Component made of foamed particles for sound absorption involves irregular shaped particles to produce high pore volume

摘要

Components are made by sintering foamed particles, which are of irregular shape and have a greater surface area than spherical particles of the same density without any internal hollow spaces. The irregular packing produces a pore volume of 4 to 70%. The particles are produced by breaking up thermoplastic foamed particles or film or by an extrusion or autoclave process. The extrusion process uses a die (7) with non-circular holes. As the material (2) emerges from the hole exit (4), the foaming agent causes it to expand and it is then cut off by a rotating cutter (3) to produce an irregular shaped particle (5). The particles are sintered in a mould under slight pressure to form the component, using steam, high frequency radiation, infra-red radiation or hot air.