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Bi-doped CaO–Al2O3–SiO2 glass microspheres with Ca2Al2SiO7 (gehlenite) composition were prepared by combination of solid-state reaction and flame synthesis. The concentration of Bi was 0.0, 0.5, 1 and 3 mol%. The chemical composition of prepared glass microspheres was determined by X-ray fluorescence (XRF). The structural and magnetic properties of prepared glass microspheres and their polycrystalline analogues were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy and SQUID magnetometry. The closer inspection of glass microspheres surface by SEM confirmed smooth surface and revealed no features indicating presence of crystalline phases. All Bi-doped microspheres are X-ray amorphous, however in case of undoped microspheres XRD detected traces of crystalline gehlenite. XRD analysis of samples crystallized at 1273 K for 10 h revealed the presence of gehlenite as the main crystalline phase. The presence of gehlenite in crystallized samples were also confirmed by Raman spectroscopy. All samples (glass microspheres and their crystalline analogues) showed diamagnetic or weak ferromagnetic behavior at room temperature, whereas paramagnetic or weak ferromagnetic behavior was observed at 2 K.

Rigid polyurethane foam (RPUF) as a filling material that can enhance the crashworthiness of thin-walled tubes. GO-HGMS hybrid was prepared by solution blending of graphene oxide (GO) and hollow glass microspheres (HGMS). The effect of the composite on the compression properties of RPUF was investigated. The GO-HGMS hybrid was characterized by fourier transform infrared spectroscopy (FTIR), x-ray diffraction(XRD), and scanning electron microscopy (SEM). The compression test and microstructure results show that the best compression performance and the largest apparent density of the composite foam were obtained when the hybrid content was 4 wt %. In addition, the compression test results of empty tubes (ET) and foam-filled tubes (FFT) under lateral load indicate that the combination of lightweight foamed material and thin-walled tube improves the stability of thin-walled tube deformation and the ability of the structure to resist deformation. GO-HGMS/RPUF as the filling material of thin-walled tube structure greatly improves the bearing capacity and energy absorption level of ET.

The results of obtaining hollow glass microspheres and their effect on the properties of water-dispersion facade coatings when the titanium oxide and calcium carbonate in the formula are replaced by an equivalent volumetric number of spheres are presented.

Polyurethane coatings containing copper(II) L-tyrosine and glass microspheres were laser irradiated and underwent electroless metallization. Various sizes of glass microspheres were incorporated into the polyurethane coating matrix in order to examine their effects on surface activation and electroless metallization. The surface of the coatings was activated by using ArF excimer laser emitting ultraviolet radiation (λ = 193 nm) using different number of laser pulses and their fluence. The effects of surface activation and metallization were evaluated mainly based on optical and scanning electron microcopies (SEM), energy-dispersive X-ray spectroscopy (EDX) and photoelectron spectroscopy (XPS). It was found that the presence of glass microspheres enabled the reduction in copper complex content, intensified the ablation process (higher cone-like structures created) and resulted in higher content of copper metallic seeds. On the other hand, the glass microspheres concentration, which was higher for lower size microspheres, was advantageous for obtaining a fully metallized layer.

A technology was developed for producing in a plasma reactor glass microspheres using the ferruginous quartzite tailings of the Kursk Magnetic Anomaly [KMA]. The predictable effects of the plasma-forming argon-gas flow rate and the plasma reactor power on the fractional composition were determined. It is shown that on increasing the plasma-forming gas flow rate from 1.5 to 2.5 m3/h and the current strength from 400 to 500 A the fraction amount over 630 μm increases due to coagulation processes. It is shown that the glass microspheres are enriched in aluminum and calcium oxides and depleted of silicon, magnesium, sodium, potassium, and iron oxides. It is shown that at high plasma temperatures, of the order of 9000 – 12,000 K, the particles melt completely and spherical glass microspheres ranging in size from 80 to 1250 μm are formed. Operational metrics, such as microhardness, acid resistance, and alkali resistance, of the glass microspheres based on the ferruginous quartzite tailings of KMA were investigated.

Glass microspheres with yttria-alumina eutectic composition (76.8 mol% Al2O3 and 23.2 mol% Y2O3) were prepared by sol-gel Pechini method and flame synthesis with or without subsequent milling. Prepared amorphous powders were studied by X-ray powder diffraction (XRD), particle size analysis (PSA), scanning electron microscopy (SEM) and differential thermal analysis (DTA). Hot pressing (HP), rapid hot pressing (RHP) and spark plasma sintering (SPS) were used to sinter amorphous precursor powders at 1600 °C without holding time (0 min). The preparation process including milling step resulted in amorphous powders with narrower particle size distribution and smaller particle size. All applied pressure assisted sintering techniques resulted in dense bulk samples with fine grained microstructure consisting of irregular α-Al2O3 and Y3Al5O12 (YAG) grains. Milling was beneficial in terms of final microstructure refinement and mechanical properties of sintered materials. A material with the Vickers hardness of HV = (17.1 ± 0.3) GPa and indentation fracture resistance of (4.2 ± 0.2) MPa.m1/2 was prepared from the powder milled for 12 h.

