Filler (materials)

Filler materials are particles added to binders (resin, thermoplastics, cement) to make a composite material. Filler materials improve specific properties or make the product cheaper.^[1]

Coarse filler materials such as construction aggregate and rebar are used in the building industry to make plaster, mortar and concrete.

Powdered fillers are mixed in with elastomers and plastics.^[2] Worldwide, more than 53 million tons of fillers (with a net worth of ca. US$18 billion) are used every year in the production of paper, plastics, rubber, paints, coatings, adhesives, and sealants. Fillers are produced by more than 700 companies, rank among the world's major raw materials and are contained in a variety of goods for daily consumer needs. The top filler materials used are ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), kaolin, talc, and carbon black.^[3]

Filler materials can affect the tensile strength, toughness, heat resistance, color, clarity, etc. This can be utilised to modify or enhance the material properties, or as a way to improve and control the processing charasteristics.^[4] Another reason to use fillers is to reduce costs by replacing part of the expensive core material with a cheaper filler.

Most of the filler materials used in plastics are mineral or glass based filler materials.^[5] Particulates and fibers are the main subgroups of filler materials. Particulates are small particles of filler that are mixed in the matrix where size and aspect ratio are important. Fibers are small circular strands that can be very long and have very high aspect ratios.^[6]