Effects of injection moulding process parameters on impact strength of polypropylene-hydroxyapatite biocomposite

Abstract

The present work investigates the impact strength of Polypropylene-Hydroxyapatite (PPHA) biocomposite for orthopaedic scaffold implants and tissue engineering applications. The effects of injection pressure and speed and cooling time on the impact strength of polypropylene (PP) – hydroxyapatite (HA) were studied for a wide range of process parameters using injection moulding machine. PP (100 wt%) was processed using injection moulding machine with optimal process settings. Later, PP (99 wt%) with HA (1wt%) was melt-mixed using a twin-screw compounding extruder followed by injection moulding process to prepare the impact test specimens with varying process parameters. The impact of strength test was conducted according to ASTM-D 256 standards on PP and PP-HA biocomposites. The fractured samples were studied for morphological properties using scanning electron microscope. The result shows that injection moulding parameters had a great influence on their impact strength and morphological properties. The best conditions to produce composites of optimum mechanical properties are injection pressure of 30 MPa, injection speed of 15 cc/s and cooling time of 20 s for PPHA biocomposite. It is known that characterising efficient solutions is an important way to realise the potential of an injection moulding operation. Besides that, by applying all various parameters, we are most definitely able to reduce the time of a real-time injection moulding operation and produce a better quality product.

Keywords

• polypropylene
• hydroxyapatite
• injection moulding
• impact strength