Polymeric syntactic foams are composites made from the mixture of Hollow Glass Microspheres (HGM) and polymer matrices. One of their main characteristics is their low density and the production of these composites using a matrix derived from renewable sources potentiates their development without neglecting sustainability. In this paper , the properties of High Density Polyethylene (HDPE)/HGM syntactic foams containing 1% and 5% w/w HGM and 5% w/w of a compatibilizer are assessed. The composites were prepared by two processing routes: single screw extruder and twin screw extruder. The morphology and mechanical properties (tensile and impact) of the syntactic foams thus manufactured were ascertained. Morphological analysis indicated that matrix/filler adhesion was poor for all samples and that the best HGM dispersions were obtained in twin screw extruded samples. Mechanical properties were affected by the processing route adopted and by the content of hollow glass microspheres added. Elastic modulus, tensile strength and strain were reduced by 20, 10 and 23%, respectively, in systems processed in a twin screw extruder. Impact strength was the exception, with an increase of more than 300%. Higher contents of hollow glass microspheres led to reductions in mechanical strength of the syntactic foams, varying from 5% for the elastic modulus to 50% for strain.

Solar steam generation (SSG) as a pollution-free and sustainable way for desalination or wastewater treatment has attracted great attention in recent years. Herein, we report the fabrication of novel aerogels GAHAS and GAHAF composed of 3-aminopropyltriethoxysilane (KH550)-modified hollow glass microspheres (HGM) and reduced graphene oxide (RGO) by a sol-gel method for highly efficient SSG. The RGO can well wrap on modified HGM and form an interpenetrated porous structure with an excellent mechanical property. In addition, benefiting from the hollow structure of HGM, GAHAS obtained by supercritical CO2 drying well maintains the original structure of the hydrogel and shows low thermal conductivity (0.0823 W m-1 K-1) in the wet state and self-floating ability. Combined with its superhydrophilic wettability and high light absorption (ca. 93%), the as-prepared GAHAS shows an outstanding photothermal conversion efficiency of 89.13% under 1 sun (1 kW m-2) illumination and excellent stability. Moreover, from the simulated seawater outdoor solar desalination experiment, it was found that the concentrations of the four primary ions K+, Ca2+, Na+, and Mg2+ in purified water are 1.65, 0.09, 1.42, and 0.32 mg L-1, respectively, and fully meet drinking water standards. Thus, our GAHAS aerogel shows great potential for practical application in SSG. This work enriches the photothermal materials and may provide a new idea for design and creation of HGM-based photothermal materials with low thermal conductivity, tunable porosity, high mechanical strength, self-floating ability, and high solar energy conversion efficiency for SSG.

Present work is focused on the preparation of bulk glass with stoichiometric yttrium aluminium garnet (YAG) composition, which has high tendency to crystallize. Glass microspheres were prepared by flame synthesis from sol-gel prepared YAG precursor. Sintering conditions in SPS apparatus such as heating rate, pressure and temperature were optimized with the aim to prepare transparent material. Results revealed that glass with high tendency to crystallize is very sensitive to time of densification under load (associated with the maximum applied temperature). The increase of the pressure led to the expansion of the translucent part of the sample. Dense, and slightly translucent amorphous samples (total transmission measured at 550 nm was 4.8 %) were successfully prepared by viscous flow SPS sintering of glass microspheres at temperatures below 910 °C without any isothermal dwell.

The physicomechanical and technological properties of polypropylene-based composites filled with basalt fibers (BF) and glass microspheres (GM) are studied. It is shown that the introduction of short BFs and glass microspheres into PPs while ensuring good “fiber-matrix” adhesion by adding maleic anhydride-grafted polypropylene (MAPP) leads to a significant increase in the elastic modulus and tensile yield strength. The impact strength of composites improves with increasing fiber content in the presence of GM. The melt index and thermomechanical stability of the developed composites increase.

In this work, novel composites based on poly(&epsilon, caprolactone) (PCL) were prepared and characterized in terms of morphological, thermal, rheological and mechanical properties. Hollow glass microspheres (HGM), alone or surface modified by treatment with (3-aminopropyl)triethoxysilane (APTES) in order to enhance the compatibility between the inorganic particles and the polymer matrix, were used to obtain lightweight composites with improved properties. The silanization treatment implies a good dispersion of filler particles in the matrix and an enhanced filler&ndash, polymer adhesion. The addition of HGM to PCL has relevant implications on the rheological and mechanical properties enhancing the stiffness of the material. Furthermore, the presence of HGM strongly interferes with the crystallization behavior and thermo-oxidative degradation of PCL. The increase of PCL crystallization rate was observed as a function of the HGM amount in the composites. Finally, rotational molding tests demonstrated the possibility of successfully producing manufactured goods in PCL and PCL-based composites on both a laboratory and industrial scale.

Using the universal software package “Solid Works”, on the example of a cubic model of a composite based on hollow glass microspheres (HGM), numerical simulation of the elastic behavior of a syntactic material under uniaxial tension is carried out. The chosen computational model is a hollow thin-walled glass sphere placed in a polymer (epoxy) matrix of cubic shape. The model was calculated using the finite-element method in an elastic approach with boundary conditions defined by the used universal software system of 3D modeling of the “Solid Works” complex. The calculations made it possible to determine the longitudinal and transverse elastic strains for the model of a syntactic composite with different contents of the initial components and then to calculate the value of the elastic modulus and the Poisson's ratio under tension for these materials. Experimental verification of the calculations performed was carried out on samples of syntactic composites based on epoxy binder and HGM of type MC-ВП A9 2 gr. A size group of microspheres with a diameter of 50 to 70 microns was isolated from the initial HGM by sieving method. The average diameter of these microspheres was about 59 microns. On the basis of the microspheres selected in this way, samples of epoxy composites with different volume contents of components (30%, 40% and 50% HGM) were made and their actual elastic characteristics under tension were measured. The results of experiments to determine the elastic characteristics of syntactic composites correlate well with the calculations, especially for composites with a filling coefficient of 0.45–0.5 with hollow microspheres.

