ASTM D8501-23a

Standard Classification System for and Basis for Specification for Unfilled Poly(Ether Ketone Ketone) (PEKK) Materials for Molding, Extrusion, Composites, Powder Coating and Additive Manufacturing

SCOPE
1.1 This specification covers poly(ether ketone ketone) materials, commonly referred to as PEKK, which are suitable for molding, extrusion, composites, powder coating and additive manufacturing. Only materials in this Class 6-8 are covered by this specification. This classification system provides requirements for the use of regrind or reprocessed materials.  
1.2 This specification covers thermoplastic resin materials supplied in pellet as well as powder form.  
1.3 This specification applies only to PEKK copolymers, without any additional fillers or inorganic additives, alloys, or treatments for modification of attributes.  
1.4 This classification system and subsequent line callout (specification) are intended to provide means of calling out poly(ether ketone ketone) materials used in the fabrication of end items or parts.  
1.5 Poly(ether ketone ketone) (PEKK) is a member of the poly (aryl ether ketone) or PAEK polymer family. PEKK has a broad range of repeat unit combinations of Isophthaloyl and Terephthaloyl repeat units. This standard classifies the polymer options.  
1.6 The values stated in SI units, as detailed in IEEE/ASTM S-10, are to be regarded as the standard. The values given in parentheses are for information only.  
1.7 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.
Note 1: There is no known ISO equivalent to this standard.
Note 2: PEKK is a thermoplastic polymer. Testing conditions can affect the technical results. Specimens prepared by techniques different than prescribed in this specification can have properties that vary from the values specified.  
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.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 83.080.20 - Thermoplastic materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.15 - Thermoplastic Materials

Relations

• Replaces: ASTM D8501-23 - Standard Classification System for and Basis for Specification for Unfilled Poly(Ether Ketone Ketone) (PEKK) Materials for Molding, Extrusion, Composites, Powder Coating and Additive Manufacturing
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D1238-23a - Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer
• Effective Date: 15-Nov-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D1238-23 - Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer
• Effective Date: 01-Feb-2023
• Refers: ASTM D883-22 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2022
• Refers: ASTM D1600-18 - Standard Terminology for Abbreviated Terms Relating to Plastics (Withdrawn 2024)
• Effective Date: 01-Jan-2018

Overview

ASTM D8501-23a is the standard classification system and basis for specification of unfilled poly(ether ketone ketone) (PEKK) materials intended for molding, extrusion, composites, powder coating, and additive manufacturing. Developed by ASTM Committee D20 on Plastics, this standard provides a robust framework for designating PEKK thermoplastic resins based on their chemical composition, physical forms, and performance characteristics. PEKK, a high-performance member of the poly(aryl ether ketone) (PAEK) family, is recognized for its exceptional thermal, mechanical, and chemical resistance. ASTM D8501-23a ensures material consistency for finished parts and products, supporting industry requirements for compliance and traceability in various manufacturing processes.

Key Topics

Classification and Specification:

• Covers only unfilled PEKK copolymers, with no additional fillers, inorganic additives, or attribute-modifying treatments.
• Applies to Class 6-8 materials, differentiated by the ratio of terephthaloyl (T) and isophthaloyl (I) repeat units, which determine thermal and crystallization properties.
• Material supplied in pellet or powder form for diverse processing methods.
• Allows controlled use of up to 20% regrind or reprocessed material, provided requirements are met and reported.

Grades and Performance Criteria:

• Grades are classified by melt volume flow rate (MVR), guiding suitability for applications such as injection molding, extrusion, composites, powder coatings, and additive manufacturing.
• Outlines specific requirements for properties like melting endotherm, specific gravity, tensile modulus, elongation, impact resistance, oxygen index, flame rating, iron content, dielectric strength, and moisture content.

Designation System:

• Provides a consistent method for PEKK material designations, indicating the standard, polymer family, class, grade, and any special requirements, facilitating procurement and specification in supply chains.

