ASTM F604-94

Specification for Silicone Elastomers Used in Medical Applications (Withdrawn 2001)

SCOPE
1.1 This specification covers silicone elastomers intended for use as materials of construction for fabrication of medical devices.
1.2 Variations in ingredients, processing, and vulcanization (crosslinking/cure) systems of silicone elastomer are necessary to achieve the properties required in specific medical device applications.
1.2.1 An alphabetical/numerical code abbreviation is defined in this specification as what may be used to specify ingredients, crosslinking systems, processing conditions, and physical properties of many silicone elastomers used in medical device applications by a standard, abbreviated designation.
1.3 In all cases where the provisions of this specification are in conflict with those of the detailed specifications for a particular product, the latter shall take precedence.
1.3.1 When silicone elastomers are used in medical device applications where the materials requirements cannot be completely achieved by the technology prescribed in this specification, it may be necessary to adjust ingredients, processing, or cure systems to a greater extent to obtain the properties needed in these specific medical device applications.
1.3.1.1 When silicone elastomers are adjusted more extensively than prescribed in this specification, such adjustments shall be completely described and controlled in specifications for each specific material.
1.3.1.2 All sections of this specification that contain requirements pertinent to safety and effectiveness apply to all silicone elastomers used as materials of construction for medical devices, including those adjusted more broadly than defined in this specification.
1.4 While silicone elastomers have demonstrated excellent biocompatibility in medical device applications, the biocompatibility of silicone elastomers as a generic class has not been established. Many compositions and formulations are possible. Manufacturing practices, facilities, controls, process validation, and other considerations that ensure batch-to-batch duplication, assurance of identity, and quality of ingredients, as well as freedom from contamination or cross-contamination may vary widely within the silicone elastomer industry. Medical device manufacturers must ensure safety and effectiveness of each specific composition or formulation from each supplier in its intended applications. Historic, clinical, and biocompatibility data are pertinent prospectively only when all compounding, formulating, and fabrication are done in accordance with the provisions of Good Manufacturing Practice Regulations,  which help ensure medical materials and devices are reasonably duplicated each time they are manufactured.
1.5 This specification is intended to assist in the development of specifications for formulated silicone elastomer compounds. It is also recommended for use in materials and finished device labeling to specify the type or types of silicone elastomers contained.
1.6 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: Withdrawn
• Publication Date: 31-Dec-1993
• Withdrawal Date: 09-Jan-2001
• ICS: 11.120.20 - Wound dressings and compresses
• ICS: 83.060 - Rubber
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.11 - Polymeric Materials

Relations

• Referred By: ASTM F881-94(2022) - Standard Specification for Silicone Elastomer Facial Implants
• Effective Date: 01-Jan-1994
• Referred By: ASTM F2051-00(2022) - Standard Specification for Implantable Saline-Filled Breast Prostheses
• Effective Date: 01-Jan-1994
• Referred By: ASTM F647-22 - Standard Practice for Evaluating and Specifying Implantable Shunt Assemblies for Neurosurgical Application
• Effective Date: 01-Jan-1994

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 604 – 94
Standard Specification for
Silicone Elastomers Used in Medical Applications
This standard is issued under the fixed designation F 604; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope device manufacturers must ensure safety and effectiveness of
each specific composition or formulation from each supplier in
1.1 This specification covers silicone elastomers intended
its intended applications. Historic, clinical, and biocompatibil-
for use as materials of construction for fabrication of medical
ity data are pertinent prospectively only when all compound-
devices.
ing, formulating, and fabrication are done in accordance with
1.2 Variations in ingredients, processing, and vulcanization
the provisions of Good Manufacturing Practice Regulations,
(crosslinking/cure) systems of silicone elastomer are necessary
which help ensure medical materials and devices are reason-
to achieve the properties required in specific medical device
ably duplicated each time they are manufactured.
applications.
1.5 This specification is intended to assist in the develop-
1.2.1 An alphabetical/numerical code abbreviation is de-
ment of specifications for formulated silicone elastomer com-
fined in this specification as what may be used to specify
pounds. It is also recommended for use in materials and
ingredients, crosslinking systems, processing conditions, and
finished device labeling to specify the type or types of silicone
physical properties of many silicone elastomers used in medi-
elastomers contained.
cal device applications by a standard, abbreviated designation.
