Electrical conductivity of polycrystalline hydroxyapatite and its application to electret formation

Horiuchi, Naohiro; Madokoro, Kazuki; Nozaki, Kosuke; Nakamura, Miho; Katayama, Keiichi; Nagai, Akiko; Yamashita, Kimihiro

doi:10.1016/j.ssi.2017.11.029

Cited by 41 publications

(35 citation statements)

References 42 publications

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“…Further, the conductivity of Cl‐NBR/Cl‐EPDM/HA composites is higher than the unfilled blend and the conductivity increases with the loading of nanoparticles. In comparison with the bare blend system, the incorporation of crystalline nano HA powder imparts a well‐defined compact structure (as evident from XRD) and the more uniform dipolar polarizations derived from the orientation changes of OH − ions in the HA crystals distributed in the nanocomposites significantly improves conductivity 34 . The composite with 7 phr HA powder shows maximum conductivity; further loading of nanoparticles decreases the magnitude of hopping of charge carriers.…”

Section: Resultsmentioning

confidence: 99%

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Nihmath

Ramesan

2020

J of Applied Polymer Sci

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Hydroxyapatite nanoparticles (HA) reinforced polymer blend based on chlorinated nitrile rubber (Cl‐NBR) and chlorinated ethylene propylene diene monomer rubber (Cl‐EPDM) were prepared. Resulting blend composites were analyzed with regard to their rheometric processing, crystallinity, glass transition temperature (Tg), mechanical properties, oil resistance, AC conductivity, and transport behavior. The decrease in optimum cure time with the addition of HA is more advantageous for the development of products from these blend nanocomposites. The XRD, FTIR, and SEM confirmed the attachment and uniform dispersion of HA nanoparticles in the Cl‐NBR/Cl‐EPDM blend. The good compatibility between polymer blend and nanoparticles was also deduced by the formation of spherically shaped HA particles in the blend matrix determined by TEM analysis. DSC analysis showed an increase in Tg of the blend with the filler loading. The addition of HA particles to the blend produced a remarkable increase in tensile and tear strength, hardness, AC conductivity, abrasion, and oil resistance. The diffusion of blend composites was decreased with an increase in penetrant size. The diffusion mechanism was found to follow an anomalous trend. Among the blend composites, the sample with 7 phr of HA not only showed good oil and solvent resistance but also a remarkable increase in AC conductivity and mechanical properties.

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Section: Resultsmentioning

confidence: 99%

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Nihmath

Ramesan

2020

J of Applied Polymer Sci

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“…64 r is a parameter that depends largely on density/porosity, microstructure, grain size, and to a large extent, on the processing parameters and conditions. 80 Also, the sintering temperature is kept at 1073 K, which is not very high in comparison to the traditional ceramics that are fired at >1273 K. The FESEM micrographs too revealed the fact that a considerable amount of pores are retained in the ST specimens and those that contained a higher amount of ST. A similar value of r at 1 MHz is also reported by Wong et al, 81 where no dispersion in the behavior of r , is reported in the probed frequency domain. In Figure 6B, the variation of r with frequency is plotted.…”

Section: F I G U R E 4 Field Emission Scanning Electron Microscopy Grain Size Estimation and Eds Of (A) St (B) Hap (C) 80h-20s And (D) 20mentioning

confidence: 99%

Physical, chemical, and biological investigations of composites for biomedical applications

