ASTM F2579 : 24

1.1 This specification covers virgin amorphous poly(lactide) homopolymer and poly(lactide-co-glycolide) copolymer resins intended for use in surgical implants. The poly(dl-lactide) homopolymers covered by this specification are considered to be amorphous (that is, void of crystallinity) and are polymerized either from meso-lactide or from equimolar (racemic) combinations of d-lactide and l-lactide. The poly(dl-lactide-co-glycolide) copolymers covered by this specification are also considered to be amorphous and are co-polymerized from a combination of glycolide and either meso-lactide or racemic quantities of d-lactide and l-lactide, and typically possess nominal mole fractions that equal or exceed 50 % lactide.

1.2 Since poly(glycolide) is commonly abbreviated as PGA for poly(glycolic acid) and poly(lactide) is commonly abbreviated as PLA for poly(lactic acid), these polymers are commonly referred to as PGA, PLA, and PLA:PGA resins for the hydrolytic byproducts to which they respectively degrade. PLA is a term that carries no stereoisomeric specificity and therefore encompasses both the amorphous atactic/syndiotactic dl-lactide-based polymers and copolymers as well as the isotactic d-PLA and l-PLA moieties, each of which carries potential for crystallization. Therefore, specific reference to dl-PLA is essential to appropriately differentiate the amorphous atactic/syndiotactic dl-lactide-based polymers and copolymers covered by this specification. Thus, inclusion of stereoisomeric specificity within the lactic acid-based acronyms results in the following: poly(l-lactide) as PlLA for poly(l-lactic acid), poly(d-lactide) as PdLA for poly(d-lactic acid), and poly(dl-lactide) as PdlLA for poly(dl-lactic acid).

1.3 This specification covers virgin amorphous poly(lactide)-based resins able to be fully solvated at 30 °C by either methylene chloride (dichloromethane) or chloroform (trichloromethane).

1.4 This specification is not applicable to lactide-based polymers or copolymers that possess isotactic polymeric segments sufficient in size to carry potential for lactide-based crystallization, which are covered by Specification F1925 and typically possess nominal mole fractions that equal or exceed 50 % l-lactide. This specification is not applicable to block copolymers or to polymers or copolymers synthesized from combinations of d-lactide and l-lactide that differ by more than 1.5 total mole percent (1.5 % of total moles) as covered by Specification F1925. The presence of a crystalline endotherm indicates semi-crystallinity. The percentage and morphology of the crystalline phase are highly dependent on processing, and in particular on the thermal history of the material. Therefore, the thermal properties and percent crystallinity of the virgin polymer resin (with exeption of melting temperature) are not necessarily indicative of final product quality or crystallinity. A resin may be semi-crystalline “as polymerized” but amorphous in a finished product form.

1.5 This specification is not applicable to lactide-co-glycolide copolymers that possess glycolide segments sufficient in size to deliver potential for glycolide-based crystallization, thereby requiring fluorinated solvents for complete dissolution under room temperature conditions. This specification is not applicable to lactide-co-glycolide copolymers with glycolide mole fractions greater than or equal to 70 % (65.3 % in mass fraction), which are covered by Specification F2313.

1.6 This specification addresses material characteristics of virgin amorphous poly(lactide)-based resins intended for use in surgical implants and does not apply to packaged and sterilized finished implants fabricated from these materials, nor does it address the characteristics of resins with compounded materials such as dyes, polymeric or ceramic compounds, or any other additives.

1.7 As with any material, some characteristics may be altered by processing techniques (such as molding, extrusion, machining, assembly, sterilization, and so forth) required for the production of a specific part or device. Therefore, properties of fabricated forms of this resin should be evaluated independently using appropriate test methods to ensure safety and efficacy.

1.8 Biocompatibility testing is not a requirement since this specification is not intended to cover fabricated devices. While biocompatibility testing of resin may provide an early indication of potential safety, biocompatibility analysis of the final finished device is required to determine safety and suitability for any implant device. Refer to Supplementary Requirement S1 of this standard and Guide F2902 for relevant biocompatibility information.

1.9 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.10 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.

1.11 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.