Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/6963
Title: Measurements of heat treatment effects on bovine cortical bones by Nanoindentation and compression testing
Authors: Lau, ML
Lau, KTA 
Ku, H
Bahattacharyya, D
Yao, YD
Keywords: Bone
Heat treatment
Nanoindentation
Mechanical properties
BSE
EDX
Issue Date: Jan-2012
Publisher: Scientific Research
Source: Journal of biomaterials and nanobiotechnology, Jan 2012, v. 3, no. 1, p.105-113 How to cite?
Journal: Journal of biomaterials and nanobiotechnology 
Abstract: Heat treatment of bone is one of the reliable and simple sterilization methods to overcome the risk of rejection and disease transfer from allograft and xenograft, in particular for the prevention of human immunodeficiency virus (HIV) infection. However, the mechanical property of the micro-structural level after heat treatment is not well characterized. To address this issue, this study was carried out to compare the localized mechanical properties of micro-structural tissue with those at the global structural level. Nanoindentation technique has been well accepted as an accurate technique to measure mechanical property of small and heterogeneous specimen nondestructively, as well as the complex bio-material of micro-structural level, often with a resolution of better than 1 μm. In this study, nanoindentation was conducted to measure the localised elastic modulus and hardness values of bones at temperature of 23℃ (room temperature – non-heated sample), 90℃ and 150℃, respectively. All experiments were conducted at room temperature (~23℃). The elastic modulus (E) and nanoindentation hardenss (H) values in the longitudinal direction of bones heated at 150℃ were recorded as 23.43 GPa and 0.73 GPa, respectively; as in transverse direction, the E and H values were 12.77 GPa and 0.54 GPa, respectively. It showed significant increases of 44% and 43% in the longitudinal direction as compared to those of the non heat-treated bones. In addition, E and H values in transverse direction also showed increases of 23% and 38%, respectively as compared to those of the non heat-treated bones. Furthermore, heat-treated bones at 90℃ in longitudinal direction also appeared to have significant increases of 18% and 31% in E and H values, respectively. However, the E and H values in transverse direction increase only by 0.4% and 12.8%, respectively. In addition, compressive test is employed to measure the global stiffness (E) of the bone samples. When heated at 150℃, the bone specimen showed an increase of 60% in stiffness (E) and an increase of 26% in yield stress. On the other hand, when heated at 90℃, a slight increase of 11.4% in stiffness (E) and 21.5% in yield stress were recorded respectively. Furthermore, energy dispersive X-ray spectroscopy (EDX) which integrated with Backscattered Electron (BSE) imaging was conducted to examine the relationship between mineral content and mechanical strength within the nanoindentation regions. The data demonstrated that the non heat-treated bones obtained the highest calcium wt% amongst the three groups; as temperature increased, there was a slight decrease in calcium wt%; however, the changes were not severe in this study.
URI: http://hdl.handle.net/10397/6963
ISSN: 2158-7027 (print)
2158-7043 (online)
DOI: 10.4236/jbnb.2012.31014
Rights: Copyright © 2012 SciRes.
This is an open access article distributed under the Creative Commons License.
The article: Lau, M. L., Lau, K. T., Ku, H., Bahattacharyya, D., & Yao, Y. D. (2012). Measurements of heat treatment effects on bovine cortical bones by nanoindentation and compression testing. Journal of Biomaterials and Nanobiotechnology, 3(1), 105-113 is available at http://dx.doi.org/10.4236/jbnb.2012.31014
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