Effect of plasticizer on production of bioactive synthetic calcium phosphates/glass composites and their properties

Bioactive synthetic calcium phosphates/glass composites have been produced using PVA as a plasticizer (0, 10, 15, 20 mass%). Changes in the linear, volumetric and weight parameters of samples upon sintering at 800 °C as well as in the density, porosity and compression strength have been investigated. It was established that all of the ceramics studied (both produced with and without PVA) exhibit a linear (0.7-1.9%) and volumetric (2.3-4.9%) shrinkage, which increases with using PVA and raising its content. The microstructure examination of samples obtained with a plasticizer revealed a complex porous morphology and the presence of complex-shaped 10-50 µm pores. An increase in PVA amount led to transformation of a flake-like structure and formation of particles of regular rounded shape. The pycnometric density did not depend on using PVA and equaled 2.58-2.61 g/cm3. PVA promoted an increase in the total porosity from 24.7 to 35.8% and a decrease in the density by 1.66 to 1.89%. Porosity increased proportionally to the amount of introduced PVA and was the highest for composites produced with 20 mass% addition of PVA. Open porosity dominated in all of the composites with PVA addition. The ultimate compression strength was in the range 42-93 MPa and reduced with increasing PVA amount.