Purpose To evaluate the microsphere flow dynamics and residual yttrium-90 (90Y) activity during and after transarterial radioembolization with glass microspheres and to assess the distribution and predilection sites of residual activity in the administration devices. Materials and Methods In this laboratory investigation, after 18 consecutive clinical transarterial radioembolization and 4 ex vivo experimental procedures with 90Y glass microspheres, the distribution of residual activity in the administration devices was assessed by activimeter and positron emission tomography (PET)/CT measurements. During ex vivo procedures, microsphere outflow from the administration device was assessed by dynamic scintigraphic measurements. Results Mean residual activity was 3.4% ± 1.7 (range, 0.9%–8.8%). Calculations showed a negative correlation between relative residual activity and prescribed activity (r = −0.4258, P = .0486) and a positive correlation between absolute residual activity and prescribed activity (r = 0.5345, P = .0104). The main predilection site was the Luer-Lok microcatheter connector. Lower activities were detected in the dose vial. Flow measurements showed that more than 98% of the final injected activity was transferred to the patient with the first 20 mL of saline solution. Conclusions Residual activity in the standard administration device for glass microsphere radioembolization is considered to be low compared with similar procedures, but is variable. The microsphere flow profile shows an initial peak, resulting in a rapid activity transfer at the beginning of the injection process. The findings may have implications for safe handling of the administration device and for dose calculation of 90Y glass microspheres.

Addition of fillers in polyurethane foams enhances the mechanical properties of polymeric foams. However, fillers can be loaded to a certain extent, as higher percentage of fillers in polymeric foam causes structural instability leading to the collapse of foam. In this article, we report the use of hollow glass microspheres as a possible co-filler which enables higher loading of nano-clay in flexible polyurethane foam. It has been observed that the structural and mechanical properties of nano-clay-loaded foams were found to cause instability at 5 wt% loading of nano-clay. Therefore, upon addition of hollow glass microspheres in 5 wt%, nano-clay-loaded polyurethane foam shows remarkable enhancement in terms of stability and mechanical properties of the resultant foams. A 100-fold increment in tensile strength has been observed for 2 wt% hollow glass microspheres and 5 wt% nano-clay-loaded flexible polyurethane foams as compared to conventional (unloaded) polyurethane foams.

Naphthalene is a toxic aromatic compound whose presence in aqueous environments is very hazardous. In this research, naphthalene removal from wastewater using titanium dioxide-nitrogen-sulfur (TiO2-N-S) photocatalyst immobilized on glass microspheres was investigated. Additionally, the effect of visible and sunlight, radiation time, pH, and initial concentration of naphthalene on photocatalytic removal of naphthalene were studied. Scanning electron microscope images revealed nanoparticles with an average size between 10 and 15 nm, and X-ray diffraction pattern revealed nano-photocatalyst with an average size of 11 nm. Energy-dispersive X-ray showed the presence of two elements, that is, sulfur and nitrogen in the crystalline structure of TiO2 powder, and diffuse reflectance spectroscopy showed the energy bandgap narrowing and transfer of photocatalytic activity of TiO2-N-S to the visible region. Chemical kinetic equation of naphthalene removal was second-order kinetic. The maximum level of naphthalene removal in the presence of visible and sunlight was obtained at a concentration of 25 mg/L (94.29%) and 40 mg/L (93.24%), respectively. Therefore, the immobilized TiO2-N-S on glass microspheres can be used as a new, effective, and functional method in treating water and industrial wastewater containing naphthalene in the presence of visible and sunlight.

Hollow glass microspheres HGM are light, round, hollow, hydrophilic microspheres used to produce polyolefin composites with reduced density. To maintain mechanical strength, it is necessary to improve the adhesion between the polymer matrix and the microspheres, which is done by a compatibilizer. For polypropylene composites a maleic anhydride grafted polypropylene copolymer PP-g-MAH is employed. The melt mixing is done in a reactive extrusion when the maleic group of the compatibilizer reacts with hydroxyl groups present at the microspheres’ surface, grafting a long PP chain. The aim of this work is to quantify the esterification grafting conversion and its efficiency during the reactive extrusion to the formation of PP/HGM composites compatibilized with PP-g-MAH. Techniques like TGA, FTIR and SEM were used to quantify the grafted PP content formed and the efficiency of the esterification reaction, which is mainly dependent of the compatibilizer concentration and reactive extrusion temperature.

Natural fibre reinforced polymer (NFRP) composites are emerging as a viable alternative to metal parts for lightweight components in the automotive and aerospace industry. They are economical and eco-friendly, but their use is confined due to their performance properties. Currently, fillers are often incorporated in NFRP composites to modify their properties. This study explores the reinforcing effects of hollow glass microspheres (HGM) as fillers in continuous NFRP composites. Continuous NFRP laminates were fabricated using woven fabrics (jute, hemp, flax, polypropylene) and HGM with compression moulding. Tensile, flexural and impact tests were conducted to investigate the influence of HGM on the mechanical properties of these laminates. The results indicate that the loading of 1.5 % HGM improves the tensile and flexural properties, but further addition of HGM (3 %) leads to a decline in these properties; furthermore, the impact strength was significantly improved (17 %, 8 %, 24 %) in jute, hemp and flax laminates, respectively by the addition of 3 % HGM.

