Synthesis and Additive Manufacturing of Hydroxyapatite Bone Scaffold Derived from Chicken Bones Calcined at 900°C

Ang, Xun Thern (2023) Synthesis and Additive Manufacturing of Hydroxyapatite Bone Scaffold Derived from Chicken Bones Calcined at 900°C. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Biomaterial is the synthetic or natural material that is used to support or replace any damaged tissue or organ in the human body. Hydroxyapatite (HAp) with chemical formula of Ca10(PO4)6 (OH)2 has received the greatest attention as compared to other bioceramics due to its high similarity in chemical composition with the human bones and teeth that have inorganic phase of Ca5 (PO4)3 (OH). HAp is commonly used in biomedical applications such as bone scaffold and coating on metallic implants. The HAp available in the market is mostly chemically synthesized where chemically synthesised HAp is expensive, complex, and has low bioactivity due to the lack of trace elements. It employs time-consuming manufacturing methods and produces unwanted by-products as well. There are up to 1.3 billion tonnes of food wasted every year and it may cause environmental issue such as global warming. The aim of the study is to synthesise the Hap powder from the chicken bones calcined at 900 °C, fabricate the human bone scaffold by using 3D printing technique of fused deposition modelling (FDM), and to investigate the effect of ball milling time and sintering temperature on the densification of the 3D-printed scaffold. In this research, the pre-treatment of chicken bones was first carried out. The chicken bones were then calcinated at 900 °C. The calcined chicken bones were crushed and sieved to obtain particle size of 106 μm. The HAp powder was ball milled for 1, 2, and 3 hours. The LDPE, paraffin wax and stearic acid was used as the binder in this research. The bone scaffolds were 3D printed by using the FDM technique. The printed bone scaffolds then underwent solvent and thermal debinding stage. Lastly, the debinded bone scaffolds were sintered at 1200°C and 1250°C. The chicken bone that calcined at 900°C achieved high yield percentage of 63.396%. The apparent density, relative density and shrinkage of HAp bone scaffold that sintered at 1200°C are always lower than bone scaffold that sintered at 1250°C. This is due to the porosity of the bone scaffold decreases when the sintering temperature increases. The sintered bone scaffold can always achieve higher apparent and relative density than the green bone scaffold. The apparent density, relative density and shrinkage of bone scaffold increases when the ball milling time of HAp powder increases. This is due to the porosity of bone scaffold decreases when the ball milling time of HAp powder increases. However, the apparent and relative density of green bone scaffold decreases when the ball milling time of HAp powder increases. The highest 3D printing accuracy and quality can be achieved when the nozzle temperature is 145°C and the bed temperature for the first and other layers is 90 and 85°C respectively. The optimum extrusion multiplier for the 3D printing of Hap bone scaffold was found to be 1.8. It is also found that the 3D printing accuracy in x and y-axis increases and the 3D printing accuracy in z-axis decreases when the ball milling time of Hap powder increases.