Testing and Sampling:

• Specifies standardized test methods (e.g., ASTM D638, ISO 527-1 for tensile properties; D792/ISO 1183 for specific gravity; D1238/ISO 1133 for MVR).
• Requires precise sample preparation, conditioning, and drying protocols to ensure reproducibility and accuracy.

Applications

ASTM D8501-23a supports a wide range of industrial and technical applications where performance, reliability, and traceability of PEKK are crucial:

• Additive Manufacturing (3D Printing): Selection and specification of PEKK grades for consistent print quality and part performance in aerospace, medical, and automotive sectors.
• Injection and Compression Molding: Provides guidance for process conditions and PEKK selection to produce high-strength molded components with uniform quality.
• Extrusion: Enables identification of grades suitable for continuous profiles, pipes, and film production.
• Composites: Facilitates use of suitable PEKK matrices in high-performance fiber-reinforced composites for structural parts.
• Powder Coatings: Assures compatibility and consistency for coating processes, ensuring finished product performance.

Related Standards

ASTM D8501-23a references and aligns with several industry-respected standards to ensure harmonized testing and material characterization:

• ASTM D638: Test Method for Tensile Properties of Plastics
• ASTM D792: Test Methods for Density and Specific Gravity of Plastics
• ASTM D1238: Melt Flow Rate of Thermoplastics
• ASTM D2863: Oxygen Index of Plastics
• ASTM D4000: Classification System for Plastics
• UL94: Flammability Tests for Plastic Materials
• ISO 527-1: Tensile Properties (Plastics)
• ISO 1133: Melt Mass-Flow Rate of Thermoplastics
• ISO 1183: Density Measurement of Plastics
• IEC 60243-1: Electric Strength of Insulating Materials

This standard is indispensable for manufacturers, engineers, and procurement specialists involved with high-performance thermoplastics, providing a clear and verifiable system for specifying PEKK materials to meet demanding application requirements.