1.6 This standard does not purport to address all of the
1.3 In all cases where the provisions of this specification are
safety concerns, if any, associated with its use. It is the
in conflict with those of the detailed specifications for a
responsibility of the user of this standard to establish appro-
particular product, the latter shall take precedence.
priate safety and health practices and determine the applica-
1.3.1 When silicone elastomers are used in medical device
bility of regulatory limitations prior to use.
applications where the materials requirements cannot be com-
pletely achieved by the technology prescribed in this specifi-
2. Referenced Documents
cation, it may be necessary to adjust ingredients, processing, or
2.1 ASTM Standards:
cure systems to a greater extent to obtain the properties needed
D 149 Test Method for Dielectric Breakdown Voltage and
in these specific medical device applications.
Dielectric Strength of Solid Electrical Insulating Materials
1.3.1.1 When silicone elastomers are adjusted more exten-
at Commercial Power Frequencies
sively than prescribed in this specification, such adjustments
D 150 Test Methods for A-C Loss Characteristics and
shall be completely described and controlled in specifications
Permittivity (Dielectric Constant) of Solid Electrical Insu-
for each specific material.
lating Materials
1.3.1.2 All sections of this specification that contain require-
D 257 Test Methods for D-C Resistance or Conductance of
ments pertinent to safety and effectiveness apply to all silicone
Insulating Materials
elastomers used as materials of construction for medical
D 395 Test Methods for Rubber Property—Compression
devices, including those adjusted more broadly than defined in
Set
this specification.
D 412 Test Methods for Rubber Properties in Tension
1.4 While silicone elastomers have demonstrated excellent
D 430 Test Methods for Rubber Deterioration—Dynamic
biocompatibility in medical device applications, the biocom-
Fatigue
patibility of silicone elastomers as a generic class has not been
D 570 Test Method for Water Absorption of Plastics
established. Many compositions and formulations are possible.
D 624 Test Method for Tear Strength of Conventional
Manufacturing practices, facilities, controls, process valida-
Vulcanized Rubber and Thermoplastic Elastomers
tion, and other considerations that ensure batch-to-batch dupli-
D 792 Test Methods for Specific Gravity (Relative Density)
cation, assurance of identity, and quality of ingredients, as well
and Density of Plastics by Displacement
as freedom from contamination or cross-contamination may
D 813 Test Method for Rubber Deterioration—Crack
vary widely within the silicone elastomer industry. Medical
Growth
This specification is under the jurisdiction of ASTM Committee F-4 on Medical
and Surgical Materials and Devices and is the direct responsibility of Subcommittee Federal Register, Vol 43, No. 141, Friday, July 21, 1978, Part II.
F04.11 on Polymeric Materials. Annual Book of ASTM Standards, Vol 10.01.
Current edition approved March 15, 1994. Published July 1994. Originally Annual Book of ASTM Standards, Vol 09.01.
published as F 604 – 78. Last previous edition F 604 – 87. Annual Book of ASTM Standards, Vol 08.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 604
D 814 Test Method for Rubber Property—Vapor Transmis- 3.1.4 post cure—typically refers to heat processing of
sion of Volatile Liquids molded or fabricated silicone elastomer parts done in an air
D 865 Test Method for Rubber—Deterioration by Heating
circulating oven for a specified time and temperature. Post cure
in Air (Test Tube Enclosure) is generally necessary to complete the vulcanization/
D 926 Test Method for Rubber Property—Plasticity and
crosslinking chemistry, stabilize properties, and drive off any
Recovery (Parallel Plate Method) volatile materials such as residuals or break down products of
D 955 Test Method of Measuring Shrinkage from Mold
catalysts generated during vulcanization.
