ASTM F2625-24

Standard Test Method for Measurement of Enthalpy of Fusion, Percent Crystallinity, and Melting Point of Ultra-High Molecular Weight Polyethylene by Means of Differential Scanning Calorimetry

SIGNIFICANCE AND USE
5.1 The crystallinity of UHMWPE will influence its mechanical properties, such as creep and stiffness. The reported crystallinity will depend on the integration range used to determine the heat of fusion, and the theoretical heat of fusion of 100 % crystalline polyethylene used to calculate the percent crystallinity in an unknown specimen. Differential scanning calorimetry is an effective means of accurately measuring both heat of fusion and melting temperature.  
5.2 This test method is useful for both process control and research.
SCOPE
1.1 This quantitative test method discusses the measurement of the heat of fusion and the melting point of ultra-high molecular weight polyethylene (UHMWPE), and the subsequent calculation of the percentage of crystallinity. The method uses a differential scanning calorimeter and can be performed in the laboratory or in the field.  
1.2 This test method can be used for UHMWPE in powder form, consolidated form, finished product, or a used product. It can also be used for irradiated or chemically crosslinked UHMWPE.  
1.3 This test method does not suggest a desired range of crystallinity or melting points for specific applications.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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: 14-Mar-2024
• ICS: 07.030 - Physics. Chemistry
• ICS: 17.200.10 - Heat. Calorimetry
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.15 - Material Test Methods

Relations

• Replaces: ASTM F2625-10(2016) - Standard Test Method for Measurement of Enthalpy of Fusion, Percent Crystallinity, and Melting Point of Ultra-High-Molecular Weight Polyethylene by Means of Differential Scanning Calorimetry
• Effective Date: 15-Mar-2024
• Referred By: ASTM F2848-21 - Standard Specification for Medical-Grade Ultra-High-Molecular-Weight Polyethylene Yarns
• Effective Date: 15-Mar-2024
• Referred By: ASTM F2565-21 - Standard Guide for Extensively Irradiation-Crosslinked Ultra-High Molecular Weight Polyethylene Fabricated Forms for Surgical Implant Applications
• Effective Date: 15-Mar-2024
• Referred By: ASTM F2759-19 - Standard Guide for Assessment of the Ultra-High Molecular Weight Polyethylene (UHMWPE) Used in Orthopedic and Spinal Devices
• Effective Date: 15-Mar-2024

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: F2625 − 24
Standard Test Method for
Measurement of Enthalpy of Fusion, Percent Crystallinity,
and Melting Point of Ultra-High Molecular Weight
1
Polyethylene by Means of Differential Scanning Calorimetry
This standard is issued under the fixed designation F2625; 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 D3418 Test Method for Transition Temperatures and Enthal-
pies of Fusion and Crystallization of Polymers by Differ-
1.1 This quantitative test method discusses the measurement
ential Scanning Calorimetry
of the heat of fusion and the melting point of ultra-high
E177 Practice for Use of the Terms Precision and Bias in
molecular weight polyethylene (UHMWPE), and the subse-
ASTM Test Methods
quent calculation of the percentage of crystallinity. The method
E691 Practice for Conducting an Interlaboratory Study to
uses a differential scanning calorimeter and can be performed
Determine the Precision of a Test Method
in the laboratory or in the field.
E793 Test Method for Enthalpies of Fusion and Crystalliza-
1.2 This test method can be used for UHMWPE in powder
tion by Differential Scanning Calorimetry
form, consolidated form, finished product, or a used product. It
E967 Test Method for Temperature Calibration of Differen-
can also be used for irradiated or chemically crosslinked
tial Scanning Calorimeters and Differential Thermal Ana-
UHMWPE.
lyzers
1.3 This test method does not suggest a desired range of E968 Practice for Heat Flow Calibration of Differential
3
Scanning Calorimeters (Withdrawn 2023)
crystallinity or melting points for specific applications.
E1953 Practice for Description of Thermal Analysis and
1.4 The values stated in SI units are to be regarded as
Rheology Apparatus
standard. No other units of measurement are included in this
standard.
3. Terminology
1.5 This standard does not purport to address all of the
3.1 Symbols:
safety concerns, if any, associated with its use. It is the
3.1.1 ΔH , n—theoretical heat of fusion of 100 % crystalline
responsibility of the user of this standard to establish appro-
f
material (J/g).
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.1.2 ΔH , n—mass normalized heat of fusion of the test
s
1.6 This international standard was developed in accor-
sample (J/g).
dance with internationally recognized principles on standard-
3.1.3 T , n—melting temperature at the peak of the melting
p
ization established in the Decision on Principles for the
endotherm (°C).
Development of International Standards, Guides and Recom-
3.1.4 T , n—onset temperature of the melting endotherm
mendations issued by the World Trade Organization Technical
o
(°C).
Barriers to Trade (TBT) Committee.
3.1.5 %X, n—percentage of crystallinity of material.
2. Referenced Documents
2
2.1 ASTM Standards:
4. Summary of Test Method
4.1 This test method consists of placing a known mass of
1
UHMWPE in a sample pan and heating the sample pan at a
This test method is under the jurisdiction of ASTM Committee F04 on Medical
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
controlled temperature while measuring the heat flow to the
F04.15 on Material Test Methods.
sample pan and an empty reference pan. The area under the
Current edition approved March 15, 2024. Published April 2024. Originally
melting endotherm, indicative of the enthalpy of melting, is
approved in 2007. Last previous edition approved in 2016 as F2625 – 10 (2016).
DOI: 10.1520/F2625-24.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
F2625 − 24
NOTE 2—“Test location” is defined as the location on the sample where
normalized with the sample mass. This value is then normal-
the DSC analysis is performed.
ized with the theoretical enthalpy of melting of 100 % crystal-
line polyethylene to determine the percentage of crystallinity in
9. Preparation of Apparatus
the test sample.
9.1 The DSC test chamber sh
...