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: D8501 − 23a
Standard Classification System for and Basis for Specification
for
Unfilled Poly(Ether Ketone Ketone) (PEKK) Materials for
Molding, Extrusion, Composites, Powder Coating and
Additive Manufacturing
This standard is issued under the fixed designation D8501; 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.
NOTE 2—PEKK is a thermoplastic polymer. Testing conditions can
1. Scope*
affect the technical results. Specimens prepared by techniques different
1.1 This specification covers poly(ether ketone ketone)
than prescribed in this specification can have properties that vary from the
materials, commonly referred to as PEKK, which are suitable values specified.
for molding, extrusion, composites, powder coating and addi-
1.8 This international standard was developed in accor-
tive manufacturing. Only materials in this Class 6-8 are
dance with internationally recognized principles on standard-
covered by this specification. This classification system pro-
ization established in the Decision on Principles for the
vides requirements for the use of regrind or reprocessed
Development of International Standards, Guides and Recom-
materials.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.2 This specification covers thermoplastic resin materials
supplied in pellet as well as powder form.
2. Referenced Documents
1.3 This specification applies only to PEKK copolymers,
2.1 ASTM Standards:
without any additional fillers or inorganic additives, alloys, or
D150 Test Methods for AC Loss Characteristics and Permit-
treatments for modification of attributes.
tivity (Dielectric Constant) of Solid Electrical Insulation
1.4 This classification system and subsequent line callout
D257 Test Methods for DC Resistance or Conductance of
(specification) are intended to provide means of calling out
Insulating Materials
poly(ether ketone ketone) materials used in the fabrication of
D618 Practice for Conditioning Plastics for Testing
end items or parts.
D638 Test Method for Tensile Properties of Plastics
1.5 Poly(ether ketone ketone) (PEKK) is a member of the
D792 Test Methods for Density and Specific Gravity (Rela-
poly (aryl ether ketone) or PAEK polymer family. PEKK has a
tive Density) of Plastics by Displacement
broad range of repeat unit combinations of Isophthaloyl and
D883 Terminology Relating to Plastics
Terephthaloyl repeat units. This standard classifies the polymer
D1238 Test Method for Melt Flow Rates of Thermoplastics
options.
by Extrusion Plastometer
D1600 Terminology for Abbreviated Terms Relating to Plas-
1.6 The values stated in SI units, as detailed in IEEE/ASTM
tics
S-10, are to be regarded as the standard. The values given in
D2863 Test Method for Measuring the Minimum Oxygen
parentheses are for information only.
Concentration to Support Candle-Like Combustion of
1.7 This standard does not purport to address all of the
Plastics (Oxygen Index)
safety concerns, if any, associated with its use. It is the
D3418 Test Method for Transition Temperatures and Enthal-
responsibility of the user of this standard to establish appro-
pies of Fusion and Crystallization of Polymers by Differ-
priate safety, health, and environmental practices and deter-
ential Scanning Calorimetry
mine the applicability of regulatory limitations prior to use.
D3892 Practice for Packaging/Packing of Plastics
NOTE 1—There is no known ISO equivalent to this standard.
D4000 Classification System for Specifying Plastic Materi-
als
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-
als. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2023. Published November 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2015. Last previous edition approved in 2023 as D8501 – 23. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D8501-23A. 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
D8501 − 23a
D6247 Test Method for Determination of Elemental Content 3.2.4 regrind (plastic), n—a product or scrap such as sprues,
of Polyolefins by Wavelength Dispersive X-ray Fluores- runners, sheet, film, rod and melted strands that have been
cence Spectrometry reclaimed by shredding and granulating for use in-house.
D8371 Test Method for Trace Metal Content Analysis in
3.2.5 reprocessed plastic, n—thermoplastic prepared from
Carbon Black
usually melt processed scrap or reject parts by a plastics
2.2 Underwriters’ Laboratories Standards (UL):
processor, or from non-standard or non-uniform virgin mate-
UL94 Standard for Tests for Flammability of Plastic Mate-
rial.
rials
3.2.6 terephthaloyl repeat unit, n—refers to the chemical