Dimensions of Molded Plastics
3.1.5 silicone compound—an unvulcanized, uniformly
D 991 Test Method for Rubber Property—Volume Resistiv-
blended formulation containing silicone polymers and fillers.
ity of Electrically Conductive and Antistatic Products
Silicone compounds may be one-part or two-part. One-part
D 1349 Practice for Rubber—Standard Temperatures for
compounds may be supplied either catalyzed and ready to
Testing
process, or uncatalyzed, requiring the addition of a catalyst
D 1418 Practice for Rubber and Rubber Latices—
prior to use. Two-part silicone compounds must be blended
Nomenclature
together prior to use and may have limited shelf life after
D 1566 Terminology Relating to Rubber
blending.
D 1898 Practice for Sampling of Plastics
3.1.6 silicone elastomer—an elastomer containing
D 2240 Test Method for Rubber Property—Durometer
crosslinked silicone polymer and filler, typically fumed silica.
Hardness
3.1.7 silicone polymer—polymer chains with chemical
D 3137 Test Method for Rubber Property—Hydrolytic Sta-
structure of repeating diorganosiloxy groups, typically repeat-
bility
ing dimethylsiloxy groups in elastomers used in medical device
F 619 Practice for Extraction of Medical Plastics
applications. Polymer chains contain repeating silicon and
F 748 Practice for Selecting Generic Biological Test Meth-
oxygen atoms.
ods for Materials and Devices
3.1.8 vulcanization—an irreversible process where covalent
F 813 Practice for Direct Contact Cell Culture Evaluation of
chemical crosslinks are formed between silicone polymers
Materials for Medical Devices
chains contained in silicone elastomer compounds. During
F 1251 Terminology Relating to Polymeric Biomaterials in
vulcanization the material changes from a flowable compound,
Medical and Surgical Devices
which can vary widely in viscosity, to an elastomeric material,
2.2 ANSI Standard:
which cannot again be reshaped except by its physical destruc-
Z1.8 General Requirements for a Quality Program
tion.
2.3 AAMI Standard:
EOS-DE-O Sterilization Standard
4. Fabrication, Vulcanization, Postcure, and Physical
2.4 United States Pharmacopeia, XXII Edition, 1989
Properties
2.5 Federal Register, Title 21, Part 820
4.1 Fabrication and vulcanization conditions shall be desig-
nated by a letter code as listed in 4.1.1, followed by numerical
designations of time/temperature. Time shall be listed as h
3. Terminology
(hours), m (minutes), or s (seconds). Temperature shall be
3.1 Definitions:
defined as °C or °F.
3.1.1 catalyst/crosslinking agent—an ingredient contained
4.1.1 Fabrication Codes:
in a silicone elastomer formulation that either initiates or is a
CM compression molding
reactant in the crosslinking chemistry when the material is
TM transfer molding
vulcanized. E extrusion
D dispersion dipping
3.1.2 filler—a finely divided, solid material that is inti-
CA calendaring
mately blended with silicone polymers during mixing and
HL hand lay-up
Z other, to be specified
compounding to achieve specific properties. The filler used
with silicone elastomer is typically high surface area, amor-
4.2 Postcure shall be designated by the letters “PC” fol-
phous, fumed silica, an ingredient essential to high strength and
lowed by numerical designation of time/temperature (h/
elastomeric physical properties.
temperature° F or °C). (See Practice D 1349, Section 2.)
3.1.3 lot or batch—material with a fixed, specified formu-
Designate as “PC none” when no postcure has been used or
lation made in a single, continuous manufacturing run from
when none is recommended in material processing.
single lots of all ingredients and processed by the same
4.3 Physical Properties—Measurements of durometer, ten-
techniques at same conditions.
sile strength, and elongation are typically considered essential
for defining and controlling a silicone elastomer. Designate in
6 series as durometer/tensile strength/elongation as defined in
Annual Book of ASTM Standards, Vol 13.01.
Available from American National Standards Institute, 11 West 42nd St., 13th 4.3.1, 4.3.2, and 4.3.3, respectively.
Floor, New York, NY 10036.
4.3.1 Durometer (Hardness), Shore A—Measure in keeping
Available from Association for Advancement of Medical Instrumentation, 1500
with Test Method D 2240. Designate by D followed by a
Wilson Blvd., Suite 417, Arlington, VA 22209.
