Microfillers

Microfillers are very small filler particles used to fill micro-scale voids and refine the structure of a material. Typically ranging from tens of nanometers to a few micrometers in diameter, microfillers are added to polymers, ceramics, cements, and coatings to alter rheology, improve surface quality, and tune mechanical and thermal properties.

Common inorganic microfillers include silica, silicates, calcium carbonate, glass, and alumina. Organic microfillers can comprise polymer beads or micronized natural fibers. Fillers are often surface treated, for example with silane coupling agents, to promote adhesion with the surrounding matrix and to stabilize dispersion.

In dental composites, microfilled systems use very small filler particles to achieve high polish and esthetic translucency, but typically exhibit lower strength and wear resistance than hybrid systems. In coatings and plastics, microfillers reduce shrinkage, adjust viscosity, and improve abrasion resistance.

Processing and properties: The particle size distribution, shape, and surface chemistry of microfillers govern dispersion, interfacial bonding, and the final performance. Higher filler loading can enhance stiffness and thermal stability but may increase viscosity and hinder processability. Proper surface treatment and compatibility with the matrix are important to balance workability with mechanical outcomes.

Safety and environmental considerations: Handling fine powders requires dust control to minimize inhalation exposure. Waste and production emissions should be managed to limit environmental impact. Regulations may apply depending on the material and application.