2.3 ISO Standards:
structure where ketone linkages are located in the para posi-
ISO 179 ⁄1eU Determination of Charpy Impact Properties
tion. See Fig. 2.
ISO 527-1 Determination of tensile properties
ISO 1133 Determination of the Melt Mass-Flow Rate (MFR)
and Volume-Flow Rate (MVR) of Thermoplastics
ISO 1183 Methods for determining the density of non-
cellular plastics
2.4 International Electrochemical Commission (IEC):
IEC 60243-1 Electric strength of insulation materials
IEC 60205 Calculation of the effective parameters of mag-
netic piece parts
3. Terminology
3.1 Definitions of Terms—Except for the terms defined in
FIG. 2 Para-linkage within Backbone of Poly(ether ketone ketone)
(terephthaloyl repeat unit)
3.2, the terminology used in this classification system is in
accordance with Terminologies D883 and D1600.
3.2.7 viscosity, n—the property of resistance to flow in any
3.2 Definitions of Terms Specific to This Standard:
material with fluid properties.
3.2.1 copolymer, n—a polymer made by the reaction of two
or more different monomers with units of more than one kind.
4. Classification
3.2.2 isophthaloyl repeat unit, n—refers to the chemical
4.1 Poly(ether ketone ketone) PEKK materials shall be
structure where ketone linkages are located in the meta
classified into Classes that are subdivided into Grades as shown
position. See Fig. 1.
in Tables 1 and 2.
4.1.1 Class—PEKK polymers contain only two types of
repeat units and be classified only by the ratio of Terephthaloyl
(T) and Isophthaloyl (I) units, as described in Table 1. The
Table 1 ratios of repeat units can greatly affect the properties of
the polymer. Table 1 describes, also, the melting point ranges
for each class.
NOTE 3—The crystallinity and crystallization rate are strongly affected
by the structure of the polymer backbone linkages (para or meta).
4.1.1.1 Determine the T/I ratio by NMR analysis. Melt point
ranges indicated are representative of the T to I ratio for each
FIG. 1 Meta-linkage within Backbone of Poly(ether ketone ketone)
class.
(isophthaloyl repeat unit)
4.1.2 Grade—The desirable melt volume flow rate (MVR)
of PEKK polymers is a function of the requirements of the
3.2.3 poly(ether ketone ketone), n—a highly customizable
application or intended use. Thus, the desirable melt flow will
semicrystalline polymer in the poly(aryl ether ketone) (PAEK)
depend on whether the polymer is intended to be used as an
family, consisting of two polymer repeat units consisting of
injection molding grade, powder coating grade, 3D printing
either terephthaloyl or isophthaloyl repeat units.
grade or extrusion grade. The grades shall be distinguished as
3.2.3.1 Discussion—Poly(ether ketone ketone) specifically
has a repeating structural unit containing one ether and two
TABLE 1 Class Assignment Based on Ratio of (T) and (I)
ketone linkages.
A
Class Percent of (T) Melting Point
Range, °C
6 57-62 290-305
Available from Underwriters Laboratories (UL), UL Headquarters, 333 Pfing-
7 68-73 325-350
sten Road, Northbrook, IL, 60062, http://www.ul.com.
8 78-85 355-370
Available from International Organization for Standardization (ISO), ISO
A
Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
For some medium to very high viscosity materials, it’s possible that a melt point
Switzerland, https://www.iso.org.
will not be detected with a ramp rate of 20°C/min. Since different ramp rates can
Available from International Electrotechnical Commission (IEC), 3, rue de
influence the detection of transition temperatures, other rates can be used as long
Varembé, 1st floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, https://
as the rate is noted, and the DSC is calibrated at that ramp rate.
www.iec.ch.
D8501 − 23a
TABLE 2 Grade Designation Based on Melt Volume Flow Rate (MVR) for Unfilled PEKK Materials
MVR (cm /10min) Range Grade Description Applications
A
@ 380°C and 1 or 5 kg weight Based on Viscosity
60-120 Ultra Low Viscosity Intended for composites
16-60 Very Low Viscosity Intended for reinforced grades
8-16 Low Viscosity Intended for reinforced grades
4-8 Medium Viscosity Intended for extrusion or injection molding
11-24 High Viscosity Intended for extrusion
3-12 Very High Viscosity Intended for extrusion
A
1 kg weight for ultra low, very low, low and medium viscosity grades; 5 kg weight for high and very high viscosity grades.
TABLE 4 Examples of Designation or Specification Callout
low, medium or high volume flow rate and the ranges shall be
Standard Polymer Class Grade Special
as required by Table 2. The melt volume flow rate shall be
Block Family Notes
measured in accordance with ISO 1133 or Test Method D1238,