The article presents experimental results of changes in the dielectric and mechanical characteristics of spheroplastics based on an organosilicon elastomer and metallized glass microspheres caused by static and shock compression. Two regions of the frequency dispersion of the dielectric constant are established that are associated with the metal coating of microspheres. It was found that both the low- and high-frequency dispersions of the complex dielectric constant decrease sharply at a relative compressive strain of no less than 70%. Possible causes of the detected change in the complex permittivity are discussed.

Background Sudan III has been shown to be carcinogenic to human beings due to the azo chemical structure. A simple, highly selective, and environmentally friendly pretreatment method is usually required before the analysis of Sudan III in complex practical samples due to low concentration and matrix interference. Objective The aim of this research was to prepare buoyant adsorbents, octyl trimethoxysilane caped hollow glass microspheres (HGMs), and establish a new pretreatment method for the detection of Sudan III in real samples. Method HGMs were activated and transferred to a flask containing 80 mL ethanol solution (9:1, v/v) and 0.9 mL ammonia. The octyl trimethoxysilane was added to the slurry and covalently coupled on the surface of the HGMs. The modified HGMs were used as adsorbents for the enrichment of Sudan III. After adsorption and desorption, the UV-Vis absorption spectrum was recorded under excitation at 506 nm. Results Under the optimum conditions, the linear range and detection limit were 0.10–4.0 mg/L and 0.048 mg/L, respectively. The proposed method was successfully employed to detect Sudan III in chili products with acceptable recoveries of spikes (90.7–102%). Conclusions The adsorbent, which could be separated by flotation, provided a new solid phase extraction method for the pretreatment of complex samples. Highlights A new solid phase extraction method was provided for the pretreatment of complex samples. In addition, the adsorbents with high enrichment efficiency can be easily separated by flotation and repeatedly used for separation and enrichment of Sudan III.

Transarterial radioembolization (TARE) is, by all standards, a radiation therapy. As such, according to Euratom Directive 2013/59, it should be optimized by a thorough treatment plan based on the distinct evaluation of absorbed dose to the lesions and to the non-tumoural liver (two-compartment dosimetry). Since the dosimetric prediction with 99mTc albumin macro-aggregates (MAA) of non-tumoural liver is much more accurate than the same prediction on lesions, treatment planning should focus on non-tumoural liver rather than on lesion dosimetry. The aim of this study was to determine a safety limit through the analysis of pre-treatment dosimetry with 99mTc-MAA single photon emission computed tomography (SPECT/CT), in order to deliver the maximum tolerable absorbed dose to non-tumoural liver. Data from intermediate/advanced hepato-cellular carcinoma (HCC) patients treated with 90Y glass microspheres were collected in this single-arm retrospective study. Injection was always lobar, even in case of bilobar disease, to avoid treating the whole liver in a single session. A three-level definition of liver decompensation (LD) was introduced, considering toxicity only in cases of liver decompensation requiring medical action (LD type C, LDC). We report LDC rates, receiver operating characteristic (ROC) analysis between LDC and NO LDC absorbed dose distributions, normal tissue complication probability (NTCP) curves and uni- and multivariate analysis of risk factors associated with toxicity. A 6-month timeline was defined as necessary to capture all treatment-related toxicity events. Previous transarterial chemoembolization (TACE), presence or extension of portal vein tumoural thrombosis (PVTT) and tumour pattern (nodular versus infiltrative) were not associated with tolerance to TARE. On the contrary, at the multivariate analysis, the absorbed dose averaged over the whole non-tumoural liver (including the non-injected lobe) was a prognostic indicator correlated with liver decompensation (odds ratio = 4.24). Basal bilirubin > 1.1 mg/dL was a second even more significant risk factor (odds ratio = 6.35). NTCP analysis stratified with this bilirubin cut-off determined a 15% liver decompensation risk at 50 Gy/90 Gy for bilirubin >/

Yttrium aluminate glass microspheres with the eutectic composition 76.8 mol. % Al2O3 and 23.2 mol. % Y2O3 were prepared by combining the sol-gel Pechini method with flame synthesis. The sol-gel method was applied to achieve the desired composition homogeneity of the prepared glass and hence, improve the microstructure homogeneity and mechanical properties of bulk polycrystalline materials. The latter were prepared by hot pressing, more specifically pressure assisted sintering, at 1050 °C, 1300 °C and 1600 °C using pressures of 30 MPa and 80 MPa and holding times between 0 and 30 min. This also led to the crystallization of the glass. A composite with the Vickers hardness 18.0 ± 0.7 GPa and an indentation fracture toughness 4.9 ± 0.3 MPa.m1/2 was obtained by sintering at 1600 °C, at the pressure of 80 MPa and with 30 min isothermal heating at the maximum temperature. Improved mechanical properties were observed when increasing the temperature of sintering and the holding time. This can be attributed to the formation of a unique microstructure consisting of α-Al2O3 grains in the μm-scale embedded in a YAG (yttrium-aluminium garnet) matrix in the hot-pressed samples.

