Injection Moulding of HAp for Biomedical Applications

Palm stearin (PSr) or known as vegetable fat has been introduced in injection moulding processes which has great potential as an alternative binder in a binder system.This study presents the processing of Hydroxyapatite (Ca10(PO4)6(OH)2) mixed with 100 vol.% of single based binder palm stearin (PSr) using CIM. The main objective of the research was to determine the optimum formulation of powder-binder mixture via mixing torque and rheological analysis. The process generally started with the selected commercial HAp powder and the binder in correct proportions. From the CPVP test, the critical loading was 70.64%, thus the formulation was formulated below 2-5 vol.% critical loadings. Four different volume fractions of the powder were investigated: 62, 64, 66, and 68 vol.%. During the rheological test, the feedstock containing the mixture and the binder exhibited pseudoplastic properties, which was lower than200 Pa.s with function of shear rate.The injection moulding process was successfully carried out in the injection temperature range of 65°C to 70°C which corresponded to 300 kPa to 400 kPa injection pressure being applied and followed the ASTM C1424-10.