Polysulfone chemical resistance

The isopropylidene linkage imparts chemical resistance, the ether linkage imparts temperature resistance, and the sulfone linkage imparts impact strength. The brittleness temperature of polysulfones is — 100°C. Polysulfones are clear, strong, nontoxic, and virtually unbreakable. They do not hydrolyze during autoclaving and are resistant to acids, bases, aqueous solutions, aliphatic hydrocarbons, and alcohols. 

Bisphenol A. One mole of acetone condenses with two moles of phenol to form bisphenol A [80-05-07] which is used mainly in the production of polycarbonate and epoxy resins. Polycarbonates (qv) are high strength plastics used widely in automotive appHcations and appHances, multilayer containers, and housing appHcations. Epoxy resins (qv) are used in fiber-reinforced larninates, for encapsulating electronic components, and in advanced composites for aircraft—aerospace and automotive appHcations. Bisphenol A is also used for the production of corrosion- and chemical-resistant polyester resins, polysulfone resins, polyetherimide resins, and polyarylate resins. 

Polymers are used as inserts for pins and contacts. Important properties of the commonly used insert materials have been compiled (31). Polysulfones are high temperature thermoplastics that have high rigidity, low creep, excellent thermal stabiHty, flame resistance, low loss tangents, and low dielectric constants. The principal weakness of polysulfones is their low chemical resistance. 

Victrex (PES) and Radel (PAS) serve the same end uses and are, like Udel, transparent, slightly yellow polymers exhibiting heat deflection temperatures about 28°C higher than Udel PSO. Their main advantage in electrical and electronic end use is high heat resistance. They also have excellent water and chemical resistance like all polysulfones they are steam sterilizable. Electrical and electronic end uses represent the largest market segment. Applications include connectors, switches, bobbins, and sleeves. 

In the petroleum industry, dewaxing solvents are separated by ultrafiltration from dewaxed oils by chemically resistant membranes made from polysulfone or polyimide. In a related process, pentane is separated from deasphalted heavy oil under conditions intermediate between reverse osmosis and ultrafilttation (ca. 15 bar applied pressure). High-molecular-weight hydrocarbons in the oil form a gel layer on the surface of a polysulfone support membrane. This gel restricts passage of heavier hydrocarbons but not pentane, which is recovered as permeate. To separate other hydrocarbon mixtures that do not contain gel-forming components, polymeric additives would be used as a rejecting barrier substitute. 

Most UF membranes are made from polymeric materials, such as, polysulfone, polypropylene, nylon 6, PTFE, polyvinyl chloride, and acryhc copolymer. Inorganic materials such as ceramics, carbon-based membranes, and zirconia, have been commercialized by several vendors. The important characteristics for membrane materials are porosity, morphology, surface properties, mechanical strength, and chemical resistance. The membrane is tested with dilute solutions of well-characterized macromolecules, such as proteins, polysaccharides, and surfactants of known molecular weight and size, to determine the MWCO. 

Results of some of these short-term tests are shown in Table II. A comparison is given between PPS and five other plastics nylon (Zytel 101), polycarbonate (Lexan 141), polysulfone (Bakelite Polysulfone), polyphenylene oxide (Noryl), and polyetherimide (Ultem 2300). The data presented are based upon retention of tensile strength for all plastics except the Ultem 2300, which is based upon retention of flexural strength. Unsuccessful attempts were made to injection mold ASTM Type IV tensile bars out of the Ultem compound, but flexural strength bars could be made. Experience has shown that chemical resistance tests monitored by flexural strength retention are comparable to those monitored by retention of tensile strength. 

PSF/PET blends show a dispersed morphology. The combination of crystalline PET and amorphous polysulfone provides chemical resistance and warp-free properties. The amount of crystalline polymer is varied to meet requirements in thermal properties and the level of reinforcement is varied to tailor the modulus. The blends have electrical and mechanical properties similar to PET but only a third of its shrinkage and warpage. Also, stress crack resistance to common solvents is improved. Similarly, the service T is upgraded compared to PET. The blends are formed by injection molding and extrusion. 

PET/PSF (polysulfone usually fiber reinforced) warp resistance, dimensional stabihty, stiffness, high temperature performance, chemical resistance. Apphcations include industrial process equipment, electrical connectors, and food processing equipment. 

PPS/PSE blends could offer an interesting compromise in properties with PPS offering chemical resistance and polysulfone offering toughness and excellent thermal stability. PA blends with PSE and PEI could offer advantages in chemical resistance offered by the PA and stiffness at higher temperatures and dimensional stability offered by the engineering polymers. Miscibility of PEI and... 

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