Preparation, characterization and some properties of gypsum plaster / calcium phosphate composites as a bone cement
Reham Nagi Emam Saleh;
Abstract
The present work aimed to prepare hydroxyapatite powder by wet precipitation method which was sintered at different temperatures to be blended with plaster for the formation of composites. To achieve this goal hydroxyapatite was prepared by the reaction of freshly prepared calcium hydroxide and phosphoric acid as sources of calcium and phosphorous within the ratio of 1.67at pHs 10, 10.3, 10.7 and 11.The powder was fully characterized using IR, XRD and TEM methods. For the formation of hydroxyapatite–plaster composites, hydroxyapatite was added on gypsum plaster with different amounts to study the effect ofhydroxyapatite addition on the properties of the formed composites. For each ratio of HAp, different L/P ratios were determined and characterized by IR, XRD and SEM and thephysico-mechanical properties of these composites were followed.
The infrared spectroscopic analysis revealed that the first indication for the formation of hydroxyapatite was the broad band appeared at 1100-1000 cm-1due to the phosphate group whilecarbonate group appeared at about 1420 and 870 cm-1for powders prepared at allpH values. Broadness of the bands, characteristic for phosphate groups as the pH increased from 10 to 11 gave an indication for the choice of the pH =11 as the suitable pH for the formation of hydroxyapatite. The appearance of carbonategroup showed that the prepared hydroxyapatite was similar to biological apatite. The XRD analysis of the synthesized powders proved that the obtained powders are composed ofsingle phase of hydroxyapatite and all peaks were indexed for the formation of hydroxyapatite (HAp, Ca10(PO4)6OH2) crystals.It was found that the powder prepared at pH 11 was the most identical with the ASTM card of HAp. Both XRD and IR analysis proved that pH 11 was the suitable pH for the formation of HAp powders.
The TEM investigation showed that the powders prepared at pH11 have nanosized –rod like particles with a length ranged between 20to 40 nm.The formation of nano-sized powder was agood sign that the formed HAp crystals have very loose crystal-to crystal bonds. Therefore, the resorption by osteoclasts was quite homogeneous and hence a higher bioactivity was expected to be obtained.
The properties of synthesized HApfired at temperatures ranged from 1000 up to 1250ºC were investigated.
The infrared spectroscopic analysis displayed for all sintered samples revealed the disappearance of carbonate band in all sintered samples. The band at 1100-1040 cm-1 assigned to HApbecame broad up to 1200 °C and then decreased while the band referred to OH increased in its intensity up to 1200°C and then decreased at 1250°C. Decreasing of these bands at 1250°Cwas attributed to disorder of the structure ofHAp.
XRD analysis proved that up to 1250ºC noother phases were present other than HAp. Increasing the crystallinity at 1250°C is due to lattice disorder.
From the results of bulk densities and apparent porosities at those different temperatures, it was found that the apparent porosity decreases and the bulk density increases with increasing the sintering temperature. Also the change in both properties was abrupt on increasing the sintering temperature from 1000 to 1100°C then became mild smooth up to 1250°C. The abrupt change in the apparent porosities and bulk densities of the sintered bodies was a result of solid-solid densification of the particles and initiation of forming sintered HAp bodies. The decreased rate of apparent porosities and bulk densities on heating over 1150°C may suggest a phase transformation which hindered and minimized the densification rate of the HApas a result of the initiation ofdeformation of hydroxyapatite structure.
The SEM investigations showed that the equiaxial shape of the grains was due to the high surface energy stored in HApnano-rods induced the morphology change from the cylindrical shape as obtained in TEM to equiaxialgrains as indicated from SEM features.
Moreover, the addition of commercial HAp with different ratios on gypsum plaster to form composites gave high compressive strength. Normal consistency of plaster composites were determined and according to the amount of mixing water, plaster composites containing 10, 20 and 30 % porous HAp had been formed. The XRD analyses of these composited, revealed that all peaks were characterized to gypsum and HAp and on other phases were present.
The infrared spectroscopic analysis revealed that the first indication for the formation of hydroxyapatite was the broad band appeared at 1100-1000 cm-1due to the phosphate group whilecarbonate group appeared at about 1420 and 870 cm-1for powders prepared at allpH values. Broadness of the bands, characteristic for phosphate groups as the pH increased from 10 to 11 gave an indication for the choice of the pH =11 as the suitable pH for the formation of hydroxyapatite. The appearance of carbonategroup showed that the prepared hydroxyapatite was similar to biological apatite. The XRD analysis of the synthesized powders proved that the obtained powders are composed ofsingle phase of hydroxyapatite and all peaks were indexed for the formation of hydroxyapatite (HAp, Ca10(PO4)6OH2) crystals.It was found that the powder prepared at pH 11 was the most identical with the ASTM card of HAp. Both XRD and IR analysis proved that pH 11 was the suitable pH for the formation of HAp powders.
The TEM investigation showed that the powders prepared at pH11 have nanosized –rod like particles with a length ranged between 20to 40 nm.The formation of nano-sized powder was agood sign that the formed HAp crystals have very loose crystal-to crystal bonds. Therefore, the resorption by osteoclasts was quite homogeneous and hence a higher bioactivity was expected to be obtained.
The properties of synthesized HApfired at temperatures ranged from 1000 up to 1250ºC were investigated.
The infrared spectroscopic analysis displayed for all sintered samples revealed the disappearance of carbonate band in all sintered samples. The band at 1100-1040 cm-1 assigned to HApbecame broad up to 1200 °C and then decreased while the band referred to OH increased in its intensity up to 1200°C and then decreased at 1250°C. Decreasing of these bands at 1250°Cwas attributed to disorder of the structure ofHAp.
XRD analysis proved that up to 1250ºC noother phases were present other than HAp. Increasing the crystallinity at 1250°C is due to lattice disorder.
From the results of bulk densities and apparent porosities at those different temperatures, it was found that the apparent porosity decreases and the bulk density increases with increasing the sintering temperature. Also the change in both properties was abrupt on increasing the sintering temperature from 1000 to 1100°C then became mild smooth up to 1250°C. The abrupt change in the apparent porosities and bulk densities of the sintered bodies was a result of solid-solid densification of the particles and initiation of forming sintered HAp bodies. The decreased rate of apparent porosities and bulk densities on heating over 1150°C may suggest a phase transformation which hindered and minimized the densification rate of the HApas a result of the initiation ofdeformation of hydroxyapatite structure.
The SEM investigations showed that the equiaxial shape of the grains was due to the high surface energy stored in HApnano-rods induced the morphology change from the cylindrical shape as obtained in TEM to equiaxialgrains as indicated from SEM features.
Moreover, the addition of commercial HAp with different ratios on gypsum plaster to form composites gave high compressive strength. Normal consistency of plaster composites were determined and according to the amount of mixing water, plaster composites containing 10, 20 and 30 % porous HAp had been formed. The XRD analyses of these composited, revealed that all peaks were characterized to gypsum and HAp and on other phases were present.
Other data
| Title | Preparation, characterization and some properties of gypsum plaster / calcium phosphate composites as a bone cement | Other Titles | تحضير وتوصيف ودراسة بعض الخواص لمتوالفات فوسفات الكالسيوم مع الجبس كأسمنت | Authors | Reham Nagi Emam Saleh | Issue Date | 2015 |
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