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: F2625 − 10 (Reapproved 2016) F2625 − 24
Standard Test Method for
Measurement of Enthalpy of Fusion, Percent Crystallinity,
and Melting Point of Ultra-High-Molecular Ultra-High
Molecular Weight Polyethylene by Means of Differential
1
Scanning Calorimetry
This standard is issued under the fixed designation F2625; 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 quantitative test method discusses the measurement of the heat of fusion and the melting point of ultra-high-molecular
ultra-high molecular weight polyethylene (UHMWPE), and the subsequent calculation of the percentage of crystallinity. The
method uses a differential scanning calorimeter and can be performed in the laboratory or in the field.
1.2 This test method can be used for UHMWPE in powder form, consolidated form, finished product, or a used product. It can
also be used for irradiated or chemically-crosslinked chemically crosslinked UHMWPE.
1.3 This test method does not suggest a desired range of crystallinity or melting points for specific applications.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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.
1.6 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
2.1 ASTM Standards:
D3418 Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential
Scanning Calorimetry
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E793 Test Method for Enthalpies of Fusion and Crystallization by Differential Scanning Calorimetry
E967 Test Method for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers
1
This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.15 on Material Test Methods.
Current edition approved April 1, 2016March 15, 2024. Published May 2016April 2024. Originally approved in 2007. Last previous edition approved in 20102016 as
F2625 – 10.F2625 – 10 (2016). DOI: 10.1520/F2625-10R16. 10.1520/F2625-24.
2
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
F2625 − 24
3
E968 Practice for Heat Flow Calibration of Differential Scanning Calorimeters (Withdrawn 2023)
E1953 Practice for Description of Thermal Analysis and Rheology Apparatus
3. Terminology
3.1 Symbols:
3.1.1 ΔH , n—theoretical heat of fusion of 100 % crystalline material (J/g).
f
3.1.2 ΔH , n—mass normalized heat of fusion of the test sample (J/g).
s
3.1.3 T , n—melting temperature at the peak of the melting endotherm (°C).
p
3.1.4 T , n—onset temperature of the melting endotherm (°C).
o
3.1.5 %X, n—percentage of crystallinity of material.
4. Summary of Test Method
4.1 This test method consists of placing a known mass of UHMWPE in a sample pan and heating the sample pan at a controlled
temperature while measuring the heat flow to the sample pan and an empty reference pan. The area under the melting endotherm,
indicative of the enthalpy of melting, is normalized with the sample mass. This value is then normalized with the theoretical
enthalpy of melting of 100 % crystalline polyethylene to determine the percentage of crystallinity in the test sam
...