Effect of temperature and pressure of hot pressing on the mechanical properties of PP–HA bio-composites

This paper focuses on the effects of pressure and temperature in hot press molding on the mechanical properties of polypropylene–hydroxyapatite composites with two different types of silanated and unsilanated hydroxyapatites. Density, crystallinity, ultimate tensile strength, Young’s modulus, and impact resistance were evaluated for the two types of composites. Increasing pressure caused enhancement of density, crystallinity, MFI, ultimate tensile strength, and Young’s modulus. Increases in temperature increased MFI, ultimate tensile strength, and Young’s modulus whilst decreased impact resistance of composites. Effects of increasing pressure and temperature on the mechanical properties of polypropylene–silanated hydroxyapatite were less than their effects on the mechanical properties of polypropylene–unsilanated hydroxyapatite. Micrographs showed changes in fracture mode from ductile to brittle with increasing pressure and temperature during hot press molding.