Many authors have investigated spherical resonators with WGMs. Relatively early investigations from theoretical and experimental views were published in the literatures. Furthermore, transmission characteristics of optical fibers including taper fibers have also investigated theoretically. Hollow glass microspheres were successfully pumped by hollow-glass fiber tapers and showed high-Q factors (quality factors) >109, where the matching between WGMs of hollow glass microspheres and transmission modes of fiber-tapers was inevitable for laser performance.

Nowadays, [fiber tapers]/[hollow-glass spheres] system was well established experimentally in a laboratory scale and theoretical background was understood satisfactory. As pointed out in the literature, however, from the theoretical point of views, hollow glass microspheres and optical coupling devices such as a fiber taper should have nearly equal refractive index for satisfying the mode matching. Moreover, fiber tapers, unclad and unsupported waveguides, are very fragile.

Therefore, if we have plans to open up a way to use the wide possibilities of hollow glass microspheres of various compositions, development of the pumping techniques that is conventional and applicable for commercial uses is an urgent issue. Similarly, tailoring the glass composition is requested for obtaining desirable physical and chemical properties from their wide-spreading properties. Our works on the high-index glass spheres aim at giving one of the answers to the issues: two pumping techniques are applicable to the practical uses and the multicomponent high-index glass is chosen to explore the possibilities. In terrace hollow glass microspheres, for obtaining high resonant emission, refractive index difference between the sphere and the terrace portion (nsphere/nterrace = nr > 1.3) is inevitable.

The pumping experiment of high-index spheres using a half-polisher fiber coupler showed the improvement of optical coupling by high-refractive-index film (nD = 1.73) coating on the polished core. These results were not explained by the above-mentioned theoretical consideration of the [fiber tapers]/[hollow-glass spheres] system. Theoretical support for our new experimental techniques is the next important issue to make advance in practical applications.

This article comes from sciencedirect edit released

Hollow glass microspheres can be used in numerous applications; as an adjusting aid and distancing element of electricity-conducting single components, in microelectronic mechanics, as an abrasion-deterring element in grating components, in mechanical engineering, and as a material for artistic surface design.

A New Adhesive System

The Controltac adhesive system is an innovation in the area of large format graphic films. In this system, approximately 50 µm strong films are equipped. In addition to the adhesive, millions of microscopic (40 up to 50 µm diameter) hollow glass microspheres are utilized in an exact, regular arrangement.

This is achieved through the preceding microstructuring of the surface. The small hollow glass microspheres create a gliding effect between the adhesive and the area to be adhered, enabling precise alignment of the foil.

The spheres sink into the adhesive layer upon application of stronger pressure, and can then be permanently fixed to the base. This technology enables large formatting foils to be adhered.

Lighter Materials

Another, new application comprises of a composite material of metal and hollow glass microspheres. The new material both shines and feels like solid metal, but at the same time, is remarkably light. In order to achieve this, the metal is poured into hollow glass spheres measuring 60 µm.

If the hollow glass microspheres are unevenly distributed, it results in an even surface, which feels completely smooth like metal. With an irregular distribution of the glass, the material appears as if it were marbled with veins.

Although the material is very porous, it appears completely smooth and weighs very little. With the density of aluminum of 2.7 g/cm3 is lowered to 1.2 g/cm3. With zinc from 7 g/cm3, it is reduced by more than half, namely to 3.1 g/cm3.

This article comes from azom edit released

Hollow glass microspheres have great potential in building energy-saving and industrial insulation. Anatase TiO2-modified hollow glass microspheres were prepared by a sol‒gel method in acetic acid-ethanol solution. Scanning electron microscopy, X-ray diffraction, zeta-potential measurements, nitrogen-sorption measurements, and Fourier-transform infrared and ultraviolet-visible-near-infrared diffuse reflectance spectroscopies showed that the alkali modification of the hollow glass microspheres greatly influenced the loading and microstructure of the TiO2 film.

he TiO2 loading could be accurately controlled by ethanol addition and the TiO2 coating time. A mechanism for the TiO2 coating of the hollow glass microspheres surface is proposed. The synergistic action of hydrogen bonding and electrostatic forces resulted in close contact between the hollow glass microspheres and TiO2 sol at pH 3.5.

