Low temperature formation of calcium-deficient hydroxyapatite-PLA/PLGA composites

Date

2000-09-15

Author

Durucan, Caner

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

128
views

0
downloads

Hydroxyapatite-biodegradable polymer composites have been formed by a low temperature chemical route. Precomposite structures were prepared by combining alpha-Ca-3(PO4)(2) (alpha-tricalcium phosphate or alpha-TCP) with poly(L-lactic) acid and poly(DL-lactide-co-glycolide) copolymers. The final composite structure was achieved by in situ hydrolysis of alpha-TCP to Ca-9(HPO4)(PO4)(5)OH (calcium deficient hydroxyapatite or CDHAp) either in solvent cast or pressed precomposites. Hydrolysis was performed at 56 degrees C-a temperature slightly above the glass transition of the polymers. The effects of polymer chemistry, composite formation technique, and porosity on hydrolysis kinetics and degree of transformation were examined with isothermal calorimetry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and scanning electron microscopy. Calorimetric data and XRD analyses revealed that hydrolysis reactions were inhibited in the presence of the polymers. Isothermal calorimetry indicated the extent of the alpha-TCP to CDHAp transformation in 24 h to be 85% in the solvent cast composites containing PLGA (85:15) copolymer; however, XRD analyses suggested almost complete reaction. The CDHAp formation extent was 26% for the pressed composites containing the same polymer. In the presence of NaCl as a pore generator, 81% transformation was observed for the pressed composites. This transformation occurred without any chemical reaction between the polymer-inorganic components, as determined by Fourier transform infrared spectroscopy. Minimal transformation to CDHAp occurred in composites containing poly(L-lactic) acid. (C) 2000 John Wiley & Sons,Inc.

Subject Keywords

Calcium-deficient hydroxyapatite, Alpha-tricalcium phosphate hydrolysis, Biodegradable polymer, Polylactic acid, Poly(lactide-co-glycolide)

URI

https://hdl.handle.net/11511/55084

Journal

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH

Collections

Department of Metallurgical and Materials Engineering, Article

Suggestions

OpenMETU
Core

Calcium-deficient hydroxyapatite-PLGA composites: Mechanical and microstructural investigation Durucan, Caner (2000-09-15) The microstructural and mechanical properties of composites composed of calcium deficient hydroxyapatite (CDHAp) and poly(lactide-co-glycolide) (PLGA) have been investigated. The composites were formed by hydyolysis of alpha-tricalcium phosphate (alpha-TCP) to CDHAp in pressed precomposite compacts of alpha-TCP-PLGA-NaCl. The differences in hydrolysis of alpha-TCP-PLGA-NaCl for two compositions of 80:10:10 wt % and 60:20:20 wt %. were monitored by isothermal calorimetry and X-ray diffraction. The microstruc...
Pressure dependence of the Raman frequency of an optical mode in cubic gaughe nitrogen Yurtseven, Hasan Hamit (null; 2015-09-18) Solid nitrogen exhibits various phases under different temperatures and pressures. At very high pressures up to about 100 GPa, the most stable structure in nitrogen is the cubic gauche structure and the polymeric crystalline phase is obtained from this structure. In this study, we calculate the Raman frequency of an optical mode (600 cm-1 at P=0) as a function of pressure for cubic gauche nitrogen using some thermodynamic data from the literature. The calculated Raman frequency of this optical mode increase...
Low temperature thermoluminescence behaviour of Y2O3 nanoparticles Delice, S.; IŞIK, MEHMET; Hasanlı, Nızamı (2019-01-01) Y2O3 nanoparticles were investigated using low temperature thermoluminescence (TL) experiments. TL glow curve recorded at constant heating rate of 0.4 K/s exhibits seven peaks around 19, 62, 91, 115, 162, 196 and 215 K. Activation energies and characteristics of traps responsible for observed curves were revealed under the light of results of initial rise analyses and T-max-T-stop experimental methods. Analyses of TL curves obtained at different stopping temperatures resulted in presence of one quasi-contin...
High temperature corrosion of steels used in petroleum refinery heaters Sultan, Abdelrahman; Karakaya, İshak; Department of Metallurgical and Materials Engineering (2005) The oxidation of three different steels used in the construction of petroleum refineryheaters was investigated by using thermogravimetric analysis technique (TGA). C-5,P-11, and P-22 steel samples were tested in two different oxidizing environments; air and CO2+N2+H2O (that simulates the combustion products of natural gas) at two different temperatures; 450oC and 500oC. In air oxidation P-22 had the best oxidation resistance among the three steels at two temperatures. In CO2+N2+H2O environment,C-5 possessed...
High Temperature Mechanical Properties of Ceramic Dispersoid Reinforced 17-4 PH Stainless Steel Produced by Selective Laser Melting Özsoy, Andaç; Dericioğlu, Arcan Fehmi; Aydoğan Güngör, Eda; Department of Metallurgical and Materials Engineering (2021-9-08) Selective Laser Melting (SLM) is a metal additive manufacturing process used to produce complex-shaped parts by the fusion of metal powders by a laser heat source. SLM processing of metals offers various advantages such as freedom of design, part consolidation, fast prototyping, weight reduction etc. Stainless steels have been one of the first choices to be implemented in SLM processing. Among these, 17-4 PH stainless steel holds a sweet spot with its corrosion resistance, weldability and high strength at e...

Citation Formats

C. Durucan, “Low temperature formation of calcium-deficient hydroxyapatite-PLA/PLGA composites,” JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, pp. 717–725, 2000, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/55084.