Specification PEKK 6 Low “.”
at a temperature of 380°C, by using a 5-kg weight (for the high
ASTM Viscosity
D8501
and very high viscosity grades) and a 1-kg weight for all the
Specification PEKK 8 High “High purity
other grades.
ASTM Viscosity product,
D8501 no use of
4.2 Tables 3 and 4 describe predefined cells to be used to
regrind”
refer to specific aspects of this specification.
Specification
Standard Number Block, Class, Grade, Additional Requirements
Example: ASTM D8501 PEKK Class 6, Grade Low Viscosity
other information, such as a preferred property range, can be provided
NOTE 4—Additional requirements could be ASTM D4000 suffixes or
when required.
special notes.
NOTE 5—Ranges for MVR are classification values only. 4.2.2 When additional requirements are used, they shall be
preceded by a comma. If a callout section is not used, it is
4.2.1 For the examples shown in Table 4, this line callout
acceptable to leave it out or to use three dashes to indicate that
would be ASTM D8501 PEKK Class 6, Grade Low Viscosity.
the section is not required.
This describes a PEKK polymer with 57-62 % Terephthaloyl
4.2.3 Suffıxes—When additional requirements are needed
(T) repeat unit and 38-43 % Isophthaloyl (I) repeat unit with a
that are not covered by the basic requirements or cell-table
melting point between 290-305°C, and a melt volume flow rate
3 3
requirements, indicate through the use of suffixes. A list of
of between 8 cm and 16 cm per 10 minutes when tested in
suffixes can be found in Classification System D4000 (Table 3)
accordance with ISO 1133 or Test Method D1238 at a 380°C
and are to be used for additional requirements as appropriate
temperature using a 1 kg weight. The second example shows a
callout for PEKK, D8501, Class 8, Grade High Viscosity, “high
NOTE 7—With the use of ASTM D4000 suffixes, the example of
purity product, no use of regrind”. This describes a PEKK “tensile strength at yield >= 130 MPa” would be replaced by the suffix
“KX130” (for ISO 527) or “KY130” (for ASTM D638).
polymer with 78-85 % Terephthaloyl (T) repeat unit and
15-22 % Isophthaloyl (I) repeat unit with a melting point of
4.2.4 An example callout for a PEKK polymer requiring
between 355 and 370°C, and a melt volume flow rate of
80 % terephthaloyl repeat unit, no specific viscosity, and a
between 3 and 12cm per 10 minutes when tested in accor-
tensile yield strength of at least 130 Mpa would be:
dance with ISO 1133 or Test Method D1238 at a 380°C
ASTM D8501 PEKK, Class 8, “minimum 130 Mpa tensile yield strength
temperature and using a 5 kg weight. A comma shall be used as required.”
the separator between the standard number, the class number
5. General Requirements
and the grade type. The cells addressing grade callout and
special notes are not mandatory. The special notes are encased
5.1 The material shall be free of foreign matter and of
in quotations.
uniform composition.
5.1.1 Use of regrind or reprocessed PEKK material is
NOTE 6—A provision for special notes is included in the table so that
permissible with up to a maximum of 20 % as long as it meets
specifications of the callout; however, this shall be reported in
TABLE 3 Classification for Unfilled PEKK Materials
the additional requirements cell.
Standard Polymer Class Grade
Number Family
6. Detail Requirements
Block
Example: PEKK 6, 7, 8 Ultra Low
6.1 General Attributes:
Specification Viscosity,
6.1.1 Peak Melting Endotherm Grade 8—The material cov-
ASTM D8501 Very low
viscosity,
ered by this specification shall have a peak melting endotherm
Low Viscosity,
not exceeding the limits for a Class 8 material, as required by
Medium
viscosity, Table 1 when tested in accordance with Test Method D3418.
High viscosity,
The determination of melting temperature in accordance with
Very High
6.1.1 involves heating, cooling and reheating a solid specimen
Viscosity
with a weight 5 mg to 10 mg, at a heating rate of 20°C/min,
D8501 − 23a
ranging from 20°C to 400°C, with no upper limit hold. The than 80 kV/mm (2032 kV/ in.) by the “short-time” method of
peak melting temperature during the reheat shall be recorded. Test Methods IEC 60243-1, using specimens that are 0.1-mm
6.1.2 Peak Melting Endotherm Grade 6 and 7—The deter- (0.004-in.) thick, as tested in air using 25.4-mm (1-in.) Type 3
mination of melting temperature in accordance with 6.1.1 for electrodes.
materials in Classes 6 and 7, as required by Table 1, shall also 6.3.3 Dielectric Constant—The materials covered by this
involve heating, cooling and reheating a solid specimen with a specification shall have a dielectric constant less than 3.5 at 1
weight o
...

