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