Available from Mack Publishing Co., Easton, PA. number as selected from the following:
F 604
TABLE 1
Designation Hardness (Shore A, Test Method
D 2240)
NOTE 1—Additional test designation of C, die B; 1.75 3 10 N/M (100
Nominal6 5 Point Range
ppi) indicates testing by Test Method D 624, die B with minimum value
of 1.74 N/M (100 ppi) is required. When additional testing is required it
0 Below 5
110 6 5
must be specified in enough detail to provide a complete explanation of
220 6 5
both the testing to be done and the minimum values required.
330 6 5
Test
440 6 5
Suffix Test
Methods
550 6 5
660 6 5
A specific gravity D 792
770 6 5
B tensile stress at specified elongation D 412
880 6 5
C tear strength D 624
9 see Note for special range requirement
D compression set D 395
E dielectrical properties D 149
4.3.2 Tensile Strength—Measure in keeping with Test Meth-
F ac loss characteristics D 150
ods D 412. Designate by “TS” followed by a three-digit code
G dc resistance or conductance D 257
H volume resistivity of conductive materials D 991
that shall designate the minimum allowable tensile strength (in
I resistance to fatigue flexing D 430
MPa) as follows:
J resistance of fatigue crack growth D 813
Code Tensile Strength, min, MPa (psi) K water absorption D 570
007 5 0.7 (100) L vapor transmission D 814
035 5 3.5 (500) M heat resistance in air D 865
070 5 7.0 (1000) N plasticity, unvulcanized materials D 926
105 5 10.5 (1500) O shrinkage from mold D 955
000 5 see Note for special range or requirement P hydrolytic stability D 3137
Z other, such as analysis for metals content, extract-
4.3.3 Elongation—Measure using Test Methods D 412.
able metals, foreign particles (type and count), and
the like—to be specified
Designate by E followed by a two-digit code that shall define
the minimum elongation in percent as follows:
Code Elongation, %
tive codes for the composition and other characteristics of
10 5 100
29 5 290
future new formulations with improved properties without the
99 5 990
need for developing a completely new standards.
00 5 see Note for special range or requirement
6.3 This specification allows the incorporation of future new
NOTE 1—Physical properties designated by D5/TS 070/E 99 indicate
test methods to keep pace with changing silicone elastomer
property requirements are durometer Shore A50 6 5; tensile strength, 7.0
technology in medical device requirements.
MPa (1000 psi), minimum; and elongation; 990 %, minimum.
7. Polymers, Fillers, and Catalyst/Crosslinking Agent and
5. Additional Property Requirements
Cure System
5.1 Some medical device applications require testing and
7.1 Polymers:
control of additional properties. Such testing may also be
10,11
7.1.1 Polymer Composition —The following system for
informational or needed to help ensure materials reproducibil-
designation of silicone polymers is based, in part, on Practice
ity as opposed to being required in an intended use. In
D 1418. In this practice the letter Q designates alternate
preparing materials specifications, avoiding unnecessary re-
silicone and oxygen atoms in the polymer chain.
quirements that have no potential to improve ensurance of
medical device safety and performance is recommended. Table Type Designation of Polymer
1 lists some of the various additional tests that areavailable.
MQ Polymer having only methyl substituent groups on poly-
Designate additional tests by the letters “AT” followed by the
mer chains, such as dimethylpolysiloxane.
VMQ Polymer having both methyl and vinyl substituent groups
number for the test from Table 1. It may be necessary to
on polymer chains.
provide additional information to further define the testing
FVMQ Polymers having 3,3,3-trifluoropropyl, vinyl, and methyl
required. If testing involves time and temperature, designate as
substituent groups on polymer chains.
VMP 5 M 5 Q Polymers having methylvinylsiloxy, diphenylsiloxy, and
defined in 4.1. When the minimum value require list as the last
dimethylsiloxy groups on polymer chains.
item in the additional testing designation.
ZQ Other polymer composition, to be specified.
6. Significance and Use
7.1.1.1 Silicone elastomers containing copolymers or blends
or blends having both dimethylsiloxy and methyl(phenyl)
6.1 This specification is intended to provide guidance for
siloxy groups in the polymer chains are not recommended for
the specifying and selecting silicone elastomers for medical
use in medical de
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