Porous-wall hollow glass microspheres are a one-of-the-kind material with many potential uses in security technology.

This work focuses on the development of security inks containing porous-wall hollow glass microspheres, whereby the microspheres serve as storage vessels for a variety of functional materials.

This preliminary work comprises two feasibility studies. One study resulted in the successful aerosol jet deposition of hollow glass microspheres onto a substrate. The other study resulted in the loading of porous-wall hollow glass microspheres with gold nanoparticles. Both studies demonstrate the feasibility of developing and delivering a security ink utilizing porous-wall hollow glass microspheres that are loaded with functional materials. The results encourage the continuation of research to achieve this goal.

This article comes from researchgate edit released

In recent years, composite materials containing hollow glass or ceramic microspheres have attracted considerable attention. These materials have very good heat-insulation characteristics, which are largely defined by special features of absorption and scattering of thermal radiation by thin-walled hollow particles (German and Grinchuk, 2002; Dombrovsky, 2005). The paint coatings containing hollow glass microspheres have already found applications for reducing heat loss from the walls of buildings owing to a decrease in thermal radiation at night.

Infrared radiative properties of a polymer containing hollow glass microspheres are studied by means of the measurements of direc- tional-hemispherical reflectance and transmittance in the wavelength range from 2.6 to 18 lm. The measurements are performed for sev- eral samples containing different series of microspheres of volume fraction from about 6% to 66%.

Relatively strong peak of reflectance at the wavelength 4.5 lm was observed. This peak is explained in terms of theoretical model based on Mie theory calculations for single microspheres and modified two-flux approximation proposed recently by the authors. The reflectance of the composite material in the important range from 8.5 to 13.5 lm is determined mainly by rough surface layer of microspheres and it does not described by the model for semi-transparent media. The conditions of a considerable decrease in radiative heat losses from the buildings due to paint coatings containing hollow glass microspheres are discussed.

This article comes from researchgate edit released

Hollow glass microspheres with through-holes at micron level were fabricated by etching them using diluted 1% hydrofluoric acid (HF) solution in a specially designed reaction system.

In this study, the function of each component in the system was carefully investigated and improved to realise the controllable etching process. Various parameters were investigated to explore the optimal etching condition. Highest gross yield of about 85% and effective yield of about 50% were obtained at the optimised etching condition. A separating method was proposed to separate the etched hollow glass microspheres with different hole sizes with the help of reduced pressure.

After separation, hollow glass microspheres with hole size at sub-micron level, less than 10 µm, and bigger than 10 µm, were achieved. The well-etched hollow glass microspheres can be used as universal containers to store both reactive and inactive chemicals for applications in self-healing materials, biochemical engineering, and energy industry.

This article comes from ncbi edit released

The class of hollow glass microspheres selected for a masterbatch depends on the end use of the TPO component. For example, the pressures involved in TPO molding require hollow glass microspheres with elevated crush strength. Hollow glass microspheres strength is generally proportional to density, and thus lower-strength bubbles are less dense, and offer greater potential for TPO weight reduction than thicker-walled, higher-strength bubbles.

Hollow glass microspheres size impacts TPO surface finish as well as stress transmission through the composite, with smaller bubbles contributing to more favorable impact and tensile properties. In general, higher-strength bubbles are required for injected molded interior and exterior automotive components, and other industrial components.

The modulus (stiffness) of a part also increases in proportion to the ratio of hollow glass microspheres to resin. The positive attributes of increased stiffness and heat distortion temperature (HDT) as well as decreasing coefficient of linear thermal expansion (CLTE), shrink, warp, and sink marks continue to improve as the percentage of hollow glass microspheres in the resin mix rises. Tensile strength, elongation, and impact strength tend to decrease as well. Complementary additives in the masterbatch can modify these values to some degree.

In general, plastics are flexible and experience ductile failure under stress, while glass adds stiffness but is more prone to brittle breakage, It is possible to improve TPO impact strength by adding an impact modifier to the masterbatch that reduces potential for brittle failure while maintaining the stiffness advantage.

