Model
Digital Document
Publisher
Florida Atlantic University
Description
Hydroxyapatite (HAp) is an ideal bioactive material that is used in orthopedics.
Chemical composition and crystal structure properties of HAp are similar to the natural
bone hence it promotes bone growth. However, its mechanical properties of synthetic
HAp are not sufficient for major load-bearing bone replacement.
The potential of improving the mechanical properties of synthetic hydroxyapatite
(HAp) by incorporating carboxyl functionalized single walled carbon nanotubes
(CfSWCNT) and polymerized ɛ-caprolactam (nylon) is studied. The fracture toughness,
tensile strength, Young’s modulus, stiffness and fracture energy were studied for a series
of HAp samples with CfSWCNT concentrations varying from 0 to 1.5 wt. % without, and
with nylon addition. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM),
Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC)
were used to characterize the samples. The fracture toughness and tensile test was
performed under the standard protocol of ASTM D5045 and ASTM D638-02a respectively. Reproducible maximum values of (3.60 ± 0.3) MPa.m1/2 for fracture
toughness and 65.38 MPa for tensile strength were measured for samples containing 1 wt.
% CfSWCNT and nylon. The Young’s modulus, stiffness and fracture energy of the
samples are 10.65 GPa, 1482.12 N/mm, and 644 J/m2 respectively. These values are
comparable to those of the cortical bone. Further increase of the CfSWCNT content
results to a decreased fracture toughness and tensile strength and formation of a
secondary phase.
Chemical composition and crystal structure properties of HAp are similar to the natural
bone hence it promotes bone growth. However, its mechanical properties of synthetic
HAp are not sufficient for major load-bearing bone replacement.
The potential of improving the mechanical properties of synthetic hydroxyapatite
(HAp) by incorporating carboxyl functionalized single walled carbon nanotubes
(CfSWCNT) and polymerized ɛ-caprolactam (nylon) is studied. The fracture toughness,
tensile strength, Young’s modulus, stiffness and fracture energy were studied for a series
of HAp samples with CfSWCNT concentrations varying from 0 to 1.5 wt. % without, and
with nylon addition. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM),
Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC)
were used to characterize the samples. The fracture toughness and tensile test was
performed under the standard protocol of ASTM D5045 and ASTM D638-02a respectively. Reproducible maximum values of (3.60 ± 0.3) MPa.m1/2 for fracture
toughness and 65.38 MPa for tensile strength were measured for samples containing 1 wt.
% CfSWCNT and nylon. The Young’s modulus, stiffness and fracture energy of the
samples are 10.65 GPa, 1482.12 N/mm, and 644 J/m2 respectively. These values are
comparable to those of the cortical bone. Further increase of the CfSWCNT content
results to a decreased fracture toughness and tensile strength and formation of a
secondary phase.
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