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: D8501 − 23 D8501 − 23a
Standard Classification System for and Basis for Specification
for
Unfilled Poly(Ether Ketone Ketone) (PEKK) Materials for
Molding, Extrusion, Composites, Powder Coating and
Additive Manufacturing
This standard is issued under the fixed designation D8501; 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 Scope*
1.1 This specification covers poly(ether ketone ketone) materials, commonly referred to as PEKK, which are suitable for molding,
extrusion, composites, powder coating and additive manufacturing. Only materials in this Class 6-8 are covered by this
specification. This classification system provides requirements for the use of regrind or reprocessed materials.
1.2 This specification covers thermoplastic resin materials supplied in pellet as well as powder form.
1.3 This specification applies only to PEKK copolymers, without any additional fillers or inorganic additives, alloys, or treatments
for modification of attributes.
1.4 This classification system and subsequent line callout (specification) are intended to provide means of calling out poly(ether
ketone ketone) materials used in the fabrication of end items or parts.
1.5 Poly(ether ketone ketone) (PEKK) is a member of the poly (aryl ether ketone) or PAEK polymer family. PEKK has a broad
range of repeat unit combinations of Isophthaloyl and Terephthaloyl repeat units. This standard classifies the polymer options.
1.6 The values stated in SI units, as detailed in IEEE/ASTM S-10, are to be regarded as the standard. The values given in
parentheses are for information only.
1.7 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.
NOTE 1—There is no known ISO equivalent to this standard.
NOTE 2—PEKK is a thermoplastic polymer. Testing conditions can affect the technical results. Specimens prepared by techniques different than prescribed
in this specification can have properties that vary from the values specified.
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.
This test method 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, 2023Nov. 1, 2023. Published August 2023November 2023. Originally approved in 2015. Last previous edition approved in 2023 as
D8501 – 23. DOI: 10.1520/D8501-23.10.1520/D8501-23A.
*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
D8501 − 23a
2. Referenced Documents
2.1 ASTM Standards:
D150 Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation
D257 Test Methods for DC Resistance or Conductance of Insulating Materials
D618 Practice for Conditioning Plastics for Testing
D638 Test Method for Tensile Properties of Plastics
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D1238 Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer
D1600 Terminology for Abbreviated Terms Relating to Plastics
D2863 Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics
(Oxygen Index)
D3418 Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential
Scanning Calorimetry
D3892 Practice for Packaging/Packing of Plastics
D4000 Classification System for Specifying Plastic Materials
D6247 Test Method for Determination of Elemental Content of Polyolefins by Wavelength Dispersive X-ray Fluorescence
Spectrometry
D8371 Test Method for Trace Metal Content Analysis in Carbon Black
2.2 Underwriters’ Laboratories Standards (UL):
UL94 Standard for Tests for Flammability of Plastic Materials
2.3 ISO Standards:
ISO 179 ⁄1eU Determination of Charpy Impact Properties
ISO 527-1 Determination of tensile properties
ISO 1133 Determination of the Melt Mass-Flow Rate (MFR) and Volume-Flow Rate (MVR) of Thermoplastics
ISO 1183 Methods for determining the density of non-cellular plastics
2.4 International Electrochemical Commission (IEC):
IEC 60243-1 Electric strength of insulation materials
IEC 60205 Calculation of the effective parameters of magnetic piece parts
3. Terminology
3.1 Definitions of Terms—Except for the terms defined in 3.2, the terminology used in this classification system is in accordance
with Terminologies D883 and D1600.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 copolymer, n—a polymer made by the reaction of two or more different monomers with units of more than one kind.
3.2.2 isophthaloyl repeat unit, n—refers to the chemical structure where ketone linkages are located in the meta position. See Fig.
1.
