1.1 This test method covers the determination of mechanical behavior of polymericbiomaterials by small punch testing of miniature disk specimens (0.5 mm in thicknessand 6.4 mm in diameter). The test method has been established for characterizingsurgical materials after ram extrusion or compression molding (1-3) 2; forevaluating as-manufactured implants and sterilization method effects (4, 5);as well as for testing of implants that have been retrieved (explanted) from thehuman body (6, 7).
1.2 The results of the small punch test, namely the peak load, ultimate displacement,ultimate load, and work to failure, provide metrics of the yielding, ultimatestrength, ductility, and toughness under multiaxial loading conditions. Because themechanical behavior can be different when loaded under uniaxial and multiaxialloading conditions (8), the small punch test provides a complementarymechanical testing technique to the uniaxial tensile test. However, it should benoted that the small punch test results may not correlate with uniaxial tensile testresults.
1.3 In addition to its use as a research tool in implant retrieval analysis, thesmall punch test can be used as a laboratory screening test to evaluate newmaterials with minimal material waste (1).
1.4 The small punch test has been applied to other polymers, including polymethylmethacrylate (PMMA) bone cement, polyacetal, and high density polyethylene (HDPE),ultra high molecular weight polyethylene (UHMWPE), and polyetheretherketone (PEEK)(2, 3, 5, 9, 10). This standard outlines general guidelines for the smallpunch testing of implantable polymers.
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 standardto establish appropriate safety, health, and environmental practices anddetermine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationallyrecognized principles on standardization established in the Decision onPrinciples for the Development of International Standards, Guides andRecommendations issued by the World Trade Organization Technical Barriers toTrade (TBT) Committee.