The effects of different TiO2 loading rates on the reflective and thermal insulation properties were studied. The near-infrared reflectance of 15.9% TiO2 coated on hollow glass microspheres was 96.27%, and the inner surface temperature of the composite pigment coated on aluminum board was reduced by 22.4 °C. The TiO2/hollow glass microspheres composite pigments exhibited excellent solar reflective and thermal insulation properties, so have potential in the construction of exterior walls and roofs.

This article comes from sciencedirect edit released

Uniform spherical-shaped hollow glass microspheres have lower surface area then irregular fillers and extender pigments, which means a lower resin demand. Another benefit to the spherical shape is the ability to roll past one another, hence there is minimal impact on viscosity when they are added to a liquid. As coatings are manufactured on weight basis and sold on volume basis, hollow glass microspheres are used to increase the solid content of a coating, maintaining application and flow properties. Higher-volume solids reduce VOCs, shrinkage and drying time.

Since hollow glass microspheres lower the density of materials, they are added to coatings. If added in coatings, it will atomize better while spraying and it will give less spatter while rolling also sag less once applied.

One of the most important applications hollow glass microspheres have been developed for is the Space Shuttle program. When the space shuttle re-enters the earth’s atmosphere, incredible heat is generated due to increasing air friction. In order to prevent the space shuttle from burning up during re-entry, NASA scientists developed a superior insulating material using Ceramic technology. This technology can now be applied to roofs and sidewalls of buildings, piping, ducts, tanks, various storage devices, refrigerated containers, cold rooms, etc. in order to insulate them from the radiant heat of the sun and the atmosphere by using hollow glass microspheres.

Stagnant air is a bad conductor of heat because heat is transferred by convection currents. Stagnant air inside hollow glass microspheres acts as an insulator for heat and hence can be used as heat insulating material in coatings. This characteristic of hollow glass microspheres allows improved thermal and acoustic insulation properties of coatings or composites. Currently, markets taking advantage of this property include fire retardant materials, sensitive acoustic equipment, and roof coatings.

This article comes from PCI edit released

Hollow Glass Microspheres Market size was USD 1,938.3 million in 2019 and will grow at a CAGR of 4.4% from 2020 to 2026. Rising demand of energy efficient buildings and reducing greenhouse gas emission will positively impact on increase product demand over the forecast timeframe.

Hollow glass microspheres are also known as bubbles, microbubbles and micro-balloons. These are typically made of borosilicate-soda lime and offer various benefits such as low density, chemical resistance and high heat. Glass microspheres walls are quite rigid and have a thickness of over 10% of overall diameter of a sphere.

Based on application, the market is classified into paints & coatings, plastics, composites & rubber, transportation, insulation & buoyancy, healthcare, and others. The industry is likely to witness a high demand in Russia, China, Brazil, and India owing to the growing manufacturing sector and heavy infrastructure spending. Latin America is also forecast to achieve a high growth rate over the forecast period owing flourishing to oil & gas industry in the region, which offer lucrative growth opportunities to the major players of global hollow glass microspheres market.

This article comes from gminsights edit released

Hollow glass microspheres made from water-resistant and chemically-stable soda-lime borosilicate glass, providing better utility in underwater applications. Additionally, they are non-combustible and non-porous, so they do not absorb resin; and their low alkalinity makes this product compatible with most resins while providing a stable viscosity and a long shelf-life.

These low-density particles are used for many demanding applications across a wide range of industries to provide temperature and pressure resistance, reduce part weight, lower costs and enhance overall product properties. For these reasons, hollow glass microspheres are a superior alternative to many conventional fillers and additives such as silica, calcium carbonate, talc and clay.

This article comes from palmerholland edit released

Hollow glass microsphere-reinforced epoxy hollow spheres were prepared by a “rolling ball method” using expanded polystyrene beads, hollow glass microspheres, and epoxy resin. The three-phase epoxy syntactic foam was fabricated by combining hollow glass microsphere as a lightweight filler with EP and hollow glass microsphere by a “molding method”.

The hollow glass microsphere and epoxy curing agent systems were well mixed by scanning electron microscopy. Experiments show that higher hollow glass microsphere stack volume fraction, lower hollow glass microsphere layer number, higher hollow glass microsphere diameter, lower hollow glass microsphere density, higher hollow glass microsphere volume fraction, and lower hollow glass microsphere density result in a decrease in the density of the three-phase epoxy syntactic foam.