The standard of care for intermediate stage hepatocellular carcinoma is transarterial chemoembolization (TACE). Drug-eluting bead TACE (DEB-TACE) has emerged as a leading form of TACE, as it uses highly calibrated microspheres to deliver consistent embolization and controlled drug release to the tumor microenvironment. We report here on doxorubicin (DOX)-loaded polyphosphate glass microspheres (PGM) as a novel resorbable, radiopaque, preloaded DEB-TACE platform. Coacervate composed of polyphosphate chains complexed with Ba2+ , Ca2+ , and Cu2+ can be loaded with DOX prior to PGM synthesis, with PGM production achieved using a water-in-oil emulsion technique at room temperature yielding highly spherical particles in clinically relevant size fractions. In vitro, DOX release was found to be linear, pH dependent, and in accordance with Type II non-Fickian transport. PGM degradation was characterized by an initial burst release of degradation products over 7 days, followed by a plateau in mass loss at approximately 75% over a period of several weeks. in vitro studies indicate that PGM degradation products, namely Cu2+ , are cytotoxic and may interact with eluted DOX to impair its pharmacological activity. With additional compositional considerations, this approach may prove promising for DEB-TACE applications.

In this work composites based on poly(?-caprolactone) (PCL) were prepared and characterized in terms of morphological, rheological and mechanical properties. Two different fillers were used either individually or in combination: hollow glass microspheres (HGM) to obtain lightweight composites and hemp fibers (HF) to increase the mechanical performances of PCL. Moreover, the effect of HF alkaline treatment on the properties of composites was investigated. On the basis of scanning electron microscopy (SEM) inspections, a good dispersion of fillers in the composites was found, and the alkaline treatment of fibers resulted in an improved filler-matrix adhesion. The addition of either HGM or HF has relevant implications on the rheological and mechanical properties enhancing the stiffness of the composites. In particular, the composites reinforced with both HGM and HF exhibit an increase of Young modulus up to 117% and a reduction of theoretical density of about 10% compared to the neat PCL matrix.

Se utilizó un sistema de espumación compuesto por microesferas de vidrio huecas (HGM) y microesferas térmicamente expandibles (EM) para lograr un equilibrio entre las propiedades seleccionadas de polipropileno (PP) espumado mediante moldeo por inyección, combinando las mayores propiedades de flexión y menor densidad requeridas en las piezas interiores de los automóviles. El L16 de Taguchi (44.23) se empleó para el plan experimental y la relación señal/ruido (S/N) para la optimización del sistema planteado. Los dos parámetros importantes de moldeo por inyección que afectan a las propiedades seleccionadas fueron la temperatura de la masa fundida y del molde. El efecto más importante efecto sobre el módulo de flexión fue la cantidad de HGM, y para la densidad la cantidad de EM., Ministerio de Economía, Industria y Competitividad (project MAT2017-85101-C2-1-R)

Products made of syntactic foams are replacing many conventional materials due to several desirable properties and commendable low density. To overcome its limitation in application it has been hybridized with CNT in this work to achieve multifunctional, mechanical and thermo-mechanical enhanced composites. It is found that when HGM is added to epoxy/CNT matrix compressive strength increases till 5% to a maximum value of 176MPa at 5wt% of HGM and beyond this volume of HGM strength decreases considerably. Storage modulus increases with increase in HGM volume due to increased restriction in polymer chain mobility of epoxy matrix. Microstructure images of fractured surface of the composites evident the good dispersion of HGM and CNT in the epoxy matrix. It can also be seen in SEM images that many microcracks generated are discontinuous and hence increasing the stability of composite in plastic region

Particle filled polymers are used in very large quantities in advance composite materials. Although investigations have done to evaluate the mechanical properties of particle filled composites, Finite Element Analysis (FEA) analysis have not done so for. Therefore, in this work, the elastic modulus of randomly distributed particle filled composite materials are computed by finite element method and verified with the already published experimental data. Spherically shaped solid and hollow glass particles and epoxy are used as fillers and matrix materials respectively. The FEA is applied to a single representative volume element model. The failure theories and mathematical models are verified with the numerical values.

Phosphate-based glasses (PBGs) are biomaterials that degrade under physiological conditions and can be modified to release various ions depending on end applications. This study utilized slow-degrading (P45:45P2O5-16CaO-24MgO-11Na2O10 4Fe2O3, mol %) and comparatively faster degrading (P40:40P2O5-16CaO-24MgO-20Na2O, mol %) PBG microspheres with or without porosity, to evaluate the combined effect of chemical formulation and geometry on human mesenchymal stem cells (MSCs), a clinically relevant cell source for orthopedic applications. Scanning electron microscopy showed 2, 46, and 29% of P45 bulk (P45-B), P40 bulk (P40-B), and P40 porous (P40-P) microspheres, respectively, that had cracks or peeling off surfaces after 42 days of incubation in culture medium. Cytotoxicity assessment showed that glass debris released into the culture medium may interact with cells and affect their survival. Direct-contact cell experiments up to 42 days showed that P45-B microspheres did not sustain viable long-term cell cultures and did not facilitate extracellular matrix formation. On the other hand, P40-B microspheres enhanced alkaline phosphatase activity, calcium deposition, and collagen and osteocalcin production in MSCs. Introduction of porosity in P40 glass further enhanced these parameters and proliferation at later time points. The small pore windows (