The concentration of hollow glass microspheres in a masterbatch additive mix varies, but can be as much as 50% by weight, depending on customer requirements. Finished parts made using this masterbatch hollow glass microsphere concentration will be 20% or more lighter than resin-only parts.

Process tests show that a Noble masterbatch formulation with hollow glass microspheres can cut TPO injection molding production time as much as 20%. This benefit is apparently related to changes in thermal properties that result from displacing resin with hollow glass (reduced mass), and the resulting time savings are concentrated primarily during the cooling period.”

This article comes from plasticstoday edit released

Polyethylene microspheres (also referred to as polyethylene spheres, beads, balls, polymer spheres, polymer microspheres, polymer beads, plastic beads or plastic microspheres) are solid spherical microparticles and are the most common type of solid polymer spheres. Hollow glass microspheres represent a class of additives that offer aesthetic, process control and cost benefits, while providing flexibility in a wide range of potential applications. With advances in microsphere manufacturing processes, polymer spheres and hollow glass microspheres are available in comparable grades, particle sizes and prices.

Which microsphere material is right for your application? There are several major differences to keep in mind when selecting microspheres.

1) Melting Point:

Polyethylene Microspheres – The melting point of polyethylene microspheres varies somewhat depending on the grade and molecular weight of the polymer, but is usually between 110C for low molecular weight grades and 130C for higher molecular weight material. The melting point is typically low and sharp, since polyethylene goes through a fast phase transition. This is a very important feature for applications where the spheres are used as a temporary filler but would need to be “melted away” at a later point to create holes or cavities for a sponge effect.

Hollow glass microspheres – The melting point of hollow glass microspheres is from 500C – 800C, depending on the product. High melting point makes hollow glass microspheres attractive for high temperature applications, where the product needs to withstand severe environmental or processing conditions.

2) Density or Specific Gravity of Particles:

Polyethylene Microspheres – Typical densities of 0.95 g/cc – 1.3 g/cc as well as ability to color-code spheres by density make polyethylene spheres suitable as density marker beads. These are small colored microspheres of known mass density that are used for calibrating density gradients and determining density in gradient columns. Density gradients are often used for separations and purifucations of cells, viruses and subcellular particles. Generally a set of several density marker beads covering a range of densities is used. Custom density particles are available in polyethylene formulations. Brightly colored and fluorescent polymer microspheres are specifically designed as particles for water flow visualization and particle image velocimetry (PIV) experiments. Highly spherical microbeads with tight particle size distribution and density of 1g/cc, matching to properties of fresh water, are used as tracer or seeding particles clearly visible as they follow the flow of the liquid.

Hollow glass microspheres – Solid hollow glass microspheres have a high density of about 2.2g/cc for borosilicate hollow glass microspheres, 2.5g/cc for soda lime hollow glass microspheres, and 4.49g/cc for barium titanate hollow glass microspheres. Hollow glass microspheres have densities as low as 0.14 g/cc.Depending on the application requirements, solvents used, desired buoyancy, difference in density between polyethylene and glass microspheres might become a critical factor when selecting the right material.

3) Chemical Stability:

Polyethylene Microspheres – Most grades of polyethylene have excellent chemical resistance and do not dissolve at room temperature because of their crystallinity. Polyethylene microspheres usually can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylene, or in chlorinated solvents such as trichloroethane or trichlorobenzene. This feature is benefitial if microspheres need to be dissolved at a precise point in the process.
Hollow glass microspheres – Glass has very high chemical resistance and is the right choice for applications where microspheres need to withstand contact with agressive solvents at elevated temperatures.

This article comes from cospheric edit released

Hollow glass microspheres have been used as low-density fillers for various kinds of polymeric compounds since the mid-1960s. For the first 20 years after their introduction, hollow glass microspheres weren’t strong enough to survive the high shear forces and high pressures involved in plastics compounding and injection molding.

