Polysulfones Compressibility

Over 30 commercial formulations have been surveyed in depth. Compressive strength measurements permit the exclusion of materials obviously prone to fail under pressure. FTIR (MX-1, Nicolet Instrument Corp.) analysis has identified formulations with volatile diluents capable of chemically modifying the composite membrane. Through the use of FTIR it was possible with an otherwise successful formulation to identify the presence of butyl glycidyl ether (BGE) as a diluent. Subsequently experimentation showed that vapor of BGE is capable of plasticizing porous polysulfone with a drop in both flux and rejection of the membrane. Collaboration with the supplier resulted in substitution of a nonvolatile glycidyl ether diluent to avoid the problem. 

The Li-Loos intimate contact model was verified for compression molded unidirectional graphite-polysulfone and graphite-PEEK (APC-2) laminae and graphite-PEEK (APC-2) cross-ply laminates. The degrees of intimate contact of the unidirectional and cross-ply specimens were measured by optical microscopy and scanning acoustic microscopy, respectively. The predicted degrees of intimate contact agreed well with the measured values for both the unidirectional and cross-ply specimens processed at different temperature and pressures. 

Figure 3. High-temperature mechanical behavior of bis-A-polysulfone/bis-A-polycarbonate (16,000/17,000) block copolymer. Compression molded at 260°C.

The initial microporous support films used in the work were made from cellulose acetate by a modification of the Loeb-Sourirajan procedure. Later work showed that several types of the membrane filters manufactured by Millipore Corporation and Gelman Sciences, Inc., performed as well and allowed higher flux. A continued search for a more compression-resistant support film led to the development of polycarbonate, polyphenylene oxide and polysulfone microporous films in 1966 to 1967 (8). Of these, microporous polysulfone film proved to have the best properties. The polysulfone support was made by casting a liquid layer of a 12.5 to 15 percent solution of Union Carbide Udel P35OO polysulfone in dimethylformamide onto a glass plate at 4 to 7 mils (100-175 pm) thickness, then coagulating the film in water. 

Determination of Unassociated and Clustered Water. Compression molded samples of polysulfone were Immersed in water at 100°C and below until they came to equilibrium. Above 100 C an autoclave was used. As with polycarbonate a mild temperature dependence in equilibrium absorption was noted. The amount of unassociated water at saturation went from 0.8% at 23°C to 1.2% at 132°C. No clustered water was found in samples exposed below... 

In the fall of 1966, researchers at North Star Research Institute began a search for compression-resistant microporous substrates.19 This effort resulted in the development of microporous sheets of polycarbonate (Lexan) and poly-sulfone (Udel).20 Figure 5.4 shows a graph comparing the flux levels and flux stability for three membranes made at that time (a) float-cast cellulose acetate on microporous polysulfone, (b) float-cast cellulose acetate on a mixed cellulose ester microfilter support and (c) a standard asymmetric cellulose acetate membrane. The improvement in membrane fluxes was readily apparent, when switching from cellulosic substrates to the microporous polysulfone substrate. 

Figure 10.6 The tensile strength of polystyrene and the compressive strength of polysulfone vs. Mn, for narrow MWD samples (from Mills, N. J., Rheolog. Aaa, 13, 185, 1974),...

Polysulfones Thermoplasties, often aromatic with ether linkages has good heat, fire, and ereep resistance, dieleetrie properties, transpareney, but poor weatherability, proeessability, and stress eraeking resistance. Processed by injection, compression, and blow-molding and extrusion. Used in applianees, eleetronie deviees, auto parts, and electrie insulators. Also ealled PSO. 

Compressed CO2 and N2O plasticize polysulfone. N2O is more polar than CO2 and it is slightly more effective in plasticization of polysulfone. ... 

Problems associated with the use of prepreg for composite fabrication included a high bulk factor and difficulties in obtaining an optimum resin pre-cure to ensure correct consolidation. One approach was to use pressure assisted resin injection, where a fiber preform contained in a mold was evacuated and a fairly mobile resin pumped in under pressure [64]. To help maintain the accurate alignment of the fiber in the perform, it was held in place by a resin binder made of about 4% polysulfone applied as a solution in methylene chloride, drying to remove solvent and then followed by a short treatment at 320° C to fuse the polysulfone onto the fiber. Next, a laminate of primed sheets was prepared, which was about 2.5 times the bulk volume of the finished composite (i.e., when compressed at 0.65 f/). Two techniques were used to consolidate a preform. 

McGrath, Robeson, and Matzner investigated block copolymers and homopolymer-copolymer blends of bisphenol-A polysulfone and nylon-6 (7). They found improved ESCR as the content of the crystalline nylon-6 block increased. Similarly, Viswanathan, al. prepared random block copolymers of bisphenol-A pFTysulfone and the partially crystalline hydroquinone polysulfone (8). ESCR improved markedly as the hydroquinone content increased. However, while the copolymers "as made" are semicrystalline, the compression molded specimens used for ESCR studies are amorphous. Hence, recrystallization from the melt was quite slow. The improvement of ESCR is attributed to solvent-induced crystallization of the surface layers, which was presumed to restrict diffusion of the liquid into the bulk. 

A variety of polymeric materials have been studied or used for preparing dentures, including epoxy resins, cellulose nitrate, rubber or vulcanite, phenol-formaldehyde, vinyl acrylics, polystyrene, polycarbonates, and polysulfones, but acrylics have become the materials of choice. It happens that compression-molded, cross-linked acrylic dentures are as dimensionally stable and useful as the dentures made with special resins (4). 

The polymers included in this study are bisphenol-A polycarbonate (Bis-A PC), polyesteicarbonates (PEC), whose structures are defined in Figure 1, phenolphthalein bisphenol-A copolycarbonate, and polysulfone. All samples were compression molded and physically aged as described elsewhere, with the exception of those for the Fourier transform infrared (FTIR) measurements and solid state variable temperature nuclear magnetic resonance (VTNMR)... 

Polyphenylene oxide was used by Cabasso to prepare the double-layer composite membranes. These membranes consist of two different polymers deposited on a highly porous glassy polymer like polysulfone. The top separating layer was PPO and second intermediate gutter layer was poly (dimethyl siloxane), a highly permeable polymer. The double layer was about 1 micron thick with the top layer thickness being 0.2 microns or less. This membrane showed a separation factor of 4.1 for O2/N2 using compressed air as the feed. 

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