Effect of notch sensitivity on the mechanical properties of HA/PEEK functional gradient biocomposites

Abstract

<jats:title>Abstract</jats:title> <jats:p>Biomaterials used as loading-bearing orthopedic implants usually require various excellent properties such as mechanical, bioactive and bio-tribological performances. Moreover, all of the orthopedic applications feature stress concentrations (notch sensitivity) in their design. In the present work, hydroxyapatite-reinforced polyetheretherketone functional gradient biocomposites (HA/PEEK FGBm) were successfully prepared by the layer stacking method combined with hot pressing molding technology. The effects of notch geometry on the stress-strain behavior of HA/PEEK FGBm were evaluated. The fracture morphology was investigated by scanning electron microscopy (SEM). The study of the stress-strain behavior indicated that the tensile and flexural stresses of HA/PEEK FGBm linearly increased with increasing strain under all the notch sensitivities. The fracture strain of the biocomposites decreased with increasing stress concentration factor and total HA content in the functional biocomposites. Moreover, the tensile and flexural strengths of HA/PEEK FGBm were lower than those of homogeneous HA/PEEK biocomposites. The SEM observation of the fracture micro-morphology showed that the fracture mechanism of HA/PEEK FGBm was gradually controlled by the brittle fracture process. Furthermore, both the tensile and the flexural strengths of HA/PEEK FGBm decreased with the increase in stress concentration factor and total HA content in the biocomposites.</jats:p>

Mechanical bending strength of (Bi0.5Na0.5) TiO3-based lead-Free piezoelectric ceramics

“…From the Weibull plots of the three-point bending strength on the basis of JIS, values of the average bending strength A of OF-BNT ceramics sintered at 1100 • C for 2, 12 and 24 h were 217, 195 and 187 MPa, respectively. These values are almost the same case as with another BNT-based solid solutions in the previous reports [6][7][8], and are two or three times larger than those of conventional piezoelectric ceramics such as PZT or PZT-based ceramics. From SEM observation, after the bending test, the fracture surface of all samples were transgranular fracture, which were also similar to those of BNT-based ceramics in the previous reports [8].…”

“…The BNT ceramic exhibits a large remanent polarization, P r = 38 C/cm 2 , piezoelectric strain constant, d 33 = 80 pC/N and the depolarization temperature, T d = 185 • C [3][4][5]. In addition, many BNT-based solid solutions such as BNT-BaTiO 3 [BT], BNT-(Bi 0.5 K 0.5 )TiO 3 -BaTiO 3 [BNKBT], etc [6][7][8][9][10][11] have been reported as one of good candidate lead-free materials for many piezoelectric applications.…”

“…On the other hand, researches about mechanical strength of BNT-based ceramics are not so many [6][7][8]. According to limited reports, the bending strength of BNT-based ceramics were 150 ∼ 200 MPa [6][7][8].…”

“…On the other hand, researches about mechanical strength of BNT-based ceramics are not so many [6][7][8]. According to limited reports, the bending strength of BNT-based ceramics were 150 ∼ 200 MPa [6][7][8]. All these reports show that the bending strength of BNT-based ceramics are higher than those in PZT-based ceramics, which are good for piezoelectric applications.…”

Preparation and Tribological Investigations of PVA-H/HA Composites

“…Hydroxyapatite, as a kind of natural material, has been widely used as the bioactive component of polymer material for bioactive implant [4,5]. It had been proved that the addition of HA accelerated the crystallization of PVA hydrogel, and increased the mechanical strength of the PVA-H/HA composite.…”