Hollow glass microsphere, has the highest compressive strength in the world for such a product. It also has the highest strength-to-density ratio of any glass or other microsphere in the marketplace. Made from soda/lime borosilicate, it can withstand injection molding pressures up to around 30,000 psi.

Relative to earlier glass microspheres, the improved mechanical properties imparted by hollow glass microsphere include better impact strength and elongation, prevention of scratch or stress whitening, tighter tolerances for small parts, and improved surface finish on the end product due to better packing. Greater crush strength means there is much less breakage of the hollow glass microspheres during extrusion or injection molding.

This article comes from ptonline edit released

Polyethylene Microspheres – Pigments, additives, specialty ingredients can be incorporated into polyethylene prior to microsphere manufacturing process. This allows endless possibilities for customization of polyethylene microspheres for specific applications, smaller R&D projects, and unique customer requirements. Colored, fluorescent, phosphorescent, charged, paramagnetic polyethylene microspheres are available.

Hollow glass Microspheres – In general, it is very difficult to incorporate additives into glass. Formulating with a small percent of additives is sometimes possible, but typically additives interfere with the formation of glass and hinder its inherent properties (such as clarity, sphericity, strength, etc). Customization of microspheres with pigments and additives is limited.

Solid glass imparts visual and material benefits that cannot be replicated when spheres are made of other materials such as ceramics or polymerics, aluminum oxides, or silicas and mineral fillers. Solid glass refracts, bends and reflects light. Most ceramics do not transmit light or exhibit mirror-like reflection due to their internal crystalline structures and surface irregularities. Instead of being reflected back, the light is “trapped” in the structure and emitted as diffuse or scattered reflectance, which is not as strong or direct as light transmitted through glass, which produces mirror-like reflectance. Hollow glass microspheres can also possess numerous surface and interior micro irregularities that also diffuse light. Because the thickness of a hollow bead’s wall is inversely proportional to its diameter, however, the larger hollow spheres that might offer some reflective properties have very low crush strengths, which precludes their incorporation into most formulations.

Solid hollow glass microspheres can be made retroreflective by applying a half-shell aluminum coating applied to solid barium titanate hollow glass microspheres. Retroreflective microspheres are hemispherically coated with a thin aluminum shell to produce a bright retroreflective response directed back to the light source and to the observer. The light bounces off the aluminum-coated half of the sphere produces the retro reflective effect that provides the desired high visibility in dark conditions.

This article comes from cospheric edit released

Hollow Glass Microspheres are high-strength, low-density additives made from water resistant and chemically-stable soda-lime-borosilicate glass.

These hollow glass microspheres offer a variety of advantages over conventional irregularly-shaped mineral fillers or glass fiber. Their spherical shape helps reduce resin content in a variety of applications. They also create a ball bearing effect that can result in higher filler loading and improved flow. In this research, amine terminated hollow glass microspheres were prepared by adopting three different routes.

The results were investigated using FT-IR and SEM to establish the formation of amine groups and observe the morphological structure of the modified HGMs. The results obtained were used to select a suitable less toxic and environmental friendly modification method based on the chemicals used.

This article comes from scientific research edit released

Polyurethanes (or urethane polymers) are one of the most versatile materials used today for numerous applications ranging from flexible foam in upholstered furniture to rigid foam as insulation in walls, roofs, and pipes.

To thermoplastics used in medical devices and footwear; to coatings, adhesives, sealants, and elastomers used on floors and automotive interiors.

In this chapter, the use and benefits of hollow glass microspheres in thermoplastic, thermoset, and foam polyurethane system are described.

This article comes from sciencedirect edit released

These bulking agents are hollow glass microspheres that make a low cost, low density filler. Added to epoxy resin and hardener mix, they make a good, heat-resistant, light-weight fairing compound with good compressive strength. Mixture can be blended with a small amount of Silica Thickener to prevent sagging.

Not recommended for glue, alternatively use SilverTip QuikFair for ease-of-use.

This article comes from systemthree edit released