OPTIMIZATION OF POLYMER TOUGHENING PROCESS OF SOLID HYDROXYAPATITE IMPLANT

The experimental work of this study was conducted using a statistical experimental design in conjunction with the Taguchi method for optimization. The most effective factors affecting the toughening of the ceramic pellets were evaluated. The target of this experimental work was to maximize the product strength and minimize the amount of deposited polymer on the product. The Taguchi signal-to-noise (S/N) ratio was used for the optimization process. The experiments were divided into three stages. Stage One was identifying the parameters and the determination of the range of values to be explored; this step is usually done through literature review and simple experiments. Stage Two was the screening experiments (process characterization) to find out the most significant parameters effects on the process; this stage is done through the design of an orthogonal array based on the number of the input factors into the process. Stage Three was the optimization process itself [1-10]. Stages One and Two were reported in a previous study [9]. Stage Three is the subject of this study; for this stage the levels of the candidate factors were narrowed for more precise optimization. Four candidate factors with three levels were tried using an L9 (34) orthogonal array. The results were optimized using a statistical experimental design using the analysis of means and orthogonal array. The excess polymer removal technique used and the number of polymer solution coatings showed major effects on the flexural strength. Presumably, because these affect the mass of polymer applied. Optimum values of the flexural strength and mass of polymer were determined using statistical experimental design and the Taguchi method. Using the optimum experimental condition for preparing samples produces high quality in dense implants with 10.49 MPa flexural strength and 80 μm thickness of the deposited polymer, with mass of 21.0 mg / sample.