Incorporation of poly(Vinyl alcohol) for the improved properties of hydrothermal derived calcium phosphate cements

Calcium phosphate cement (CPC) has been synthesized via a straightforward hydrothermal route. Calcium oxide and ammonium dihydrogen phosphate were used as calcium and phosphate precursors. The precursors were refluxed in distilled water at 90–100 °C and dried overnight until the calcium phosphate powder was formed. CPC was then produced by mixing the powder and distilled water at the powder-to-liquid (P/L) ratio of 1.5. Poly(vinyl alcohol) (PVA) of 1 to 7% (w/w) was added and its effect on physical properties was investigated. It was proved that PVA addition up to 7% (w/w) has shortened the setting time but decreased the injectability. The PVA free CPC has the initial and final setting times of 71 and 187 min, respectively and the injectability of 99.92%. The compressive strength also increased with the amount of PVA added in CPC. In addition, soaking CPC in Ringer's solution for 7, 14 and 21 days also gave remarkable effects on cohesion, microstructure and mechanical properties of the cement

Calcium phosphate /poly (ethylene glycol) bone cement: cell culture performance

Calcium phosphate cement (CPC) for injectable bone cement application has been developed in this study. The CPC was produced using a novel wet chemical precipitation method derived hydroxyapatite (HA) powder. The calcium and phosphorus precursors used to synthesize HA powder were calcium hydroxide, Ca(OH)2 , and di-ammonium hydrogen phosphate, (NH4 )2HPO4 . The HA powder was mixed with distilled water at certain powder-to-liquid (P/L) ratios. In this study, the P/L ratios were varied at 1.3 and 1.7. PEG was added into CPC with the P/L ratio of 1.3, and it was adjusted at 1 and 5 wt%. The results of this study revealed that higher P/L ratio contributed to the decreased in porosity of CPC. Meanwhile, the addition of PEG increased the porosity of CPC. This is significant for cells adhesion and proliferation, such that cell proliferate faster and better adhesion with the incorporation of PEG into CPC. The cell culture on CPC has proven that the fabricated CPC shows no toxic reaction and cells grow well

Kimia Polimer

xxi+669 hal.; 23C

Characteristic features of plasma electrolytic treated layers in Na3PO4 solution

Plasma electrolytic oxidation (PEO) treatment of Ti6Al4V (Ti) using various concentrations of Na3PO4 (NAP) has been carried out. Based on the PEO process, characteristics of the treated layers, such as structure, chemical composition, phases, roughness, hardness and porosity level were investigated. Irregular micro-channel spots were found on all treated surfaces. Larger pores were more evident on the PEO treated with NAP-7.5 g/L, and are considered to be related to the high intensity of micro-arc discharges on Ti surface. XRD analyses revealed that the surfaces of treated layers are composed of Ti, TiO6 and anatase. The Profilometry test depicted that the surface roughness of PEO treated layers is significantly higher than bare Ti. The thickness and hardness of PEO-treated layers increased with increasing NAP concentration and found to be highest with sample processed with NAP-10 g/L. Among all the NAP concentration used, 5 g/L showed the least level of porosity. Reflection on the results portends that the PEO treated with 10 g/L concentrations could serve a potential candidate for clinical purposes

Recent development of calcium phosphate based coating on titanium alloy implants

Titanium alloy implants are widely employed in biomedical devices and components, especially as hard tissue replacements as well as orthopaedic applications, owing to their favourable properties such as high-strength to weight ratio, low density, low Young’s modulus and biocompatibility. However, metallic implants cannot meet all of the clinical requirements. Therefore, in order to increase their clinical success and long term stability in the physiological environment, surface modification is often performed. This review focuses on the latest achievements in the field of surface modification techniques including sol-gel, thermal spray, magnetron sputtering, electrophoretic deposition and micro-arc oxidation of biocompatible calcium phosphates (CaP) based ceramics coatings for metallic implants with emphasis on the structure, morphological characterization, phase transformation and coating composition. A reflection on the results shows that CaP coatings can be grown with the each type of techniques and a stronger fixation can be enhanced with CaP fabrication on metallic implants. Advantages and limitations of the aforementioned techniques of CaP-based coatings from the point of view of the process simplicity as well as the most important challenges of each coating techniques are highlighted. Further, the most promising method for CaP deposition was identified and a specific area for improvement was discussed

Synthesis of TiO2 nanosized powder photocatalyst via soft-gel method for bacteria inactivation application

