies to the test method portion, Section 11, 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. See Note 5 for a specific warning statement.
NOTE 3—There is no known ISO equivalent to this standard.
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:
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D1600 Terminology for Abbreviated Terms Relating to Plastics
D1708 Test Method for Tensile Properties of Plastics by Use of Microtensile Specimens
D3892 Practice for Packaging/Packing of Plastics
D4894 Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusion Materials
IEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System
3. Terminology
3.1 Definitions—The terminology given in Terminology D883 is applicable to this specification unless otherwise specified.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bulk density, n—the mass in kilograms per cubic metreliter of resin compound measured under the conditions of the test.
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 Aug. 1, 2014May 1, 2019. Published September 2014June 2019. Originally approved in 1991. Last previous edition approved in 20122014 as
ε01
D4745 - 11aD4745 - 14. . DOI: 10.1520/D4745-14.10.1520/D4745-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from ASTM International Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 19428
*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
D4745 − 19
TABLE 1 TFEPTFE Compounds, Type I, Standard Flow (Nonpelletized)
Molded Parts (Molded and Sintered)
Raw Resin
Specific Gravity, Specific Gravity,
Elongation,
Grade Bulk Density, Tensile Strength
min max
Elongation at
min, g/L
Break, min, %
min, MPa min, psi
1 15 % glass fiber 400 2.150 2.250 19.6 2840 220
2 25 % glass fiber 425 2.150 2.250 15.7 2270 180
3 35 % glass fiber 350 2.200 2.300 10.3 1500 150
4 5 % glass fiber and 5 % MoS 300 2.150 2.300 13.8 2000 200
5 15 % glass fiber and 5 % MoS 375 2.150 2.300 13.8 2000 150
6 10 % graphite 350 2.100 2.220 17.9 2600 120
7 15 % graphite 300 2.100 2.200 13.8 2000 100
8 25 % carbon and graphite 350 1.950 2.150 9.6 1400 20
9 32 % carbon and graphite 250 1.900 2.100 6.9 1000 20
10 40 % bronze 500 2.950 3.350 16.5 2400 100
11 60 % bronze 650 3.850 4.154 12.4 1800 50
12 55 % bronze and 5 % MoS 700 3.500 4.000 10.3 1500 80
13 50 % stainless steel 500 3.200 3.600 15.2 2200 120
0 As specified by customer and As specified by customer and supplier.
supplier
3.2.2 filled compound, n—blend of PTFE resin as the matrix and particulate fillers, generally glass, other inorganic, metallic,
or polymeric materials that withstand the sintering temperature of PTFE (327 to 380°C).
3.2.3 free-flow resins (pelletized), n—generally made by treatment of finely divided resins to produce free-flowing agglomerates.
3.2.4 lot, n—one production run.
3.2.5 pigmented compound, n—a compound in which a pigment is added for colorant purposes only.
3.2.6 standard flow resins (nonpelletized), n—finely divided resin with an average particle size less than 100 μm.
3.3 Abbreviations—Abbreviations are in accordance with Terminology D1600. PTFE is the acronym abbreviated term for
polytetrafluoroethylene.
4. Classification
4.1 This specification covers the following two types of PTFE compounds:
4.1.1 Type I—Standard flow resins (nonpelletized) material, for general-purpose compression molding.
4.1.2 Type II—Free-flow resins (pelletized) material, for compression molding, automatic molding, or ram extrusion.
4.2 Grades of each type distinguished by the nature of the filler(s) are listed in Tables 1-3.
4.3 A one-line system is used to specify materials covered by this specification. The system uses predefined cells to refer to
specific aspects of this specification, as the following illustrates:
Specification
Standard Number : Type : Grade : Class : Special
Block : : : : Notes
: : : : :
Example: Specification II 2
D4745 – 08
4.3.1 For this example, the line callout would be Specification D4745 – 11, Type II, Grade 2, and would specify a free-flowing
(pelletized) composition of polytetrafluoroethylene that has all of the properties listed for that type, and grade in the appropriate
specified properties, tables, or both, in the specification identified. A comma is used as the separator between the standard number
and the type. Separators are not needed between the type, grade, and class. A provision for special notes is included so that other
information can be provided when required. Precede special notes, when used, by a comma.
