On the characterization of porosity in PTFE-carbon composite implant materials by mercury porosimetry.
Questions have been raised about the use of mercury intrusion porosimetry to measure interconnecting pore sizes and void volumes in relatively soft and flexible materials such as porous implant composites of PTFE and carbon fibers. We have studied the effect of precompression of one such commercial composite on the mercury intrusion curves which cover all pore diameters greater than about 16 microns, the range of interest for tissue ingrowth applications. Prior compression by a pressure 20% greater than that encountered by the material during a mercury intrusion experiment did not change the ensuing pore size distribution curve, as compared with a noncompressed sample. Deformation of the material at higher pressures sufficient to decrease the sample volume inelastically by 17, 33, and 67% changed the shape of the mercury intrusion curves significantly, indicating that this technique can be used to detect prior deformation of an "unknown" sample. In the undeformed material, less than 15% of the total void as measured by mercury porosimetry consists of interconnecting pores greater than 100 microns in diameter and more than 50% of the void volume is composed of pores less than 40 microns in diameter.
D001672:Biocompatible Materials / Q000592:standards*; D002244:Carbon; D008628:Mercury; D008722:Methods; D011138:Polytetrafluoroethylene / Q000032:analysis / Q000592:standards*; D011312:Pressure; D011428:Proplast / Q000592:standards; D019736:Prostheses and Implants; D011786:Quality Control
D001672:Biocompatible Materials; D011428:Proplast; D002244:Carbon; D011138:Polytetrafluoroethylene; D008628:Mercury