China UDEL PSU Manufacturer, Supplier, Factory

Udel® Polysulfone (PSU)

UDEL PSU resins offer a superior combination of highperformance properties that include:

• Excellent thermal stability

• High toughness and strength

• Good environmental stress cracking resistance

• High heat deflection temperature, 174°C (345°F)

• Combustion resistance

• Transparency

• Approved for food contact and potable water

• Low creep

This manual has been compiled to provide design engineers with the necessary information to effectively use Udel® PSU. It contains the mechanical, thermal, and chemical properties of these materials and recommendations for processing and part design. Chemical and Property Relationships Udel® PSU is a rigid, strong, high-temperature amorphous thermoplastic that can be molded, extruded, or thermoformed into a wide variety of shapes. Udel® PSU has the following repeating structure or basic unit:

This structural unit is composed of phenylene units linked by three different chemical groups – isopropylidene, ether, and sulfone – each contributing specific properties to the polymer. The complex repeating structure imparts inherent properties to the polymer that conventionally are gained only by the use of stabilizers or other modifiers. The most distinctive feature of the backbone chain is the diphenylene sulfone group:

diphenylene sulfone

The influence of diphenylene sulfone on the properties of resins has been the subject of intense investigation since the early 1960’s. The contributions of this group become evident upon examination of its electronic characteristics. The sulfur atom (in each group) is in its highest state of oxidation. Furthermore, the sulfone group tends to draw electrons from the adjacent benzene rings, making them electron-deficient. Thermal stability is also provided by the highly resonant structure of the diphenylene sulfone group. This high degree of resonance imparts high strength to the chemical bonds. Substances stable to oxidation strongly resist the tendency to lose their electrons to an oxidizer. It then follows that the entire diphenylene sulfone group is inherently resistant to oxidation. Therefore, large amounts of incident energy in the form of heat or ionizing radiation can be dissipated without chain scission or crosslinking taking place. Non-aromaticbackbone polymers do not similarly resonate, cannot absorb energy by this mechanism, and are therefore less stable. The diphenylene sulfone group thus confers on the entire polymer molecule, as inherent characteristics, thermal stability, oxidation resistance, and rigidity, even at elevated temperatures. To take full advantage of the potentially available contributions of the diphenylene sulfone structure in a thermoplastic resin, these units must be linked with other groups, which are thermally and hydrolytically stable, and which will contribute desirable processing and end use properties. Some flexibility in the backbone of the polymer is desired to impart toughness. This is provided by the ether linkage and moderately augmented by the isopropylidene link. These ether linkages also add to the thermal stability. Similarly, both the ether and isopropylidene linkages impart some chain flexibility, making the material more easily processable at practical temperatures. The chemical structure of polysulfone is thus directly responsible for an excellent combination of properties that are inherent in the resins – even without the addition of modifiers. Polysulfone is rigid, strong, and tough. It is transparent in its natural form and maintains its physical and electrical properties over a broad temperature range. Its melt stability permits fabrication by conventional thermoplastic processing and fabrication techniques. It is resistant to oxidation and thermally stable, and therefore, can tolerate high use temperatures for long periods of time.