et al. 2021

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In this article, the interplay between structural, electrical, and surface properties in determining the collective behavior of Ca 10 (PO 4 ) 6 (OH) 2 (hydroxyapatite, HAP) and SrTiO 3 (strontium titanate, ST) composites was reported. The monoliths HAP and ST were synthesized using sol-gel and solid-state reaction, respectively, and were mixed in different atomic concentrations (20,40,60, and 80 at.%) to prepare a series of composites. The prepared composites were then subjected to x-ray diffraction (XRD) and Raman analysis for probing the microstructural aspects. The analysis revealed no evidence of a phase that the reaction between the two monoliths might form. The crystallite sizes were in the range of 27.2-37.3 nm, and it increased with the content of ST in the composites. The Raman analysis revealed the presence of rutile TiO 2 that was later found to be the link in the display of bone-like apatite nucleation ability in the monolith ST and its composites. The FESEM analysis revealed that the grain sizes were 64-144 nm between the monoliths and were found to follow a similar trend to the crystallite size. The dielectric constant ( r ) varied with temperature ranging from 5 to 35 (1 MHz) at 310 K for all the specimens. The dependence of r on the grain size of the composites followed a nearly exponential relation. The bone-like apatite forming ability of the composites was studied by incubating the specimens in simulated body fluid (SBF). Additionally, the cytocompatibility (MG63 cell lines) and protein adsorption (bovine serum albumin [BSA]) of the selected specimens were also studied to comprehensively understand the delicate relationship between the electrical and biological properties. The protein adsorption was primarily related to the surface charge, and its dependence was found to be linear. Additionally, the r of the composites was ≤35, which compliments the protein adsorption behavior of the specimens.The amount of adsorbed protein for all the specimens considered in this study was in the range of 3-32 μ g/ml. Furthermore, the specimens exhibited excellent cell viability of more than 90%. Based on the physical and biological investigations, 20H-80S was established as the best specimen that blends the characteristic feature of both the monoliths. Finally, the TEM and STEM mapping of the best specimen, projecting the suitability of 20H-80S in the design of electrically active scaffolds and possibly bioelectrets for biomedical applications, was also studied.

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“…The co-doping in HAp leads to the creation of many defects and alters the ionic polarization with respect to electric field. For instance, iron and zinc ions were co-doped in HAp at various concentrations (0.01, 0.05, [35] with permission from Elsevier) and (C) The real part of relative permittivity as a function of frequency for (a) Pristine, (b) 1HAp (1×10 15 ions/cm 2 ), (c) 2HAp (1×10 16 ions/cm 2 ) and (d) 3HAp (1×10 17 ions/cm 2 ) (reproduced from [84] with permission from Elsevier). and 0.1 M) by ultrasonication.…”

Section: Electrical Propertiesmentioning

confidence: 99%

“…Dielectric properties of chlorinated ethylene propylene diene monomer/hydroxyapatite nanocomposites were robustly distorted at lower frequencies whereas above 103 Hz, it was frequency independent [16]. Horiuchi et al reported that the polycrystalline HAp possesses conductive grains and insulating grain boundaries further, interfacial polarization was confirmed to be an electret [17]. In the case of chitosan/HAp composite, the concentration of chitosan plays a predominant role in regulating its hardness, conductivity and dielectric constant [18].…”

Section: Introductionmentioning

confidence: 99%

Impact of Dopants on the Electrical and Optical Properties of Hydroxyapatite

Arul¹,

Ramya²,

Kalkura³

2020

Biomaterials

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This chapter deals with the effect of alternating electrical current on hydroxyapatite [HAp, Ca10(PO4)6(OH)2] and doped HAp along with their optical response and the processes involved. The dielectric constant, permittivity and ac conductivity were analyzed to have an insight into the surface charge polarization phenomenon. Further, the magnitude and the polarity of the surface charges, microstructure, and phases also play significant role in the cell proliferation and growth on the implants. Besides, the mechanism behind the electrical properties and the healing of bone fracture are discussed. The influence of various dopants on the optical properties of HAp viz., absorbance, transmission, band gaps and defects energy levels are analyzed along with the photoluminescence and excitation independent emission. In the future outlook, the analysis of effect of doping is summarized and its impact on the next generation biomaterials are elucidated.

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Electrical conductivity of polycrystalline hydroxyapatite and its application to electret formation

Cited by 41 publications

References 42 publications

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Physical, chemical, and biological investigations of composites for biomedical applications

Impact of Dopants on the Electrical and Optical Properties of Hydroxyapatite

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