Characterization of Porosity in Porous Polymer Implant Materials

摘要

The investigation of the methods of characterizing the porosity of two porous polymeric implant materials have been concluded with the work discussed in this report. The two materials, a porous polyethylene (PPE) and a porous composite of polytetrafluoroethylene and carbon (PTFE-C) have been further investigated by the method of quantitative microscopy. The mean pore volume fractions of 30 samples each of PPE and PTFE-C were found to be 0.48 and 0.69, respectively, and are in good agreement with other measurements of this quantity. The mean intercept length for PPE was found to be 76 micrometers, and for PTFE-C, 67 micrometers. Both values are somewhat larger than the average interconnecting pore 'diameters' as measured by mercury porosimetry. The reproducibility of mercury porosimetry data has been tested by examining 16 samples of PTFE-C in thin sheet form and 6 samples of laminated blocks. The mean and standard deviation of four parameters derived from the mercury intrusion curves were calculated. A high correlation was found between the specific pore volume and the position of the mercury intrusion curve along the pressure axis. A number of random errors pertaining to mercury porosimetry were discovered and are discussed in this report.