Characterization of porous glass fiber-reinforced composite (FRC) implant structures: porosity and mechanical properties. 
The aim of this study was to characterize the microstructure and mechanical properties of porous fiber-reinforced composites (FRC).  Implants made of the FRC structures are intended for cranial applications.  The FRC specimens were prepared by impregnating E-glass fiber sheet with non-resorbable bifunctional bis-phenyl glycidyl dimethacrylate and triethylene glycol dimethacrylate resin matrix.  Four groups of porous FRC specimens were prepared with a different amount of resin matrix.  Control group contained specimens of fibers, which were bound together with sizing only.  Microstructure of the specimens was analyzed using a micro computed tomography (micro-CT) based method.  Mechanical properties of the specimens were measured with a tensile test.  The amount of resin matrix in the specimens had an effect on the microstructure.  Total porosity was 59.5 % (median) in the group with the lowest resin content and 11.2 % (median) in the group with the highest resin content.  In control group, total porosity was 94.2 % (median).  Correlations with resin content were obtained for all micro-CT based parameters except TbPf.  The tensile strength of the composites was 21.3 MPa (median) in the group with the highest resin content and 43.4 MPa (median) in the group with the highest resin content.  The tensile strength in control group was 18.9 MPa (median).  There were strong correlations between the tensile strength of the specimens and most of the micro-CT based parameters.  This experiment suggests that porous FRC structures may have the potential for use in implants for cranial bone reconstructions, provided further relevant in vitro and in vivo tests are performed.