5. Ordering Information
5.1 The filled compounds of PTFE are ordered using the type, (see 4.1) and the grade (see reference Tables 1 and 2), or they
are ordered using the designation of the supplier.
6. Requirements
6.1 The PTFE compounds covered by this specification shall be uniform (filler and resin particles evenly distributed) and shall
contain no foreign material.
See the ASTM Form and Style Manual, available from ASTM Headquarters.
D4745 − 19
TABLE 2 TFEPTFE Compounds, Type II, Free-Flow (Pelletized)
Molded Parts (Molded and Sintered)
Raw Resin
Specific Gravity, Specific Gravity,
Elongation,
Grade Bulk Density, Tensile Strength
min max
Elongation at
min, g/L
Break, min, %
min, MPa min, psi
1 15 % glass fiber 625 2.150 2.25 13.8 2000 200
2 25 % glass fiber 625 2.150 2.250 12.4 1800 150
3 35 % glass fiber 650 2.150 2.250 8.3 1200 100
4 5 % glass fiber and 5 % MoS 575 2.150 2.300 17.2 2500 170
5 15 % glass fiber and 5 % MoS 600 2.150 2.300 13.8 1800 120
6 10 % graphite 600 2.070 2.190 13.8 2000 150
7 15 % graphite 550 2.100 2.200 10.3 1500 60
8 25 % carbon and graphite 500 1.950 2.100 8.3 1200 20
9 32 % carbon and graphite 400 1.900 2.200 6.9 1000 20
10 40 % bronze 750 2.950 3.250 13.8 2000 85
11 60 % bronze 900 3.800 4.000 10.3 1500 20
12 55 % bronze and 5 % MoS 900 3.500 4.000 6.9 1000 20
13 50 % stainless steel 850 3.200 3.600 13.8 2000 100
0 As specified by customer and As specified by customer and supplier.
supplier
TABLE 3 Required Filler Content
Mass, % Tolerance, ±, %
1 0 to 3 1
2 4 to 25 2
3 26 to 60 3
4 61 to 75 5
6.2 The PTFE compounds shall conform to the requirements prescribed in Tables 1-3 when tested by the procedures specified
herein. Table 1 and Table 3 list requirements for Type I. Table 2 and Table 3 reference requirements for Type II.
6.3 PTFE compounds containing high temperature polymer fillers have the potential to be varicolored or mottled in appearance.
This appearance has no effect on physical properties and shall not be cause for rejection.
7. Sampling
7.1 Sampling shall be statistically adequate to satisfy the requirements of 12.4.
8. Number of Tests
8.1 Routine lot inspection tests shall consist of those carried out to determine the requirements specified in Tables 1-3 depending
on type.
8.2 The requirements specified in Tables 1-3, as they apply, are sufficient to establish conformity of a material to this
specification. When the number of test specimens is not stated in the test method, single determinations may be made. If more than
single determinations are made on specimens from separate portions of the same sample, the results shall be averaged. The single
or average result shall conform to the requirements prescribed in this specification.
9. Test Specimens
9.1 Test specimens shall be cut from a billet molded in accordance with the following procedure. An acceptable alternate
procedure for molding a test plaque is described in Specification D4894, subsection 9.1.1.
9.1.1 Safety Warning—At normal processing temperatures, PTFE liberates harmful vapors. Provide adequate ventilation in areas
where PTFE compounds are exposed to elevated temperatures. Avoid contaminating smoking materials with PTFE compounds.
9.2 Test Preforms:
9.2.1 Test Billet
9.2.1.1 Prior to molding, screen the material through a 2.0-mm hand sieve, if necessary.
2 2
9.2.1.2 Preform solid test billets in a mold (see Fig. 1) having a cross-sectional area not greater than 25.8 cm ≤ (4 in. ) and of
sufficient height to contain the sample. End plug clearance shall be sufficient to ensure escape of entrapped air during pressing.
A mold length of 305 to 380 mm (12 to 15 in.) produces a billet approximately 50 to 75 mm (2 to 3 in
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