Spherical mesoporous bioactive glasses in the silicon dioxide (SiO2)–phosphorus pentoxide (P2O5)–calcium oxide (CaO) system with a high specific surface area of up to 300 m2/g and a medium pore radius of 4 nm were synthesized by using a simple one-pot surfactant-assisted sol–gel synthesis method followed by calcination at 500–700°C. The authors were able to control the particle properties by varying synthesis parameters to achieve microscale powders with spherical morphology and a particle size of around 5–10 μm by employing one structure-directing agent. Due to a high calcium oxide content of 33·6 mol% and a phosphorus pentoxide content of 4·0 mol%, the powder showed very good bioactivity up to 7 d of immersion in simulated body fluid. The resulting microspheres are promising materials for a variety of life science applications, as further processing – for example, granulation – is unnecessary. Microspheres can be applied as materials for powder-based additive manufacturing or in stable suspensions for drug release, in bone cements or fillers.

In this study, poly(acrylonitrile-co-butadiene-co-styrene)/hollow glass microspheres (ABS/HGM) composites were prepared by means of a twin-screw extruder. HGM were incorporated at different loadings of 2.5, 5.0, and 7.5 wt.% at the central extruder zone with different types of ABS. The morphological, physical, thermal, rheological and mechanical properties of ABS/HGM composites were investigated. Statistical analysis reveals that high impact ABS addition is significant for improving composites’ impact strength. The results also indicated that addition of 5.0 wt.% of HGM along with 5.0 wt.% of powdery ABS at the central extruder zone maintains the HGM integrity while powdery ABS contributes to better filler dispersion in the matrix resulting in light-weight composites having improved mechanical properties.

Polyurea was modified by glass microspheres. Compositions of polyurea coatings based on glass microspheres were obtained. The properties of the coatings were evaluated. The results of studies of polyurea-based coating compositions containing hollow glass microspheres are reported. Similar coatings are proposed for waterproofing pre-insulated heat pipes. The composition of a polyurea-based coating containing hollow glass or aluminum-silicate microspheres with diameter 200 – 300 μm and a range of functional additives including ammonium polyphosphate, wollastonite, and microcalcite in a 1 : 1 ratio of glass to aluminum-silicate microspheres was investigated.

Hollow glass microspheres (HGMs) are mainly used as an inert low density filler in polymeric matrices. HGMs made of chemically stable soda-lime-borosilicate glass with high crush-strength allow to attain light weight composites with a reduced resin content. The present work is aimed at obtaining low density polyethylene (LDPE) composites filled with HGMs as suitable light weight material for the manufacturing of plastic items by rotational molding. HGMs were used as such or surface modified by treatment with dodecyl(triethoxy)silane (DDTES), a commercial coupling agent bearing an alkyl chain, in order to enhance compatibility between the inorganic particles and the hydrocarbon polymer matrix. The effectiveness of the silanization process was established using FTIR spectroscopy. LDPE composites at various HGMs content were prepared by melt blending. Morphology of untreated and silane-modified HGMs, their dispersion in the ensuing composites as well as filler/matrix adhesion were investigated by means of SEM microscopy. Uniaxial tensile tests carried out on the composites revealed an increase in the elastic modulus with respect to the neat LDPE and confirmed the good filler/matrix adhesion observed by SEM for the silane-modified HGMs.

Glass microspheres are considered to be suitable fillers in syntactic foams due to their high specific strength, however, it's evidently easy to react with Al-Mg alloy or Mg alloy. A surface protection coating MgO were successfully prepared on microspheres using sol-gel method. The crystallization process and coating effect of MgO with different molar ratio acetic acid complexant in sol compositions were studied. The dried gels were dehydrated and polycondensed to form magnesium acetate and finally turned to be stable MgO after annealing at 400 °C. The MgO coatings, with small particles after annealing, successfully modified the surface of microspheres when the sol composition (molar) magnesium acetate hydrate/acetic acid/dry ethanol was 1:6:29. The MgO coating has inhibited the excessive interfacial reaction between the glass microspheres and the Al-Mg alloy matrix in syntactic foam which the reasons have been discussed.

In this work, of poly(hydroxybutyrate) (PHB) and glass microspheres (HGM) in different compositions with polypropylene-grafted-maleic anhydride (PP-g-MA) composites were developed by melt intercalation, and then, films from the composites and the polymer matrix were obtained. Subsequently, the morphological, thermal, and mechanical properties were evaluated. A good distribution and intermediate dispersion of the filler throughout the matrix with the formation of some agglomerates was observed, while adhesion between the components was not achieved. The HGM did not affect significantly the thermal properties of the systems; there were discrete variations in the initial degradation temperature (Tonset), peak temperature (Tp), and melting temperature (Tm). However, the degree of crystallinity decreased with the addition of the HGM, and the film with 3% HGM had a variation above 11%. Additionally, it was noticed that the composites (regardless of the presence of PP-g-MA) presented small values of elongation and ultimate stress compared with those of pure PHB. Keywords: Polymer composite, PHB, Thin films, Mechanical properties, Thermal properties, Hollow glass microspheres

This research work is carried out to study the mechanical and wear behaviour of inorganic particle filled polymers. The usage of polymers especially epoxy resin is of considerable significance in the engineering field for a substantial period of time. Epoxy matrix filled with varying ratios of Solid glass microspheres (SGM) were fabricated using mechanical stirring process. The weight percentage of SGM were varied from 0 – 30, with a step size of 5wt%. Effect of weight percentage of SGM particles on bending strength, compression strength and compression modulus of the composites was evaluated. The Wear resistance of the composites against En-32 steel disk, was evaluated in terms of mass loss for various ratios of SGM using pin-on-disk test rig. Besides these, density of the composites was also evaluated. Mechanical and wear properties of the composites were improved by adding suitable percentage of the filler. Moreover density increased with the increase in percentage of SGM particles in the composites. Thus, the mechanical and wear properties of the epoxy can be improved by including solid glass microspheres in suitable percentage.

