Biphasic calcium phosphate (BCP) macroporous scaffold with different ratios of HA/β-TCP by combination of gel casting and polymer sponge methods

Abstract

Open and interconnected porous scaffolds were prepared with various ratios of hydroxyapatite (HA)/β-tricalcium phosphate by a combination of gel casting and polymer sponge methods to improve the mechanical properties and structure. The scaffolds were prepared using slurries containing 50 vol.-% of ceramic powders and sintered at 1100°C for 2 h. Thermogravimetric analysis result shows that the proper temperature to burn out organic materials and polyurethane foams is 600°C. The compressive strength was between 5·3 and 8·4 MPa. Field emission scanning electron microscope shows an open, relatively uniform and large interconnected porous structure with pore size ranging between 150 and 400 μm. X-ray diffraction and Brunauer–Emmett–Teller methods were employed to determine the microstructural crystallite and surface area respectively. The results show that the compressive strength of scaffolds increased with the increase in HA concentration. The reason can be explained by the increasing pore wall thickness and density in scaffolds.     

Supported Ziegler type catalysts for production of polyethylene (PE): Effect of the composition of the active component,the methods of its formation,and the use of modifying agents on catalytic activity and molecular structure of PE and copolymers of ethylene with α-olefins

Summarized results are presented from studying the formation of the active component of supported Ziegler type catalysts, investigating the effect of the composition of these catalysts on the molecular mass characteristics of PE, and seeking new methods for producing catalysts with optimum morphology.