3.2.3 poly(ether ketone ketone), n—a highly customizable semicrystalline polymer in the poly(aryl ether ketone) (PAEK) family,
consisting of two polymer repeat units consisting of either terephthaloyl or isophthaloyl repeat units.
3.2.3.1 Discussion—
Poly(ether ketone ketone) specifically has a repeating structural unit containing one ether and two ketone linkages.
3.2.4 regrind (plastic), n—a product or scrap such as sprues, runners, sheet, film, rod and melted strands that have been reclaimed
by shredding and granulating for use in-house.
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 Underwriters Laboratories (UL), UL Headquarters, 333 Pfingsten Road, Northbrook, IL, 60062, http://www.ul.com.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland,
https://www.iso.org.
Available from International Electrotechnical Commission (IEC), 3, rue de Varembé, 1st floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, https://www.iec.ch.
D8501 − 23a
FIG. 1 Meta-linkage within Backbone of Poly(ether ketone ketone) (isophthaloyl repeat unit)
3.2.5 reprocessed plastic, n—thermoplastic prepared from usually melt processed scrap or reject parts by a plastics processor, or
from non-standard or non-uniform virgin material.
3.2.6 terephthaloyl repeat unit, n—refers to the chemical structure where ketone linkages are located in the para position. See Fig.
2.
FIG. 2 Para-linkage within Backbone of Poly(ether ketone ketone) (terephthaloyl repeat unit)
3.2.7 viscosity, n—the property of resistance to flow in any material with fluid properties.
4. Classification
4.1 Poly(ether ketone ketone) PEKK materials shall be classified into Classes that are subdivided into Grades as shown in Tables
1 and 2.
4.1.1 Class—PEKK polymers contain only two types of repeat units and be classified only by the ratio of Terephthaloyl (T) and
Isophthaloyl (I) units, as described in Table 1. The Table 1 ratios of repeat units can greatly affect the properties of the polymer.
Table 1 describes, also, the melting point ranges for each class.
NOTE 3—The crystallinity and crystallization rate are strongly affected by the structure of the polymer backbone linkages (para or meta).
4.1.1.1 Determine the T/I ratio by NMR analysis. Melt point ranges indicated are representative of the T to I ratio for each class.
TABLE 1 Class Assignment Based on Ratio of (T) and (I)
A
Class Percent of (T) Melting Point
Range, °C
6 57-62 290-305
7 68-73 325-350
8 78-85 355-370
A
For some medium to very high viscosity materials, it’s possible that a melt point
will not be detected with a ramp rate of 20°C/min. Since different ramp rates can
influence the detection of transition temperatures, other rates can be used as long
as the rate is noted, and the DSC is calibrated at that ramp rate.
D8501 − 23a
TABLE 2 Grade Designation Based on Melt Volume Flow Rate (MVR) for Unfilled PEKK Materials
MVR (cm /10min) Range Grade Description Applications
A
@ 380°C and 1 or 5 kg weight Based on Viscosity
60-120 Ultra Low Viscosity Intended for composites
16-60 Very Low Viscosity Intended for reinforced grades
8-16 Low Viscosity Intended for reinforced grades
4-8 Medium Viscosity Intended for extrusion or injection molding
11-24 High Viscosity Intended for extrusion
3-12 Very High Viscosity Intended for extrusion
A
1 kg weight for ultra low, very low, low and medium viscosity grades; 5 kg weight for high and very high viscosity grades.
4.1.2 Grade—The desirable melt volume flow rate (MVR) of PEKK polymers is a function of the requirements of the application
or intended use. Thus, the desirable melt flow will depend on whether the polymer is intended to be used as an injection molding
grade, powder coating grade, 3D printing grade or extrusion grade. The grades shall be distinguished as low, medium or high
volume flow rate and the ranges shall be as required by Table 2. The melt volume flow rate shall be measured in accordance with
ISO 1133 or Test Method D1238, at a temperature of 380°C, by using a 5-kg weight (for the high and very high viscosity grades)
and a 1-kg weight for all the other grades.
4.2 Tables 3 and 4 describe predefined cells to be used to refer to specific aspects of this specification.
Specification
Standard Number Block, Class, Grade, Additional Requirements
Example: ASTM D8501 PEKK Class 6, Grade Low Viscosity
