ASTM F624-09(2015)e1

Standard Guide for Evaluation of Thermoplastic Polyurethane Solids and Solutions for Biomedical Applications

SIGNIFICANCE AND USE
4.1 This guide is intended to aid device fabricators in the selection of proper commercially available polyurethane solids and solutions for their application.  
4.2 The polyurethanes covered by this guide may be thermoformed or solution cast into biomedical devices for use as surgical aids or for implantation as determined to be appropriate, based on supporting biocompatibility and physical test data.
SCOPE
1.1 This guide covers the evaluation of thermoplastic polyurethanes in both solid and solution form for biomedical applications. The polymers have been reacted to completion and require no further chemical processing.  
1.2 The tests and methods listed in this guide may be referenced in specifications containing minimum required values and tolerances for specific end-use products.  
1.3 Standard tests for biocompatibility are included to aid in the assessment of safe utilization in biomedical applications. Compliance with these criteria shall not be construed as an endorsement of implantability. Since many compositions, formulations, and forms of thermoplastic polyurethanes in solid and solution forms are within this material class, the formulator or fabricator must evaluate the biocompatibility of the specific composition or form in the intended use and after completion of all manufacturing processes including sterilization.  
1.4 Purchase specifications may be prepared by agreement between the buyer and seller by selection of appropriate tests and methods from those listed applicable to the specific biomedical end use.  
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Published
• Publication Date: 28-Feb-2015
• ICS: 11.100.99 - Other standards related to laboratory medicine
• ICS: 83.080.20 - Thermoplastic materials
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.11 - Polymeric Materials

Relations

• Replaces: ASTM F624-09 - Standard Guide for Evaluation of Thermoplastic Polyurethane Solids and Solutions for Biomedical Applications
• Effective Date: 01-Mar-2015
• Refers: ASTM E96/E96M-24 - Standard Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
• Effective Date: 01-Mar-2024
• Refers: ASTM E96/E96M-23 - Standard Test Methods for Gravimetric Determination of Water Vapor Transmission Rate of Materials
• Effective Date: 15-Nov-2023
• Refers: ASTM D1238-23a - Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer
• Effective Date: 15-Nov-2023
• Refers: ASTM D149-20 - Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies
• Effective Date: 01-Jan-2020
• Refers: ASTM D790-17 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Jul-2017
• Refers: ASTM D2990-17 - Standard Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics
• Effective Date: 01-Mar-2017
• Refers: ASTM F748-16 - Standard Practice for Selecting Generic Biological Test Methods for Materials and Devices
• Effective Date: 01-Apr-2016
• Refers: ASTM D790-15 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Dec-2015
• Refers: ASTM D790-15e1 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
• Effective Date: 01-Dec-2015
• Refers: ASTM E96/E96M-15 - Standard Test Methods for Water Vapor Transmission of Materials
• Effective Date: 01-May-2015
• Refers: ASTM E96/E96M-14 - Standard Test Methods for Water Vapor Transmission of Materials
• Effective Date: 15-Oct-2014
• Refers: ASTM E96/E96M-13 - Standard Test Methods for Water Vapor Transmission of Materials
• Effective Date: 01-Nov-2013
• Refers: ASTM D1238-13 - Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer
• Effective Date: 01-Aug-2013
• Refers: ASTM E96/E96M-12 - Standard Test Methods for Water Vapor Transmission of Materials
• Effective Date: 15-Dec-2012

Overview

ASTM F624-09(2015)e1: Standard Guide for Evaluation of Thermoplastic Polyurethane Solids and Solutions for Biomedical Applications provides comprehensive guidance for evaluating thermoplastic polyurethanes (TPUs) in both solid and solution forms for biomedical device fabrication. The standard assists device manufacturers in the selection and assessment of commercially available polyurethanes, which can be thermoformed or solution-cast into medical devices, surgical aids, or implantable products, depending on supporting biocompatibility and physical test data.

This guide outlines recommended test methods, biocompatibility assessments, and application considerations to ensure that selected TPUs meet the safety and performance requirements of specific biomedical end uses. While providing a framework for evaluation, ASTM F624 does not replace application-specific testing or regulatory compliance obligations.

