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.

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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.

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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.

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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.

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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.

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This is a white-colored, fused borosilicate glass in a hollow microsphere or bubble form. This product has a bulk density of 0.26 g/cc and a maximum working pressure of 4,000 psi.

Hollow glass microphere is most commonly used to increase thermal and acoustic insulation in autobody sealant and coating applications.

Sphericel hollow glass microspheres are used as lightweight additives in plastic parts as well as to enhance performance and reduce viscosity in paints and coatings.

Hollow glass micropheres are chemically inert, non-porous, and have very low oil absorption.

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Rapid development in the field of deep-sea exploration in the middle of the 20th century was one of the main reasons for development of hollow glass microsphere (HGM) technology. Development engineers of deep submergence vehicles required new structural materials with densities less than those of water but of high compression strength and water resistance. Syntactic composites based on HGMs were able to meet these requirements. Structural elements made using these materials are capable of withstanding water pressure down to 6000 m.

Hollow glass microspheres form a white coloured powder consisting of tiny bubbles with diameters ranging between 20-150 μm with walls thicknesses less than 1 μm. The glass composition and the near perfect spherical shape of the microspheres provide high compressive strength. The main distinction between high and low grade HGMs is their shape and structure. Lower quality HGMs fail under less load, less predictably, compared to high grade HGMs. Other key properties include low water absorption, low heat conductivity, high chemical resistance and radio transparency.

Good adhesion of HGMs towards polymer binders makes them ideal for composites giving a unique combination of properties. All the above-mentioned factors define a wide variety of applications for HGMs.

The technology for HGM manufacture is a combination of complex hydrodynamic and chemical processes that take place in the course of forming of hollow bubbles blown from microparticles of glass melt. An exact dosage of gas into the melted powder blows microspheres with the required diameter and wall thickness. With such a complex technological process it is impossible to make microspheres with a strictly identical predetermined diameter. Therefore calibration of microspheres is performed according to their dimensions. The strength of the microspheres is established by testing the hydrostatic pressure at which not more than 10% of the HGMs fail. It is natural that microspheres with a greater density – and thus with thicker walls – are stronger.

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Hollow Glass Microsphere is a kind of hollow spherical powdered ultralight inorganic nonmetallic materials.

The Properties of Hollow Glass Microsphere

Pure white color, Hollow Glass Microsphere can be widely used in products which have high requirements for looks and colors.

Low density, reducing the products’basic weight obviously after filling. (the density of HGS is one out of a dozen of traditional filler particles’ density). Relatively large volume, which can substitute and save more resins, reducing cost.

High dispersion and good fluidity, dimensional stability, reduced warpage and shrinkage when used as additives.

Heat insulation, sound insulation, mostly used as heat insulation paints and coatings, automotive sealants.

In addition, corrosion resistant, fire resistant, non-conducting.

Application Area

a. lightweight cement, low-density oil well cementing slurry & low-density drilling fluids additive.
b. low-density FRP(fiberglass-reinforced plastic), SMC, BMC composites.
c. low-density adhesives & sealants
d. heat insulation paints and coatings
e. Construction (reducing warpage/shrinkage)
f. Insulation and Buoyancy
g. artificial marble

Our hollow glass microspheres can be used in paint and coatings, construction sealant, rubber, plastic, FRP, artificial stone, putty and other products as filler and weight-reducing agent. The glass bubbles can also be used to produce high-strength, low-density cement slurry and low-density drilling fluid in oil and gas extraction industry. more and more industries now trying to testing the hollow glass spheres as additives to improve their products’ properties.

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Since the dawn of mankind, there has been a drive to develop lighter materials to enable transport and ease of use. After the industrial revolution and the subsequent development of plastics, there have been ongoing material substitutions from metal, glass, wood, and stone to plastics and composites of these materials to reduce weight.

A logical next step in hollow glass microspheres evolution was to reduce the weight of plastics. Various, naturally low in density, fillers were first tried with limited density modification capability. In addition, injection or creation of gas in the polymer during the article forming process was also developed and utilized in nonstructural applications such as packaging.

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What are Glass Bubbles?

Additives, especially inorganic solid particulates, have greatly contributed to the growth of the polymer industry. They render polymers with improved mechanical, physical, electrical, thermal and dimensional properties, depending on their geometry and chemistry. Glass bubbles are finely dispersed, free-flowing powders consisting of thin-walled (0.5-1.5µm) spherical glass particles with an average diameter of 15-65µm.

Glass bubbles were developed in the 1960s as an outgrowth from the manufacture of solid glass beads. They are commercially manufactured by melting a unique glass formula that contains a latent blowing agent causing the molten glass particles to expand into a hollow bubble. The resultant glass bubbles are chemically stable, water resistant and compatible with many materials used for indirect food contact applications. The material technology has evolved in recent years to produce bubbles with a high strength to density ratio which enables their use in demanding polymer processing operations.

Density Reduction in Polymer Composites

Glass bubbles can provide new and unique material and design solutions for innovative users. They render polymers with lower density which is directly related to thermal conductivity and insulation properties. Polyurethane foam for appliance insulation is usually made with a chemical blowing agent and can achieve a very low density (0.20 – 0.40 g/cc). Typical polyurethane composite density with glass bubbles is in the 0.76 – 0.95 g/cc range so they are not competitive with urethane for achieving the highest insulation properties. But the unique property of the glass bubble foam is that it is rigid and structural and can be applied to the walls and housings themselves for additional insulation value.

Weight or mass reduction can be helpful in other ways such as helping to reduce shipping costs and ease installation issues. Glass bubbles can provide weight reduction for thermoplastics, thermosets and elastomeric polymer substrates.

The addition of glass bubbles to a polymer will result in physical property changes (density being the obvious one). Typically glass bubble addition will cause the composite to become stiffer than the original unfilled base resin. This can be useful for making stronger yet lighter housings and parts but impact strength is usually inversely related to stiffness. Impact usually becomes the property of focus for material specifiers trying to balance the benefits of mass reduction with other physical properties.

The choice of a specific bubble for a given application is important to maximize density reduction and to minimize cost-in-use. Not all glass bubbles can survive all polymer processing methods. As shown in Figure 2, the relationship of strength to density is important in selecting the lowest density glass bubble that will survive the process. With thermoset materials like polyurethanes and epoxies the predictive step in the process is the type of mixing system used. For high shear thermoset mixers such as Cowles mixers, a 3000 PSI bubble or higher strength material is generally required. For thermoplastics and rubber where there is only an extrusion process involved (e.g. sheet extrusion for thermoforming), then typically at least a 5000 PSI bubble is required. Injection molded thermoplastics require the highest compressive strength bubble – generally 16,000 PSI or greater. Finding the lowest density bubble that survives the process will insure the lowest cost in use since the least amount by weight will be required to achieve the targeted composite density.

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