Titanium dioxide (TiO2) is the most widely used photocatalyst and has been applied for water and air purification and disinfection of microorganism. Anatase structured TiO2 is a wide bandgap (3.2 eV) semiconductor which, under UV light, is able to degrade chemicals and cell components of microorganisms. In this study, TiO2 nanopowder photocatalyst was synthesized by sol-gel process using a titanium chelate compound, titanium (di-isopropoxide) bis(acetylacetonate) (PTP) as the precursor. The precursor was hydrolyzed under an acidic catalyst condition, followed by reflux for 15 minutes and 1 hour. The precipitate powder obtained after filtration was calcined at 400°C. XRD analysis confirmed that the TiO2 powders A (15 minutes reflux) and B (1 hour reflux) have strongest peak at 25° which indicates anatase crystal structure. The particle size of powder A was smaller than the Powder B as proved by calculation using Scherrer’s equation. The crystallization temperature of TiO2 powder A was higher due to its smaller particles that needed more heat to crystallize than powder B as confirmed by TG/DTA. FESEM analysis showed powder A have homogenous spherical shape, contrast to powder B showing inhomogenous spherical shape and connected particle. The TiO2 photocatalyst activity in killing bacteria was investigated for 5 hours by varying the concentration of TiO2 and UV light intensity

Miscibility, morphology and mechanical properties of compatibilized polylactic acid/thermoplastic polyurethane blends

Polylactic acid (PLA) is a biodegradable polymer and has an excellent strength, however its inherent brittleness and low impact resistance has limited its application. One of the potential alternatives for enhancing the weakness of PLA is by blending it with thermoplastic polyurethane (TPU) which possesses several attractive properties such as high toughness, durability and flexibility. Nevertheless, few works have been reported on the effect of compatibilizer on physical properties of PLA/TPU blends. In this work, the effect of ethylene-methyl acrylateglycidyl methacrylate (EMA-GMA) compatibilizer addition in various blend compositions on miscibility, morphological development and mechanical properties of PLA/TPU blends was analysed. The blends were prepared through melt blending technique and analysis of miscibility and morphological development were conducted using dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM), while evaluation of mechanical properties were performed through tensile and impact tests. Inclusion of EMA-GMA improved miscibility of PLA/TPU blends by reducing the size of the droplets and uniformly dispersed the droplets throughout the matrix. Addition of EMA-GMA further improved mechanical properties of PLA which is showed by significant increment of elongation at break and impact strength of PLA/TPU blends with some composition exhibited non-break behaviour

Effects of sintering time and temperature to the characteristics of FeCrAl powder compacts formed at elevated temperature

This paper presents the outcomes of an experimental investigation on the effect of sintering schedule, i.e., holding time and temperature to the final properties of FeCrAl powder compacts prepared through uniaxial die compaction process at above room temperature. The feedstock was prepared by mechanically mixing iron powder ASC 100.29 with chromium (22 wt%) and aluminium (11 wt%) for 30 min at room temperature. A cylindrical shape die was filled with the powder mass and heated for one hour for uniform heating of the die assembly together with the powder mass. Once the temperature reached to the setup temperature, i.e., 150ºC, the powder mass was formed by applying an axial pressure of 425 MPa simultaneously from upward and downward directions. The as-pressed green compacts were then cooled to room temperature and subsequently sintered in argon gas fired furnace at a rate of 5ºC/min for three different holding times, i.e., 30, 60, and 90 min at three different sintering temperatures, i.e., 800, 900, and 1000ºC. The sintered samples were characterized for their density, electrical resistivity, bending strength, and microstructure. The results revealed that the sample sintered at 1000ºC for 90 min achieved the better characteristics

Physicochemical characteristics of magnesium hydroxyapatite (MgHA) derived via wet precipitation method

Hydroxyapatite (HA) has been known for so many decades as an implant material for medical applications due to its chemical composition that is very similar to the inorganic component of human bone. However, synthetic HA possesses relatively low mechanical strength characteristic, making it less suitable to be used in load bearing applications. Thus, the presence of metal ion like magnesium (Mg) is expected to improve the properties of synthetic HA as biomedical devices. The main objective of this research is to develop and characterize the magnesium hydroxyapatite (MgHA) nanopowders derived from the wet precipitation method. The amount of Mg, which acts as a metallic dopant in HA were varied at 0, 5 and 10% and calcined at 700C for imperative comparison. The resultant nanopowders were then characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) to examine their physicochemical properties. Morphological evaluation by FESEM showed that the particle size of 10% MgHA powders was larger and spherical in shape but still highly agglomerated at calcination temperature of 700C. This result coincides with the data obtained from the XRD analysis, which revealed that the particle size of pure HA, 5 and 10% MgHA after calcination was 87 nm, 98 nm and 116 nm, respectively. These results demonstrate that doping Mg into HA has caused an increase in the particle size, proving that Mg acts as a sintering additive during the calcination process