Keywords: thermoplastic polyurethane, biomedical applications, medical device materials, polyurethane evaluation, ASTM F624, biocompatibility, physical testing, device fabrication

Key Topics

• Material Evaluation: Guidance on assessing TPUs in both solid and solution forms, with recommendations for relevant chemical, physical, and biological tests.
• Biocompatibility Assessment: Inclusion of standard test methods (such as Practice F748 and ISO 10993) to evaluate the safe use of TPUs in contact with biological systems, noting that passing these tests does not automatically endorse material implantability.
• Physical and Chemical Properties: Detailed outline of tests for evaluating properties like tensile strength, compression, water absorption, abrasion resistance, and polymer purity.
• Processing and Fabrication: Recommendations for polymer drying, molding, extrusion, and storage to preserve material integrity throughout device manufacturing.
• Purchase Specifications: Guidance for buyers and sellers to use the standard's recommended tests and methods for preparing purchase requirements tailored to specific biomedical needs.
• Packaging and Labeling: Best practices for packaging TPUs to prevent contamination and degradation, including labeling to maintain traceability and specification compliance.

Applications

ASTM F624-09(2015)e1 is widely applicable in the biomedical device industry, supporting manufacturers, formulators, and material suppliers in:

• Medical Device Fabrication: Selecting and qualifying TPUs for products like surgical aids, catheters, tubing, and implantable components.
• Material Qualification: Ensuring that chosen polyurethane materials meet necessary physical and biocompatibility criteria for their intended clinical environment.
• Regulatory Support: Providing documented evidence for compliance with global regulatory requirements by following standardized evaluation protocols.
• Custom Device Development: Informing custom purchase specifications and material agreements between suppliers and device fabricators, based on recommended test methods and tolerances.
• Quality Control: Establishing reproducible procedures for testing material batches to assure consistency and performance in final medical devices.

Related Standards

This guide references and aligns with several key ASTM and international standards relevant to the evaluation of TPUs for biomedical use:

• ASTM F748 - Practice for Selecting Generic Biological Test Methods for Materials and Devices
• ISO 10993 - Biological Evaluation of Medical Devices
• ASTM D412 - Test Methods for Vulcanized Rubber and Thermoplastic Elastomers-Tension
• ASTM D2240 - Test Method for Rubber Property-Durometer Hardness
• ASTM D2990 - Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics
• ASTM D257, D149, D150 - Electrical properties of insulating materials
• ASTM D2857, D1238, D1544 - Polymer solution viscosity, melt flow rates, and color evaluation

These related standards complement ASTM F624 by providing detailed procedures for evaluating the key properties necessary for safe and effective use of thermoplastic polyurethanes in healthcare and medical device applications. By integrating these established test methods, ASTM F624 supports a rigorous, standardized approach to TPU material selection and device development in the biomedical field.

