What is PEEK Powder (Polyetheretherketone) PEEK is a high-performance thermoplastic polymer powder that is known for its exceptional mechanical, thermal, and chemical properties. It is used in a wide array of industries due to its high temperature and chemical resistance, as well as its mechanical strength and electrical insulation properties. When producing PEEK powder, controlling particle size is an extremely important factor. PEEK can be extremely difficult to screen due to its tendency to agglomerate due to static, poor flow, and extremely spherical properties. If these are not handled properly, sieving and classifying the product can be very difficult.