High-temperature sulfone polymers structure

Figure 1.15 Structure of high-temperature sulfone polymer.

In 2004 Solvay Advanced Polymers introduced these HTS under the Supradel trademark. In 2007 the trademark was changed to EpiSpire. The structure appears in Eig. 1.15. HTS is a high-temperature amorphous polymer. The more rigid biphenyldisul-fone unit results in polymer with a of265°C, which is noticeably higher than TgS other sulfone polymers [30,31]. The structure of HTS appears in Fig. 1.15. 

Solid state NMR has been used to study polymers of various classes over the past several years. In particular, the technique has been used to study curing reactions in epoxies (12). polyimides (1), and acetylenic terminated sulfones (13). The ability to observe the evolution of the carbons of the reacting species has been clearly shown to provide valuable information which has been difficult or impossible to obtain with other techniques. The use of 13C solid state NMR techniques is essential for the understanding of curing reactions in high temperature polymers in order to be able to correlate the reaction chemistry with the structural and resulting physical properties. 

In the previous section it was suggested that the parent polymer structure considerably influence the physical properties of the derived polysulfonates, imparting to them some of the mechanical and thermal properties of the precursors. This trend is particularly evident in the case of the perfluorinated hydrocarbon polymers. Polymers of this kind, such as e.g., poly(tetrafluoroethylene) (PTFE) are exceptional in their inertness to offensive environment, solvent resistance and high-temperature stability. These considerations led in the sixties to the development of unique sulfonic-acid derivatives of fluorocarbon copolymers by the DuPont Company. While several compositions were disclosed in the patent literature51, the preferred composition, which is the basis for the commercial Nafion ion-exchange membrane, is a copolymer of tetrafluoroethylene with a perfluorinated vinyl ether/sulfonyl fluoride52 ... 

A variety of polymers are used in engineering and medical applications which have relatively little impact on the environment. These are mainly high performance and relatively expensive polymers such as the silicones in rubbers, the specialised polyamides referred to above in gear wheels, polycarbonates (in office equipment), chlorinated and sulfonated rubbers, fluorinated polymers such as poly tetrafluoroethylene) Teflon ) in metal coating and the polyimides which, owing to their ladder structure, are extremely stable in high temperature apphcations. Since these polymers are high-cost durable materials, they rarely appear in the waste stream. 

Polyether sulfone is a high-temperature engineering thermoplastic with the combined characteristics of high thermal stability and mechanical strength. It is a linear polymer with the following structure ... 

The investigation of different variants of sulfonated polyetherketones has been widely described in the literature polyetherketone [188], poly(ether ether ketone) [189-191], poly(ether ketone ketone) [192] and poly(ether ether ketone ketone) (sPEEKK) [193, 194], poly(oxa-p-phenylene-3,3-phthalido-p-phenylene-oxa-p-phe-nyleneoxy-phenylene) (PEEK-WC) [195]. An interesting comparison between different structures in this class of material (sulfonated poly (ether ether ketone) (sPEEK) and poly(phenoxy benzoyl phenylene)) (sPPBP) has been published by Rikukawa and Sanui [196]. Both polymers are isomers. In sPEEK the sulfonic groups are in the main chain, while in sPPBP they hang in a side chain. The water uptake at low relative humidity is higher for sPPBP as well as the conductivity at high temperatures. 

A suitable polymer material for preparation of carbon membranes should not cause pore holes or any defects after the carbonization. Up to now, various precursor materials such as polyimide, polyacrylonitrile (PAN), poly(phthalazinone ether sulfone ketone) and poly(phenylene oxide) have been used for the fabrication of carbon molecular sieve membranes. Likewise, aromatic polyimide and its derivatives have been extensively used as precursor for carbon membranes due to their rigid structure and high carbon yields. The membrane morphology of polyimide could be well maintained during the high temperature carbonization process. A commercially available and cheap polymeric material is cellulose acetate (CA, MW 100 000, DS = 2.45) this was also used as the precursor material for preparation of carbon membranes by He et al They reported that cellulose acetate can be easily dissolved in many solvents to form the dope solution for spinning the hollow fibers, and the hollow fiber carbon membranes prepared showed good separation performances. 

By using hydrophobic fluorinated polymer backbones, the phase separation can be made more distinct in phosphonated membranes, which in turn can enhance the proton conductivity. DesMarteau and co-workers have studied the proton transport characteristics of model perfluoroacid compounds functionalized with phosphonic, phosphinic, sulfonic, and carbo)q lic acids. The results indicated that the proton transfer in phosphonic and phosphinic acids occurs via structural diffusion rather than by a vehicle mechanism. The findings suggested that fluoroallqrlphosphonic and -phosphinic acids are good candidates for further development as anhydrous, high-temperature proton conductors. 

Carbon molecular sieves are prepared by the controlled pyrolysis of poly(vinylidene chloride) or sulfonated polymers (Carboxen ). They consist of very small graphite crystallites cross-linked to yield a disordered cavity-aperture structure. Carbon molecular sieves are microporous and of high surface area, 200-1200 m g . They are used primarily for the separation of inorganic gases, C1-C3 hydrocarbons, and for the separation of small polar molecules such as water, formaldehyde, and hydrogen sulfide. Less volatile compounds cannot be desorbed efficiently at acceptable temperatures. 

Polyether Sulfone (PES). Polyether sulfone is a transparent polymer with high temperature resistance and self-extinguishing properties. It gives off little smoke when burned. Polyether sulfone has the basic structure as shown in Fig. 2.39. 

The blend comprised at least two sulfone polymers, e.g., PES and PSF, and at least one non-sulfone polymer (e.g., PS, PPE, PEI, PC, PA, PEST, PP, or PE). The nucleating agent was either talc, mica, silica, Zn-stearate, Al-stearate, Ti02, or ZnO. The foams were used as insulation for high temperature structural applications. Since in the preceding part PPS blends with PSF were described, in Table 1.71 examples of PSF blends with other specialty resins are listed. 

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. 

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