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.
´1
Designation: F624 − 09 (Reapproved 2015)
Standard Guide for
Evaluation of Thermoplastic Polyurethane Solids and
Solutions for Biomedical Applications
ThisstandardisissuedunderthefixeddesignationF624;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Section 1.2 was editorially corrected in May 2015.
1. Scope D149 Test Method for Dielectric Breakdown Voltage and
DielectricStrengthofSolidElectricalInsulatingMaterials
1.1 This guide covers the evaluation of thermoplastic poly-
at Commercial Power Frequencies
urethanes in both solid and solution form for biomedical
D150 Test Methods forAC Loss Characteristics and Permit-
applications. The polymers have been reacted to completion
tivity (Dielectric Constant) of Solid Electrical Insulation
and require no further chemical processing.
D257 Test Methods for DC Resistance or Conductance of
1.2 The tests and methods listed in this guide may be
Insulating Materials
referenced in specifications containing minimum required
D395 Test Methods for Rubber Property—Compression Set
values and tolerances for specific end-use products.
D412 Test Methods forVulcanized Rubber andThermoplas-
1.3 Standard tests for biocompatibility are included to aid in tic Elastomers—Tension
the assessment of safe utilization in biomedical applications. D570 Test Method for Water Absorption of Plastics
D575 Test Methods for Rubber Properties in Compression
Compliance with these criteria shall not be construed as an
endorsement of implantability. Since many compositions, D671 Test Method for Flexural Fatigue of Plastics by
Constant-Amplitude-of-Force (Withdrawn 2002)
formulations, and forms of thermoplastic polyurethanes in
solid and solution forms are within this material class, the D790 Test Methods for Flexural Properties of Unreinforced
and Reinforced Plastics and Electrical Insulating Materi-
formulator or fabricator must evaluate the biocompatibility of
the specific composition or form in the intended use and after als
D792 Test Methods for Density and Specific Gravity (Rela-
completion of all manufacturing processes including steriliza-
tion. tive Density) of Plastics by Displacement
D1238 Test Method for Melt Flow Rates of Thermoplastics
1.4 Purchase specifications may be prepared by agreement
by Extrusion Plastometer
between the buyer and seller by selection of appropriate tests
D1242 Test Methods for Resistance of Plastic Materials to
and methods from those listed applicable to the specific
Abrasion (Withdrawn 2003)
biomedical end use.
D1434 TestMethodforDeterminingGasPermeabilityChar-
1.5 This standard does not purport to address all of the
acteristics of Plastic Film and Sheeting
safety concerns, if any, associated with its use. It is the
D1544 Test Method for Color of Transparent Liquids (Gard-
responsibility of the user of this standard to establish appro-
ner Color Scale)
priate safety and health practices and determine the applica-
D1638 Methods of Testing Urethane Foam Isocyanate Raw
bility of regulatory limitations prior to use. 3
Materials (Withdrawn 1989)
D2124 Test Method forAnalysis of Components in Poly(Vi-
2. Referenced Documents
nyl Chloride) Compounds Using an Infrared Spectropho-
2.1 ASTM Standards:
tometric Technique
D2240 Test Method for Rubber Property—Durometer Hard-
ness
This guide is under the jurisdiction of ASTM Committee F04 on Medical and
Surgical Materials and Devices and is the direct responsibility of Subcommittee
D2857 Practice for Dilute Solution Viscosity of Polymers
F04.11 on Polymeric Materials.
D2990 Test Methods for Tensile, Compressive, and Flexural
Current edition approved March 1, 2015. Published May 2015. Originally
Creep and Creep-Rupture of Plastics
approved in 1981. Last previous edition approved in 2009 as F624 – 09. DOI:
10.1520/F0624-09R15E01.
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 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
F624 − 09 (2015)
D3137 Test Method for Rubber Property—Hydrolytic Sta- 5.2 DifunctionalDiisocyanates—Difunctionaldiisocyanates
bility that can be used are:
D3418 Test Method for Transition Temperatures and En- 5.2.1 Diphenylmethane 4,4-diisocyanate (MDI).
thalpies of Fusion and Crystallization of Polymers by 5.2.2 2,4-tolylene diisocyanate (TDI).
Differential Scanning Calorimetry 5.2.3 1,5-naphthalene diisocyanate.
E96/E96M Test Methods for Water Vapor Transmission of 5.2.4 1,6-hexamethylene diisocyanate (HMDI).
Materials
5.3 Chain Extenders—Chain extenders that can be used are:
F748 PracticeforSelectingGenericBiologicalTestMethods
5.3.1 Water.
for Materials and Devices
5.3.2 Glycols.
2.2 ISO Standard:
5.3.3 Aliphatic and aromatic diamines.
ISO 10993 Biological Evaluation of Medical Devices
5.4 Chain-Terminating Agents—Chain-terminating agents
suitable for use are:
3. Terminology
5.4.1 Monofunctional alcohols, such as methanol or etha-
3.1 Definitions:
nol.
3.1.1 chain extender—(1) an active hydrogen containing a
5.4.2 Monofunctional amines, such as dibutylamine or di-
compound such as a diol or diamine used to increase the
ethylamine.
molecular weight of an isocyanate-terminated prepolymer by
5.5 Catalysts—Stannous octoate is suitable for prepolymer
chemical reaction; (2) a diisocyanate used to extend a polyol-
preparation.
terminated polyurethane by chemical reaction.
5.6 Optional Additives:
3.1.2 chain terminating agent—an active hydrogen contain-
5.6.1 Pigments and dyes, such as titanium dioxide and
ing a compound such as a monofunctional alcohol, amine, or
copper phthalocyanine blue.
acid that reacts with the isocyanate group of a prepolymer to
5.6.2 Radiopaque materials, such as barium sulfate.
prevent further chain growth.
5.6.3 Antiblocking agents and lubricants, such as natural
3.1.3 linear polyurethane—a polymer whose backbone con-
and synthetic waxes.
sists of urethane groups joined by hydrocarbon chains with
5.6.4 Optical brighteners, antioxidants, and light and heat
little or no crosslinking.
stabilizers.
3.1.4 segmented polyurethane—A family of polymers in
5.6.5 The basic polymer bought may contain, as agreed
which ester or ether groups, connected by hydrocarbon chains,
upon between the purchaser and supplier, optional adjunct
occur as blocks that are coupled by urethane and urea groups.
substances required in the production of the polymer or
3.1.5 thermoplastic polyurethane—linear or segmented intended end use product, provided these substances are in
polyurethanes that can be melted for
...