Polyacrylonitrile polysulfone

Regenerated cellulose, cellulose acetate, polyacrylonitrile, polysulfone Nylon, polyester, silk Aliphatic polyesters, regenerated collagen PMMA, UHMWPE Polyester, PTFE Silicones, polyurethanes Silicones... 

Polymer Solvent. Sulfolane is a solvent for a variety of polymers, including polyacrylonitrile (PAN), poly(vinyhdene cyanide), poly(vinyl chloride) (PVC), poly(vinyl fluoride), and polysulfones (124—129). Sulfolane solutions of PAN, poly(vinyhdene cyanide), and PVC have been patented for fiber-spinning processes, in which the relatively low solution viscosity, good thermal stabiUty, and comparatively low solvent toxicity of sulfolane are advantageous. Powdered perfluorocarbon copolymers bearing sulfo or carboxy groups have been prepared by precipitation from sulfolane solution with toluene at temperatures below 300°C. Particle sizes of 0.5—100 p.m result. 

Polydithiazoles Polyoxadiazoles Polyamidines Pyrolyzed polyacrylonitrile Polyvinyl isocyanate ladder polymer Polyamide-imide Polysulfone Decompose at 525°C (977°F) soluble in concentrated sulfuric acid. Decompose at 450-500°C (842-932°F) can be made into fiber or film. Stable to oxidation up to 500°C (932°F) can make flexible elastomer. Stable above 900°C (1625°F) fiber resists abrasion with low tenacity. Soluble polymer that decomposes at 385°C (725°F) prepolymer melts above 405° C (76l.°F). Service temperatures up to 288° C (550°F) amenable to fabrication. Thermoplastic use temperature —102°C (—152°F) to greater than 150° C (302°F) acid and base resistant. 

Membranes UF membranes consist primarily of polymeric structures (polyethersulfone, regenerated cellulose, polysulfone, polyamide, polyacrylonitrile, or various fluoropolymers) formed by immersion casting on a web or as a composite on a MF membrane. Hydrophobic polymers are surface-modified to render them hydrophilic and thereby reduce fouling, reduce product losses, and increase flux [Cabasso in Vltrafiltration Membranes and Applications, Cooper (ed.). Plenum Press, New York, 1980]. Some inorganic UF membranes (alumina, glass, zirconia) are available but only find use in corrosive applications due to their high cost. 

With either type of dialysis, studies suggest that recovery of renal function is decreased in ARF patients who undergo dialysis compared with those not requiring dialysis. Decreased recovery of renal function may be due to hemodialysis-induced hypotension causing additional ischemic injury to the kidney. Also, exposure of a patient s blood to bioincompatible dialysis membranes (cuprophane or cellulose acetate) results in complement and leukocyte activation which can lead to neutrophil infiltration into the kidney and release of vasoconstrictive substances that can prolong renal dysfunction.26 Synthetic membranes composed of substances such as polysulfone, polyacrylonitrile, and polymethylmethacrylate are considered to be more biocompatible and would be less likely to activate complement. Synthetic membranes are generally more expensive than cellulose-based membranes. Several recent meta-analyses found no difference in mortality between biocompatible and bioincompatible membranes. Whether biocompatible membranes lead to better patient outcomes continues to be debated. 

Many membrane materials have been developed and are used for hemodialyzers. Today, these include regenerated cellulose, cellulose acetate, polyacrylonitrile, poly(methylmethacrylate), vinyl alcohol-ethylene copolymer, polysulfone, polyamide, and others. 

A wide range of polymers has been used as membrane materials including polyacrylonitrile [216, 221-224], polysulfone [219, 225], nylon [218] and dextran... 

Most of today s ultrafiltration membranes are made by variations of the Loeb-Sourirajan process. A limited number of materials are used, primarily polyacrylonitrile, poly(vinyl chloride)-polyacrylonitrile copolymers, polysulfone, poly(ether sulfone), poly(vinylidene fluoride), some aromatic polyamides, and cellulose acetate. In general, the more hydrophilic membranes are more fouling-resistant than the completely hydrophobic materials. For this reason water-soluble... 

The first major application of microfiltration membranes was for biological testing of water. This remains an important laboratory application in microbiology and biotechnology. For these applications the early cellulose acetate/cellulose nitrate phase separation membranes made by vapor-phase precipitation with water are still widely used. In the early 1960s and 1970s, a number of other membrane materials with improved mechanical properties and chemical stability were developed. These include polyacrylonitrile-poly(vinyl chloride) copolymers, poly(vinylidene fluoride), polysulfone, cellulose triacetate, and various nylons. Most cartridge filters use these membranes. More recently poly(tetrafluo-roethylene) membranes have come into use. 

In hemodialysis, blood from the patient flows on one side of a membrane and a specially prepared dialysis solution is fed to the other side. Waste material in the blood such as urea, excess acids, and electrolytes diffuse into the dialysate the blood is then returned to the patient, as shown in Fig. 48. A patient typically undergoes dialysis three times per week in sessions lasting several hours each. Modern dialysis systems combine sophisticated monitoring and control functions to ensure safe operation. Regenerated cellulose was the first material used in hemodialysis membranes because of its biocompatibility and low cost it remains the most popular choice. Subsequently, high-permeability dialysis membranes derived from cellulose esters, modified polysulfone, or polyacrylonitrile copolymers have also gained wide acceptance because of the shorter sessions they make possible. 

ID, internal diameter ED, external diameter CA, cellulose acetate CTA, cellulose triacetate PA, polyamide PAN, polyacrylonitrile PC, polycarbonate PE, polyethylene PES, polyethersulfone PP, polypropylene PS, polysulfone PVDF, polyvinylidene fluoride PVP, polyvinyl pyrrolidone RC, regenerated cellulose. 

Typical UF membrane materials are polysulfone (PS), poly ether sulfone (PES), polyetheretherketone (PEEK), cellulose acetate (CA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyimide (PI), and polyetherimide (PEI) ... 

Sztajer and Bryjak [48] have taken an entirely different approach to the purification of the lipase from Pseudomonas fluorescens by investigating the use of ultrafiltration capillary membranes. A two-step procedure involving continuous fractionation of the protein on polyacrylonitrile membrane followed by concentration on polysulfone membranes is suggested for continuous lipase recovery. They observe that the permeate fluxes through both membranes are similar, thereby suggesting that changing the production scales should not be difficult. 

---