Granulated compounds based on polystyrene with hollow glass microspheres in different proportions were made on a twin-screw extruder. Microspheres were added to polystyrene composition in order to get light-diffusing material with optimal proportion of light transmission and light diffusion properties. The microspheres showed stability due to increased strength in processes. Adding the microspheres led to an increase in the light diffusion factor and to a reduction in the light transmission factor and the material density. The filler gave light diffusion properties to polystyrene in the research doses, whereas the light transmission factor reduced to the acceptable value. The microspheres may be researched additionally for giving light diffusion properties to polymeric materials, used in light engineering.

Mesoporous bioactive glass microspheres (MBGMs) with large mesopores have attracted considerable attention in the field of bone tissue regeneration and drug delivery systems due to their excellent bioactivity, biocompatibility and high specific area. In this study, a loose structure of MBGMs with adjustable chemical compositions was synthesized by the combination of sol-gel and water-in-oil (W/O) microemulsion. All the prepared MBGMs possessed a large mesopore diameter that increased with CaO content, a high surface area and good apatite-inducing formation ability. In vitro protein absorption and release assays demonstrated that the MBGMs exhibited decreased loading efficiency and burst release behavior as the CaO content increased. Additionally, an enhanced BSA-loading amount and prolonged release curve were obtained after the surfaces of MBGMs were modified by amine groups. Furthermore, the preliminary in vitro cell experiments showed that MBGMs exhibited good biocompatibility. The results indicated that MBGMs could be a promising candidate as a drug/protein carrier for bone tissue regeneration.

The infrared stealth fabric was prepared using silver-plated Hollow Glass Microspheres (HGMs) doped with aluminum powder by coating. Silver-plated HGMs was produced by in-situ polymerization of polyaniline (PANI) firstly and followed by electroless silver plating. The surface morphology was characterized by scanning electron microscopy (SEM). FT-IR and XRD analysis were further carried out to verify the preparation of silver-plated HGMs and coated fabrics during the reaction. Thermal infrared imaging device was used to test infrared radiation intensity of coating cotton fabric. Anti-electromagnetic radiation tester was used to evaluate shielding effectiveness. The surface temperature difference of the heated coating fabric was measured. Thermogravimetric (TG) analysis was carried out to study thermal stability. Only a little temperature rises after heating the coating fabric with low infrared radiation, and the shielding effectiveness (SE) can reach 26.8 dB. The results demonstrated this material was endowed with outstanding infrared stealth, electromagnetic interference (EMI) shielding and thermal radiation protection properties.

Roughening of non-conductive substrate ceramic materials with hydrofluoric acid (HF) is usually an essential step to enhance adhesion of the coating by electroless chemical plating. However, the violent reaction between HF and the hollow glass microspheres (HGMs) usually causes breakage and damage of the thin shells of HGMs. This paper proposes a modified roughening strategy for Ni electroless plating, i.e., eroding HGMS slowly with a mixture of sodium fluoride (NaF) and hydrochloric acid (HCl). The Na2SiF6 by-products from the reaction of NaF with SiO2 were erased by the following NaOH washing to expose the surface of HGMs without any obvious pores or breakage. Such a modified roughening and followed alkali washing strategy can thus not only reduce the surface corrosion, but also hinder the further damage of HGMs by covering Na2SiF6 sediments. The successive plating of uniform Ni nanoparticles on HGMs was conducted, and the related mechanism was discussed in detail.

A novel floating visible-light photocatalyst (HGMs–TiO2/Ag3PO4) composite was prepared using amino modified low-density hollow glass microspheres (HGMs) as carriers to disperse and support TiO2 and Ag3PO4 photocatalysts. The surface morphology, crystal structure and optical properties of the HGMs–TiO2/Ag3PO4 composites were characterized and the Ag3PO4 content on the surface of the microspheres was determined by atomic absorption spectrometry (AAS). Methylene blue (MB) was chose as the organic pollutant to investigate the visible-light catalytic properties of the HGMs–TiO2/Ag3PO4 composites. For HGM composite photocatalysts, when the theoretical mass ratio of TiO2 to Ag3PO4 on the surface of HGMs is 1 : 1.5, the visible-light catalytic activity of the composite is superior to pure Ag3PO4 and a TiO2/Ag3PO4 photocatalyst with a mass ratio of 1 : 1.5 under the same conditions, due to the increased light-contact area and the photocatalytic active sites, since the TiO2 and Ag3PO4 particles can be well dispersed on the surface of the floating HGMs. Furthermore, the deposits of TiO2 and Ag3PO4 on the HGM surface form a heterostructure, facilitating the separation of electron–hole (e− – h+) in the energy band, and elevating the photocatalytic activity and cycle stability of Ag3PO4. This work indicates that floating HGMs–TiO2/Ag3PO4 composites could become a promising photocatalyst for organic dye removal due to the low cost and high visible-light responsiveness.

