ASTM F1925-99(2005)
(Specification)Standard Specification for Virgin Poly(L-Lactic Acid) Resin for Surgical Implants
Standard Specification for Virgin Poly(L-Lactic Acid) Resin for Surgical Implants
ABSTRACT
This specification covers virgin poly(L-lactic acid) resin (PLLA resin) intended for use in surgical implants. This specification does not cover stereoisomeric compositions based on various D, L, or DL copolymer ratios. This specification addresses material characteristics of virgin poly(L-lactic acid) resin and does not apply to packaged and sterilized finished implants fabricated from this material. The virgin polymer shall be a homopolymer of L-lactide with the prescribed density. The molecular mass of the virgin polymer shall be indicated by relative solution viscosity (in chloroform). In addition, the weight average molecular mass and molecular mass distributions may be determined by gel permeation chromatography The virgin polymer shall be identified as a polylactide by infrared or 1H-NMR spectroscopy. Typical infrared transmission and 1H-NMR spectra are shown. The virgin polymer shall have a specific optical rotation (in dichloromethane) and residual monomer content within the prescribe values, and shall conform to the chemical and physical property requirements specified for: residual solvent, residual water, residual tin, heavy metals, and sulfated ash. The following test methods shall be used: (1) Karl-Fischer titration and (2) atomic absorption-emission (AA) spectroscopy or inductively coupled plasma (ICP) spectroscopy. Considerations for biocompatibility of the material from a human implant perspective is also given.
SCOPE
1.1 This specification covers virgin poly(L-lactic acid) resin (or abbreviated as PLLA resin) intended for use in surgical implants. This specification does not cover stereoisomeric composition based on various D, L, DL copolymer ratios.
1.2 This specification addresses material characteristics of virgin poly(L-lactic acid) resin and does not apply to packaged and sterilized finished implants fabricated from this material.
1.3 As with any material, some characteristics may be altered by processing techniques (such as molding, extrusion, machining, assembly, sterilization, etc.) required for the production of a specific part or device. Therefore, properties of fabricated forms of this resin should be evaluated using those test methods which are appropriate to assure safety and efficacy.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 The following precautionary statement pertains only to the test method portion, Section 6, 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: F 1925 – 99 (Reapproved 2005)
Standard Specification for
Virgin Poly(L-Lactic Acid) Resin for Surgical Implants
This standard is issued under the fixed designation F1925; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D3593 Test Method for Molecular Weight Averages and
Molecular Weight Distribution of Certain Polymers by
1.1 Thisspecificationcoversvirginpoly(L-lacticacid)resin
Liquid Size-Exclusion Chromatography (Gel Permeation
(or abbreviated as PLLA resin) intended for use in surgical
Chromatography - GPC) Using Universal Calibration
implants. This specification does not cover stereoisomeric
D3892 Practice for Packaging of Plastics
compositions based on various D, L, or DL copolymer ratios.
F748 Practice for Selecting Generic Biological Test Meth-
1.2 This specification addresses material characteristics of
ods for Materials and Devices
virginpoly(L-lacticacid)resinanddoesnotapplytopackaged
2.2 ISO Standard:
and sterilized finished implants fabricated from this material.
ISO 10993-9, Biological Evaluation of Medical Devices,
1.3 As with any material, some characteristics may be
Part 9—Degradation of Materials Related to Biological
altered by processing techniques (such as molding, extrusion,
Testing, Annex A
machining, assembly, sterilization, and so forth) required for
the production of a specific part or device. Therefore, proper-
3. Terminology
ties of fabricated forms of this resin should be evaluated using
3.1 Definitions of Terms Specific to This Standard:
those test methods which are appropriate to assure safety and
3.1.1 generic property—that property which is determined
efficacy.
solely by the chemical composition and structure of the virgin
1.4 The values stated in SI units are to be regarded as the
polymer.
standard.
3.1.2 virgin polymer—the form of poly(L-lactic acid) as
1.5 This standard does not purport to address all of the
obtained from the manufacturer and before fabrication into a
safety concerns, if any, associated with its use. It is the
medical device.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Virgin Poly(L-Lactic Acid) Resin Requirements
bility of regulatory limitations prior to use.
4.1 Generic Properties:
2. Referenced Documents 4.1.1 The virgin polymer shall be a homopolymer of
2 L-lactide with a density between 1.20 and 1.28 g/cm (see 6.5
2.1 ASTM Standards:
for evaluation method).
D1505 Test Method for Density of Plastics by the Density-
4.1.2 The molecular mass of the virgin polymer shall be
Gradient Technique
indicated by relative solution viscosity in accordance with 6.2.
D1898 Practice for Sampling of Plastics
In addition to solution viscosity (but not in place of), weight
D2857 Practice for Dilute Solution Viscosity of Polymers
average molecular mass and molecular mass distributions may
D3536 Test Method for Molecular Weight Averages and
be determined by gel permeation chromatography (GPC)
Molecular Weight Distribution by Liquid Exclusion Chro-
according to Test Methods D3536 or D3593.
matography (Gel Permeation Chromatography - GPC)
4.1.3 The virgin polymer shall be identified as a polylactide
by infrared or H-NMR spectroscopy.
This specification is under the jurisdiction of ASTM Committee F04 on
4.1.3.1 The virgin polymer shall yield an infrared spectrum
Medical Surgical Materials and Devices and is the direct responsibility of
whichexhibitsmajorabsorptionbandsonlyatthewavelengths
Subcommittee F04.11 on Polymeric Materials.
that appear in a suitable reference spectrum.Atypical infrared
Current edition approved Mar. 1, 2005. Published March 2005. Originally
e1
approved in 1998. Last previous edition approved in 1999 as F1925–99 . transmission spectrum is shown in Fig. 1.
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F 1925 – 99 (2005)
FIG. 1 Poly(L-Lactic Acid) Resin Infrared Spectrum
4.1.3.2 Additional absorption bands may be indicative of
known,orunknown,impuritiesincludingresidualsolventsand
catalysts (refer to residual solvent limits specified in Table 1).
4.1.3.3 Aninfraredspectrumcannotdistinguishbetweenthe
different available stereoisomeric polylactic acids. It is used
here only as a means of identifying the material as a polylac-
tide.
4.1.3.4 The virgin polymer shall yield a H-NMR spectrum
which exhibits major absorption bands only at the frequencies
thatappearinasuitablereferencespectrum.Atypical H-NMR
spectrum is shown in Fig. 2.
4.1.3.5 Additional absorption bands may be indicative of
known,orunknown,impuritiesincludingresidualsolventsand
monomers, and catalysts (refer to residual solvent, monomer,
and tin (catalyst) limits specified in Table 1) and 4.1.5.
4.1.3.6 A H-NMR spectrum cannot distinguish between
thedifferentavailablestereoisomericpolylacticacids.Itisused
here only as a means of identifying the material as a polylac-
tide.
4.1.4 The virgin polymer shall have a specific optical
rotation between −155 and −160° when measured as specified
in 6.3.
FIG. 2 Poly(L-Lactic Acid) Resin H-NMR Spectrum
TABLE 1 Physical/Chemical Property Requirements of Virgin
4.1.5 The virgin polymer shall have a residual monomer
Poly(L-Lactic Acid) Resins
contentlessthanorequalto2.0%whenassayedinaccordance
Heavy
Residual
Residual Residual Tin Metals, Sulfated with 6.4. Virgin polymers having inherent viscosities greater
Analyte Solvent(s),
Water, % (Sn), ppm (as Lead), Ash, %
t
...
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