Polysulfone polymers, properties

Electrical properties -of plastics [PLASTIC TESTING] (Vol 19) -of polysulfone [POLYMERS CONTAINING SULFUR - POLYSULFONES] (Vol 19)... 

Polyaryl sulfone consists mainly of phenyl and biphenyl groups linked by thermally stable ether and sulfone groups. It is distinguished from polysulfone polymers by the absence of aUphatic groups, which are subject to oxidative attack. This aromatic structure gives it excellent resistance to oxidative degradation and accounts for its retention of mechanical properties at high temperatures. 

Electrochemical biosensor performance such as sensitivity, protein stability, selectivity or reproducibility have been improved due to the use of different carbonaceous materials and combination of them. To improve the sensitivity of a electrochemical biosensor is necessaiy to increase the enzyme amount in a proper immobilization manner. CNTs are good candidates and in this regard, some authors combine carbon nanomaterials with conducting polymers, which gives rise the biosensor special properties due to the synergic effect of the individual components. The electrochemical determination of lactate by the use of lactate oxidase (LOx) based SPE platform takes advantages of the combination of MW-CNT and conductive polysulfone polymer, and such an electrochemical biosensor was successfully applied for the quantification of lactate in wine and beer. In some cases, the inconvenient is the low stability associated with the deleterious interaction of the enzyme LOx with the composite CNT/polymer substrate. 

New phosphorus containing polysulfones could be obtained by using different phosphorus containing diols in the classical synthesis of PSF (Scheme 6.4). Diols can contain phosphorus in main chain position or incorporate in a phenanthrene-type ring as side chain. These different phosphorus-containing diols form aromatic polyethers by polycondensation with dihalogen-substituted aromatic sulfones [48]. The chain structure of the polymer (aromatic or aliphatic) and the position of phosphorus in the chain influence the polymer properties (electroluminescence [49,50], flame retardancy [51], liquid crystal properties [52]). 

No books solely focused on polysulfone polymers or blends of polysulfones are available. A good general source of information on many of the general features of polysulfones is the Society of Plastics Engineers (SPE) encyclopedia. There, information about many of the chemical and physical properties can be found. 

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. 

The aromatic sulfone polymers are a group of high performance plastics, many of which have relatively closely related stmctures and similar properties (see Polymers containing sulfur, polysulfones). Chemically, all are polyethersulfones, ie, they have both aryl ether (ArOAr) and aryl sulfone (ArS02Ar) linkages in the polymer backbone. The simplest polyethersulfone (5) consists of aromatic rings linked alternately by ether and sulfone groups. 

Electrical Properties. Polysulfones offer excellent electrical insulative capabiUties and other electrical properties as can be seen from the data in Table 7. The resins exhibit low dielectric constants and dissipation factors even in the GH2 (microwave) frequency range. This performance is retained over a wide temperature range and has permitted appHcations such as printed wiring board substrates, electronic connectors, lighting sockets, business machine components, and automotive fuse housings, to name a few. The desirable electrical properties along with the inherent flame retardancy of polysulfones make these polymers prime candidates in many high temperature electrical and electronic appHcations. 

An excellent review of composite RO and nanofiltration (NE) membranes is available (8). These thin-fHm, composite membranes consist of a thin polymer barrier layer formed on one or more porous support layers, which is almost always a different polymer from the surface layer. The surface layer determines the flux and separation characteristics of the membrane. The porous backing serves only as a support for the barrier layer and so has almost no effect on membrane transport properties. The barrier layer is extremely thin, thus allowing high water fluxes. The most important thin-fHm composite membranes are made by interfacial polymerization, a process in which a highly porous membrane, usually polysulfone, is coated with an aqueous solution of a polymer or monomer and then reacts with a cross-linking agent in a water-kniniscible solvent. 

Many engineering thermoplastics (e.g., polysulfone, polycarbonate, etc.) have limited utility in applications that require exposure to chemical environments. Environmental stress cracking [13] occurs when a stressed polymer is exposed to solvents. Poly(aryl ether phenylquin-oxalines) [27] and poly(aryl ether benzoxazoles) [60] show poor resistance to environmental stress cracking in the presence of acetone, chloroform, etc. This is expected because these structures are amorphous, and there is no crystallinity or liquid crystalline type structure to give solvent resistance. Thus, these materials may have limited utility in processes or applications that require multiple solvent coatings or exposures, whereas acetylene terminated polyaryl ethers [13] exhibit excellent processability, high adhesive properties, and good resistance to hydraulic fluid. 

ABS has a specific gravity of 1.03 to 1.06 and a tensile strength in the range of 6 to 7.5 X 10 psi. These polymers are tough plastics with outstanding mechanical properties. A wide variety of ABS modifications are available with heat resistance comparable to or better than polysulfones and polycarbonates (noted later in this section). Another outstanding property of ABS is its ability to be alloyed with other thermoplastics for improved properties. For example, ABS is alloyed with rigid PVC for a product with better flame resistance. 

Polysulfones (PSU) and polyphenylsulfones (PPSU) can be modified by alloying with ABS, PBT, PC or proprietary polymers. The main sought-after characteristics are lower cost and easier processing, combined with a good balance of mechanical, thermal and chemical properties. 

A number of plastics are condensation polymers and include polyesters and nylons that are not as highly oriented as the same materials but in fiber form. Other plastics have been developed that have outstanding heat stability, strength, and other properties that allow their wide use. These plastics include polycarbonates, polyimides, polybenzimidazoles, polysulfides, polyethers, polysulfones, and polyketones. 

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