However, the above factors have the opposite effect on the compressive strength of the three-phase epoxy syntactic foam. Therefore, in order to obtain the “high-strength and low-density” three-phase epoxy syntactic foam, the influence of various factors should be considered comprehensively to achieve the best balance of compressive strength and density of the three-phase epoxy syntactic foam. This can provide some advice for the preparation of buoyancy materials for deep sea operations.

This article comes from acs edit released

Porous wall hollow glass microspheres were developed by the Savannah River National Laboratory. What makes these microspheres unique is the interconnected porosity spread throughout their wall allowing various materials to travel from the surface to the hollow interior. With their characteristic porosity, the porous wall hollow glass microspheres are a great tool for encapsulating or filtrating different materials. Unfortunately, there is little information available on the mechanical properties of porous wall hollow glass microspheres.

The main goal of this research was to develop a method to crush individual microspheres and statistically analyze the results. One objective towards completing this goal was to measure the microsphere diameter distribution. Microsphere diameter is a major factor affecting strength as well as the Weibull parameters. Two different methods, microscopy counting and laser light scattering, used in the research yielded similar distributions.

The main objective of this research was to analyze the crush strength of individual microspheres. Using nanoindentation, data were collected to analyze the crush strength of porous wall hollow glass microspheres in uniaxial compression. Nanoindentation data were used to analyze how the strength of the porous wall hollow glass microspheres changes through the different stages of production and at different diameter ranges. Data for microspheres were compared to ARC microspheres. Most data were analyzed using a statistical technique known as the two parameter Weibull analysis. The data indicated that the strength generally decreased as the microsphere diameter increased. Scattering in the data was nearly the same across all sample sets tested. Results indicated that the porous wall hollow glass microspheres were weaker than the ARC hollow glass microspheres. This is primarily due to the addition of wall porosity in the porous wall hollow glass microsphere.

This article comes from nmt edit released

Microspheres are small spheres made of various types of materials that are usually less than 100 microns in diameter. These microspheres can be hollow or solid and have been made from a variety of materials including metals, polymers, and ceramics/ glasses.

Hollow glass microspheres have found use in a variety of other applications from defense to transportation to construction. This hollow glass microsphere was unique due to the development of interconnected porosity in the glass wall of the microsphere and is known as a Porous Wall Hollow Glass Microsphere (PWHGM). The addition of pores in the microsphere makes it possible to fill the hollow cavity of the PWHGM with different materials. This development creates many new applications for filtration and encapsulation using PWHGMs. The basic properties of PWHGMs are different compared to other hollow glass microspheres. PWHGMs can have a diameter that ranges from 2 to 100 microns.

PWHGMs have wall thicknesses in the range of approximately 0.5 to 2 microns giving them a diameter to wall thickness ratio range between 4 and 200. By definition thin walled structures have diameter to wall thickness ratios of greater than 10. Unlike many commercial microspheres, such as the soda lime borosilicate ones manufactured, PWHGMs are comprised of around 96% pure silica.

PWHGMs start out as borosilicate HGMs and then are heat treated. Due to their composition, these HGMs undergo spinodal decomposition and phase separate into two interconnecting phases: sodium borate and silica. The sodium borate is leached away with acid leaving mostly porous silica as the wall material. This is how the characteristic nanoporosity of the PWHGMs is created. The wall porosity will generally be 0.01 to 0.1 microns in diameter. Encasing the wall are two layers that are thought to be created during the leaching step. These layers exhibit a different type of porosity than the inner wall porosity.

This article comes from vtechworks edit released

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 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, hollow glass microspheres were incorporated.

Silane treatment of hollow glass microspheres by (3-aminopropyl)triethoxysilane was performed to enhance interfacial adhesion with BM. Adequate wetting of hollow glass microspheres 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.% hollow glass microspheres, and a desirable decrease in density was observed for all the composite samples with increasing content. Improvement in hardness but a marginal decrease in impact strength due to hollow glass microspheres fillers was observed.

Rheological analysis of the composite melt samples showed an apparent increase in the complex modulus with increasing content. Thermal analysis of the composites revealed a significant impact of hybrid fillers on the crystallinity, with SBF showing a minimal effect while hollow glass microspheres reducing it significantly. Wide-angle x-ray diffraction spectra showed changes in the crystal structure of the composite with noticeable β-form peaks.

This article comes from springer edit released