ASTM F1925-22 PDF

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 semi-crystalline poly(l-lactide) or poly(d-lactide) homopolymer resins intended for use in surgical implants. This specification also covers semi-crystalline resins of l-lactide copolymerized with other bioabsorbable monomers including, but not limited to, glycolide, d-lactide, and dl-lactide. The poly(l-lactide) or poly(d-lactide) based homopolymers and copolymers covered by this specification possess lactide segments of sufficient length to allow potential for their crystallization upon annealing. 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. 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 is applicable to lactide-based polymers or copolymers that possess isotactic polymeric segments sufficient in size to carry potential for lactide-based crystallization. Such polymers typically possess nominal mole fractions that equal or exceed 50 % l-lactide. This specification is particularly applicable to isotactic-lactide based 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). 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. This specification is not applicable to amorphous polymers or copolymers synthesized from combinations of d-lactide and l-lactide that differ by less than 1.5 total mole percent (1.5 % of total moles) as covered by Specification F2579. 1.4 This specification covers virgin semi-crystalline poly(lactide)-based resins able to be fully solvated at 30 °C by either methylene chloride (dichloromethane) or chloroform (tr...