Fillers are substances or materials which are added into the composition of polymer composites with the purpose of modification of their operating ability, facilitation of processing, as well as cost reduction. They are principally inorganic or organic solids of natural (mineral or plant) or artificial origin.

      Reinforcing fillers take up the principal load in a polymer composite and determine its physical-mechanical indices. Taking into consideration the operation conditions of a polymer composite material it is possible, by selection of the primary components (the type of the reinforcing material and the type of the binding substance), to get a product with specified parameters.

     The most common types of reinforcing fillers are glass-fibre yarns, rovings (tows), tapes and fabrics. Products reinforced with glass-fibre fillers are characterised by a high strength, low thermal conductivity and density, radio transparency, chemical resistance, weather resistance and possess good insulating and dielectric properties.