Hollow glass microspheres are a free-flowing, oleophilic product that is low in density (0.19g/cm3 ) and small in particle size (75µm, avg). This product is especially suited for use in adhesive applications.

When hollow glass microsphere is added to a “workhorse” epoxy resin system (bisphenol-A, cured with a modified aliphatic amine) at volume levels of 9 and 18%, resin density is reduced substantially, while lap-shear adhesive strength is retained, and in some cases, improved.

Additionally when used to augment the same resin system containing conventional solid fillers (calcium carbonate with fumed silica), hollow glass microspheres impart similar benefits. The data collected in the study illustrate the benefits gained from the use of hollow glass microspheres in the epoxy system.

Benefits include:

• Formulation density reduction, leading to cost savings.

• Maintenance of adhesive performance, potential improvement in bond strength at ambient temperatures and after exposure to elevated temperature stress.

• Viscosity optimization of the formulation, aiding in sag prevention and development of adequate “glue-line”.