An Investigation into the Structure and Properties of CaO-ZnO-SiO 2-TiO2-Na2O Bioactive Glass/hydroxyapatite Composite

Effect of the addition of CaO-ZnO-SiO2-TiO2-Na2O glass as a reinforcing phase on properties of hydroxyapatite/glass composites was investigated. The addition of the glass caused the decomposition of HA phase to tricalcium phosphate, inhibiting densification in the HA/glass composites. However, depending on the glass concentration, some of the glass can act as a sintering aid enhancing the densification in the composites. © 2013 IEEE

Investigating the Effect of SiO2-TiO2-CaO-Na 2O-ZnO Bioactive Glass Doped Hydroxyapatite: Characterisation and Structural Evaluation

The effects of increasing bioactive glass additions, SiO2-TiO2-CaO-Na2O-ZnO up to 25 wt% in increments of 5 wt%, on the physical and mechanical properties of hydroxyapatite (HA) sintered at 900, 1000, 1100 and 1200°C for 2 h was investigated. Increasing both the glass content and the temperature resulted in increased HA decomposition. This resulted in the formation of a number of bioactive phases. However the presence of the liquidus glass phase did not result in increased densification levels. At 1000 and 1100°C the additions of 5 wt% glass resulted in a decrease in density which never recovered with increasing glass content. At 1200°C a cyclic pattern resulted from increasing glass content. There was no direct relationship between strength and density with all samples experiencing no change or a decrease in strength with increasing glass content. Weibull statistics displayed no pattern with increasing glass content. © 2014 Springer Science+Business Media

Leucaena–Derived Biochar for Biodiesel Production

Giant leucaena wood was utilized to prepare heterogeneous catalysts through a fast pyrolysis method and chemical activation for transesterification. The obtained catalysts were investigated using SEM, CHNS/O analyzer, XRF and XRD. The influence of the concentration of KOH (3-9 M), catalyst amount (0.25-2.0 g), methanol to oil ratio (4:1-10:1), and reaction time (30-75 min) on FAME yield was also studied on transesterification reaction carried out at 60ºC under a 750 rpm stirring speed. The experiment results demonstrate that chemical activation was required to improve the porosity of the catalyst. The result showed that a well-developed porous structure was observed, as the concentration of KOH increased activated biochar become more porous. 7M-KOH for chemical activation was the best condition to obtain a porous catalyst. It was found that the main factors affecting the FAME yield were dependent on various parameters including methanol: oil ratio, catalyst loading, reaction time and stirring speed via transesterification process. The highest yield of 94.06% was achieved on 0.5g of the catalyst activated by 7M-KOH, a methanol:oil ratio of 6:1 and a 1-hour reaction. The obtained biodiesel mainly composed of different fatty acid in follow order C18:1 > C16:0 > C18:2 > C18:0. Properties reached the ASTM D6751-12 and EN 14214:2012 standard, indicating that leucaena-derived biochar is potentially utilized in biodiesel production

Processing and mechanical testing of strontium-substituted hydroxyapatite/glass composites

Sr-HA/Glass composites were produced. Phase composition of composites was evaluated. Their physical and mechanical properties were determined. Sintered composites mainly consisted of Sr-HA/β-TCP, or β-TCP/Ca2ZnSi2O7. The composites had porosity up to 4 times those of undoped Sr-HA. Compared to undoped Sr-HA, the Sr-HA/Glass composites had lower biaxial flexural strength and hardness. The Weibull modulus for the composites ranged from 2.77 to 18.74

Effects of strontium substitution on bioactivity of hydroxyapatite

Effect of strontium (Sr) substitution on bioactivity of hydroxyapatite (HA) was investigated. The substitution of Sr2+ for Ca2+ in the HA lattice increases biodegradability of Sr-substituted HA (Sr-HA) and accelerates the formation of apatite crystals on the Sr-HA surface. Moreover, the dissolution products from HA and Sr-HA samples are not cyto-toxic

Investigating the Addition of SiO2-CaO-ZnO-Na2O-TiO2 Bioactive Glass to Hydroxyapatite: Characterization, Mechanical Properties and Bioactivity

Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560° with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability

Effect of a BaO-CuO-Bi2O3-B2O3 glass flux, and its processing on the dielectric properties of BaTiO3

A seriesofBaTiO3 along withvarious flux oxideshasbeensinteredstep-wiselytoyieldalowsinteringtemperature flux glasscomposition. The developedglass flux (Ba-Cu-Bi-Bsystem)wasaddedtoBaTiO3 with differentamount,andeventuallyyieldedalowsinteringtemperatureof BaTiO3 at 900 1C with7wt% flux glassaddition.Toinvestigatetheinfluence ofprocessingmethods,a flux glassshell-BaTiO3 core structure was developedbyusingseparateballmillingscheduleofglassandbariumtitanatepowders.Comparisonofresultantdielectricpropertieswas made amongdifferentprocessingmethods,andthis flux shellprocessingmethodsnotablymodifies thedielectricpropertiesofsinteredsamples comparing toconventionalprocessingmethods.Thesubsequentstructuralinformation,morphology,andphasestabilityofsinteredsampleswere investigated byInfraredspectroscopy,X-rayphotoelectronspectroscopy(XPS),scanningelectronmicroscopy(SEM)andX-raydiffraction (XRD) respectively.93wt%BaTiO3-7 wt%glasswiththe flux shellstructuredisplayedaninhibitedcubicphasegraingrowth,andareduced tetragonality associatedwithCudopingwasconfirmed byX-raydiffraction.Ahighdielectricconstant(43000) aswellasalowlossyfactor (o0.03) ofthisparticularseriesofsamplewasreported.X-rayphotoelectronspectroscopyshowedthatbridgingoxygenspeciesdecreaseswith increasing Ndaddition,indicatingthattheNdbondstotheglassnetworkasanetworkmodifier insteadofbeingdopedintoBaTiO3 lattice through the flux shell.Thus,weconcludedthattheglass flux shellplaystheroleofsinteringadditive,Cudopingion(containedinglass)carrier, and Ndaliendopantblock

Investigating the addition of SiO2–CaO–ZnO–Na2O–TiO2 bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity

Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560° with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability