Poly sulfones mechanical

Figure 1. High-temperature mechanical behavior of interfacially prepared bis-A-poly sulfone/bis-A-poly carbonate (10,000/10,000) block copolymer...

PA/PSF with poly(sulfone-g-lactam) processability and mechanical properties McGrath and Matzner, 1972... 

Immiscible PES blends with improved properties are composed from poly-(biphenyl ether sulfone) and poly(l,4-phenylene ether sulfone). Ternary resin blends comprising a poly(biphenyl ether sulfone), a poly(ether sulf-one) and a poly(sulfone), exhibit very attractive thermal and environmental resistance characteristics together with excellent mechanical properties. 

Homopolymers derived from MDI and azelaic acid are semicrystalline engineering plastics with a Tg of 135°C and a Tm of 290°C (88). Copoljrmers of MDI with azelaic acid, containing 20-30 mol% of adipic acid show a eutectic Tm of approximately 240°C. These amorphous or slightly crystalline copolymers have mechanical properties comparable to transparent nylons or polycarbonates. Although injection molded samples are transparent, they will crystallize and turn opaque. Copolyamides derived from MDI and aromatic dicarboxylic acids are more difficult to prepare. Because of the very high Tm (420°C) of the isophthalic acid/MDI block it was necessary to prevent the formation of any appreciable ciystalline blocks, which was accomplished by prereacting a portion of the isophthalic acid (15-20 mol%) with 2,4-TDI. In this manner crystallization of the isophthalic acid/MDI blocks was surpressed (89). Thus, copolyamides containing IPA/azelaic acid (50 50) are obtained with thermal and mechanical properties similar to poly-sulfone. 

Poly(arylene ether ketone) and poly(arylene ether sulfone) were also tried to be incorporated into the hybrids with silica gel by means of the sol-gel procedure [19, 20], For example, triethoxysilyl-terminated organic polymer was subjected to co-hydrolysis with tetraethoxysilane. A systematic change in mechanical and physical properties of the hybrid glass has been found with the content of organic polymer and the annealing temperatures. 

The most radiation-stable poly(olefin sulfone) is polyethylene sulfone) and the most radiation-sensitive is poly(cyclohexene sulfone). In the case of poly(3-methyl-l-butene sulfone) there is very much isomerization of the olefin formed by radiolysis and only 58.5% of the olefin formed is 3-methyl-l-butene. The main isomerization product is 2-methyl-2-butene (37.3% of the olefin). Similar isomerization, though to a smaller extent, occurs in poly(l-butene sulfone) where about 10% of 2-butene is formed. The formation of the olefin isomer may occur partly by radiation-induced isomerization of the initial olefin, but studies with added scavengers73 do not support this as the major source of the isomers. The presence of a cation scavenger, triethylamine, eliminates the formation of the isomer of the parent olefin in both cases of poly(l-butene sulfone) and poly(3-methyl-1-butene sulfone)73 indicating that the isomerization of the olefin occurred mainly by a cationic mechanism, as suggested previously72. 

However, Pacansky and his coworkers77 studied the degradation of poly(2-methyl-l-pentene sulfone) by electron beams and from infrared studies of the products suggest another mechanism. They claim that S02 was exclusively produced at low doses with no concomitant formation of the olefin. The residual polymer was considered to be essentially pure poly(2-methyl-l-pentene) and this polyolefin underwent depolymerization after further irradiation. However, the high yield of S02 requires the assumption of a chain reaction and it is difficult to think of a chain reaction which will form S02 and no olefin. 

Scheme 6.12 Proposed mechanism for the synthesis of poly(arylene ether sulfone) via the potassium carbonate process.8...

Other coupling reactions were also employed to prepare poly(arylene etherjs. Polymerization of bis(aryloxy) monomers was demonstrated to occur in the presence of an Fe(III) chloride catalyst via a cation radical mechanism (Scholl reaction).134 This reaction also involves carbon-carbon bond formation and has been used to prepare soluble poly(ether sulfone)s, poly(ether ketone)s, and aromatic polyethers. 

Ion exchange resins based on poly(styrene-divinylbenzene) backbones display mixed mode retention mechanisms. The ion exchange functionality (sulfonic acid or carboxylic acid for cation exchangers and quartemary or primary, secondary, or tertiary amines for anion exchangers) contributes to the ionic mechanism and the backbone polymer to hydrophobic retention. This is exemplified... 

Interesting observations are made, if a polymeric adsorbate is capable of more than one mechanism of adsorption. If poly(styrene sulfonate) (PSS) is adsorbed on carbon black which contains multivalent cations on its surface, the adsorption depends strongly on the nature of the cations and on pH, with a maximum near pH 7. At very alkaline pH s, the OH ions compete with the sulfates for the cations and the PSS adsorption drops to the low values of hydrophobic bonding between the carbon itself and the PSS backbone. The latter low values are also obtained, if PSS is adsorbed on the same carbon after purification, i.e. when oxygen and/or the cations were removed. This adsorption of PSS is now pH independent (29). 

Of all the hydrocarbon-based PEMs, this group most likely has the largest variety of different systems. This is probably due to the wealth of prior knowledge of the nonsulfonated analogues that have been developed over the last several decades as well as the general expectation of higher thermal stability, better mechanical properties, and increased oxidative stability over polystyrene-based systems. Within the context of this section, polyarylenes are systems in which an aryl or heteroaryl ring is part of the main chain of the polymer. This section will, therefore, include polymers such as sulfonated poly (ether ether ketone) and sulfonated poly(imides) but will not include systems such as sulfonated polystyrene, which will be covered in Section 3.3.I.3. 

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