Polysulfone (PSU) - A family of sulfur-containing thermoplastics, closely related to polyethersulfone (PES). The structure of the polysulfones is aromatic groups, generally with more than one benzene ring, joined by a sulfone group. Generally, polysulfone is a high cost, rigid, amorphous material with low moisture absorption. Reinforcement improves toughness and further enhances dimensional stability, but turns materials opaque. In addition, polysulfones are characterized by high strength, very high surface-temperature limits, low creep, good electrical characteristics, transparency, self-extinguishing ability, and resistance to greases, many solvents, and chemicals. Polysufones may be processed by extrusion, injection molding, and blow molding.