Innovative composites based on polyethylene (PE) filled with hollow glass microspheres (HGMs) were formulated and successfully prepared as suitable plastic materials for rotational molding technology. The HGMs here used allow to attain lightweight materials with a reduced resin content and appealing aesthetical qualities. To enhance filler dispersion and phase adhesion, thus improving the ultimate properties of the composite materials, two compatibilization strategies were adopted: namely, surface modification of HGMs by dodecyl(triethoxy)silane or addition during mixing of a maleinized PE as in-situ coupling agent. The effectiveness of the surface treatments on HGMs was assessed by attenuated total reflectance Fourier-transform infrared spectroscopy and thermogravimetric analysis investigations. PE-based composites at various HGMs contents (5, 10, and 20 wt%) were prepared by melt blending. Morphology of untreated and modified HGMs, their dispersion in the composites as well as filler/matrix adhesion were investigated by SEM microscopy. Thermal, rheological and mechanical properties of the composites were studied in comparison with neat PE. Rotational molding tests carried out both in laboratory and industrial site demonstrated the feasibility of producing lightweight plastic items (weight reduction up to 17%) of excellent aesthetics on a large scale.

Light-weight and high-strength polymer composites have attracted the special attention of automotive and aerospace sectors since they offer advantages such as less fuel consumption and higher fuel efficiency. In the present study, an effort has been made to prepare such polymer composites using natural fiber and very low-density hollow inorganic particles. The use of hollow glass microspheres (HGM) as a potential filler particle for making light-weight hybrid polymer composites was investigated. Polypropylene (PP) and maleic anhydride-grafted-polypropylene (in 9:1 ratio) constituted the base matrix (BM). For strength reinforcement, alkali-treated short bamboo fibers (SBF) were employed, while for making the composite material light in weight, HGM were incorporated. Silane treatment of HGM by (3-aminopropyl)triethoxysilane was performed to enhance interfacial adhesion with BM. Adequate wetting of HGM and SBF was evident from the SEM images of cryo-fractured samples. A 14% increase in tensile strength was observed in comparison to virgin PP for the composite with 5 wt.% HGM, and a desirable decrease in density was observed for all the composite samples with increasing HGM content. Improvement in hardness but a marginal decrease in impact strength due to HGM fillers was observed. Rheological analysis of the composite melt samples showed an apparent increase in the complex modulus with increasing HGM content. Thermal analysis of the composites revealed a significant impact of hybrid fillers on the crystallinity, with SBF showing a minimal effect while HGM reducing it significantly. Wide-angle x-ray diffraction spectra showed changes in the crystal structure of the composite with noticeable β-form peaks.

Current trends in regenerative medicine treatments for bone repair applications focus on cell-based therapies. These aim to deliver the treatment via a minimally invasive injection to reduce patient trauma and to improve efficacy. This paper describes the injectability of porous calcium phosphate glass microspheres to be used for bone repair based on their formulation, rheology and flow behavior. The use of excipients (xanthan gum, methyl cellulose and carboxyl methyl cellulose) were investigated to improve flow performance. Based on our results, the flow characteristics of the glass microsphere pastes vary according to particle size, surface area, and solid to liquid ratio, as well as the concentration of viscosity modifiers used. The optimal flow characteristics of calcium phosphate glass microsphere pastes was found to contain 40 mg/mL of xanthan gum which increased viscosity whilst providing elastic properties (∼29,000 Pa) at shear rates that mirror the injection process and the resting period post injection, preventing the glass microspheres from both damage and dispersion. It was established that a base formulation must contain 1 g of glass microspheres (60–125 μm in size) per 1 mL of cell culture media, or 0.48 g of glass microspheres of sizes between 125 and 200 μm. Furthermore, the glass microsphere formulations with xanthan gum were readily injectable via a syringe-needle system (3–20 mL, 18G and 14G needles), and have the potential to be utilized as a cell (or other biologics) delivery vehicle for bone regeneration applications.

The structural and magnetic properties of undoped and Ni-doped aluminate glass microspheres with gehlenite (Ca2Al2SiO7) composition and of their polycrystalline analogues were studied. The concentration of Ni was 0.0, 0.5 and 3.0 mol. %. Glass microspheres were prepared by combination of solid-state reaction and flame synthesis. The detailed examination of morphology of the glass microspheres of all prepared composition by scanning electron microscopy (SEM) revealed no features indicating presence of crystalline phases. X-ray powder diffraction (XRD) confirmed amorphous character of prepared Ni-doped gehlenite glass microspheres. In samples crystallized at 1273 K for 10 h, XRD revealed the presence of gehlenite as the main crystalline phase. Raman spectroscopy of crystallized samples also confirmed the presence of gehlenite. Raman spectra of as-prepared glass microspheres differed significantly from the spectra of their crystallized counterparts. These indicate the role of aluminum as a network-forming element. Magnetic properties of the Ni-doped gehlenite microspheres and of their polycrystalline analogues were measured by SQUID magnetometer. Properties of the measured samples showed a more complex magnetic behaviour. Diamagnetic, paramagnetic and ferromagnetic components can be observed depending on whether Ni-doping is used or not, as well as depending on temperature and applied magnetic field values, both for glass microspheres and crystalline samples.

Light scattering composites based on polystyrene, polyethylene and glass hollow microspheres have been developed. Composites with the optimal ratio of light transmission and light scattering coefficients has been produced.