The composite materials using polyhydroxybutyrate as matrix and hydroxyapatite as reinforcement (PHB/HA) were produced by molding, using pressing at 100 MPa and 165 °C for 30 min. The amount of filler was varied from 0 to 20 wt% to evaluate the effect of the HA particles on mechanical properties and the bioactivity of the composites. The increase of the HA amount reduced the compressive strength of the composites nearly 20% while bending strength reduced nearly 30%. However, the bioactivity after 14 days immersion in SBF was improved with the increase of HA amount, with formation of apatite layer on the surface of the PHB/HA composite. Keywords: polyhydroxybutyrate, hydroxyapatite, composite, biomaterials.
Resumo
Materiais compósitos com matriz de poli-hidroxibutirato e material de reforço de hidroxiapatita (PHB
Hydroxyapatite (HA) is a ceramic material broadly studied due to its great similarity with the human bone. However, this material presents high stiffness and young modulus in comparison with the bone tissue. The polyhydroxybutyrate (PHB) is a themoplatic and biodegradable polymer that presents bone like young modulus and gradative degradation that results in a permanence of the mechanical properties after implantation. The aim of this study is to evaluate the effect of the infiltration of melted PHB on the mechanical properties of porose HA bodies. The composite samples were characterized by SEM, EDS and compressive strength. The samples produced with 10% paraffin and sintered at 1200 °C showed the best mechanical properties and reached an increase of the compressive strength from 29,00 ± 4,70 MPa before infiltration to 83,00 MPa ± 4,41 after infiltration with PHB for a final porosity of 5%.
Porous bodies were produced using hydroxyapatite as a starting material, gypsum, high purity material, low cost and that can be molded into the desired shape. Also, beads of polystyrene polymer. The first step of this work was to produce porous gypsum blocks obtained by mixing gypsum, water and polystyrene. After drying, they were submerged in acetone solvent for solubilizing the polymer and pore formation. The porous hydroxyapatite was synthesized in a second stage, where the porous gypsum blocks were immersed in a solution of (NH4)2HPO4 0.5 mol L-1 to 100 ° C and pH 7.0-9.0 for 24 hours. From this method, it was possible to produce bodies single phase hydroxyapatite with a maximum porosity of 70 ± 3% and a compressive strength of 1.48 ± 0.17 MPa.
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