NOTE 4—Additional requirements could be ASTM D4000 suffixes or special notes.
NOTE 5—Ranges for MVR are classification values only.
4.2.1 For the examples shown in Table 4, this line callout would be ASTM D8501 PEKK Class 6, Grade Low Viscosity. This
describes a PEKK polymer with 57-62 % Terephthaloyl (T) repeat unit and 38-43 % Isophthaloyl (I) repeat unit with a melting
3 3
point between 290-305°C, and a melt volume flow rate of between 8 cm and 16 cm per 10 minutes when tested in accordance
with ISO 1133 or Test Method D1238 at a 380°C temperature using a 1 kg weight. The second example shows a callout for PEKK,
D8501, Class 8, Grade High Viscosity, “high purity product, no use of regrind”. This describes a PEKK polymer with 78-85 %
Terephthaloyl (T) repeat unit and 15-22 % Isophthaloyl (I) repeat unit with a melting point of between 355 and 370°C, and a melt
volume flow rate of between 3 and 12cm per 10 minutes when tested in accordance with ISO 1133 or Test Method D1238 at a
380°C temperature and using a 5 kg weight. A comma shall be used as the separator between the standard number, the class number
and the grade type. The cells addressing grade callout and special notes are not mandatory. The special notes are encased in
quotations.
NOTE 6—A provision for special notes is included in the table so that other information, such as a preferred property range, can be provided when required.
4.2.2 When additional requirements are used, they shall be preceded by a comma. If a callout section is not used, it is acceptable
to leave it out or to use three dashes to indicate that the section is not required.
TABLE 3 Classification for Unfilled PEKK Materials
Standard Polymer Class Grade
Number Family
Block
Example: PEKK 6, 7, 8 Ultra Low
Specification Viscosity,
ASTM D8501 Very low
viscosity,
Low Viscosity,
Medium
viscosity,
High viscosity,
Very High
Viscosity
D8501 − 23a
TABLE 4 Examples of Designation or Specification Callout
Standard Polymer Class Grade Special
Block Family Notes
Specification PEKK 6 Low “.”
ASTM Viscosity
D8501
Specification PEKK 8 High “High purity
ASTM Viscosity product,
D8501 no use of
regrind”
4.2.3 Suffıxes—When additional requirements are needed that are not covered by the basic requirements or cell-table requirements,
indicate through the use of suffixes. A list of suffixes can be found in Classification System D4000 (Table 3) and are to be used
for additional requirements as appropriate
NOTE 7—With the use of ASTM D4000 suffixes, the example of “tensile strength at yield >= 130 MPa” would be replaced by the suffix “KX130” (for
ISO 527) or “KY130” (for ASTM D638).
4.2.4 An example callout for a PEKK polymer requiring 80 % terephthaloyl repeat unit, no specific viscosity, and a tensile yield
strength of at least 130 Mpa would be:
ASTM D8501 PEKK, Class 8, “minimum 130 Mpa tensile yield strength required.”
5. General Requirements
5.1 The material shall be free of foreign matter and of uniform composition.
5.1.1 Use of regrind or reprocessed PEKK material is permissible with up to a maximum of 20 % as long as it meets specifications
of the callout; however, this shall be reported in the additional requirements cell.
6. Detail Requirements
6.1 General Attributes:
6.1.1 Peak Melting Endotherm Grade 8—The material covered by this specification shall have a peak melting endotherm not
exceeding the limits for a Class 8 material, as required by Table 1 when tested in accordance with Test Method D3418. The
determination of melting temperature in accordance with 6.1.1 involves heating, cooling and reheating a solid specimen with a
weight 5 mg to 10 mg, at a heating rate of 20°C/min, ranging from 20°C to 400°C, with no upper limit hold. The peak melting
temperature during the reheat shall be recorded.
6.1.2 Peak Melting Endotherm Grade 6 and 7—The determination of melting temperature in accordance with 6.1.1 for materials
in Classes 6 and 7, as required by Table 1, shall also involve heating, cooling and reheating a solid specimen with a weight of 5
mg to 10 mg at a heating rate of 20°C/min, ranging from 20°C to 380°C, with no upper limit hold. The peak temperature shall
be determined on the initial heating phase, by analyzing the highest melting endotherm.
6.1.3 Specific Gravity—A solid specimen of the material covered by this specification shall have the
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