Polybenzimidazole commercial

The importance of proper RO membrane selection has already been discussed. A review of commercially available RO membranes revealed five different basic membranes that could provide organic recovery. Cellulose acetate and cellulose acetate blends, aromatic polyamide, polyamide thin-film composite, cross-linked polyimine thin-film composite (FT-30), and polybenzimidazole were available when this work was performed. Only the first four types were commercially available. All membranes were available with excellent salt rejection (>97 sodium chloride). Two types of membranes, cellulose acetate and FT-30, have shown short-term (<2-months intermittent use) resistance... 

More recently, we have seen other new plastics arrive, including such exotic, high performance materials as the polybenzimidazoles, polyoxadiazoles, polyperfluorotriazines, polyphenylenes, and such inorganic materials as the boron polymers, the metalloxanes, and the polysilazanes, to name only a few. These exotic materials are mostly development products today, they are very expensive and will undoubtedly find their first uses, if any, in the aerospace industry which requires the high performance offered by these materials and can afford to pay for them. Some of these new materials will become commercial successes, others will not. 

POLYBENZIMIDAZOLES. These are heterocyclic polymers that have outstanding high thermal characteristics, the highest obtainable in commercial polymers. These materials also have superior ablative and hydrolytic stability as well as high compressive and dimensional stability. Polybenzimidazoles essentially arc unaffected by solvents, acids, and bases. They are marketed in stock shapes and as finished parts. The materials are not available in resin form Hoechst Celanese markets tile products under tile tradename Celazole, ... 

Other membrane materials include mainly polyimide, polyacrylonitrile and polybenzimidazole. An overview of commercially available membranes is given in Table 3.2. These membranes are manufactured in procedures usually derived from practical experience by using high-throughput screening, it was shown that optimization is possible [26]. Many other membrane materials are described in the scientific literature and in patents an overview is given by Cuperus and Ebert [27]. 

Poly-2-2 -(w-phenylene)-5,5 -bibenzimidazole, commonly called polybenzimidazole (PBI), was developed under the aegis of the U.S. Air Force Materials Laboratory in cooperation with the then-existing Celanese Corporation. The fiber went into commercial production in the United States in 1983. It is a condensation polymer obtained from the reaction of tetra-aminobiphenyl and diphenylisophthalate in a nitrogen atmosphere at temperatures that may reach 400°C in the final stages.29 The structure of a repeating unit is shown below. 

In summary, the polybenzimidazole story reviewed in the foregoing sections reflects a vast research effort indeed, accomplished over the years in numerous polymer laboratories. A wide ran of direct and two-stage synthetic approaches is now available to the polymer chemist, and an equally wide scope of challenging possibilities of application has opened up to the technologist. It should also be clear from the presented material, however, that tte stage of commercial maturity has not as yet been attained, and intriguing new developments both on the preparative side and in the application s[Aere can, therefore, with confidence be expected in the years to come. 

Polybenzimidazole (PBI) has been suggested as a useful polymer candidate for PEMFCs on the basis of its excellent thermochemical stability and mechanical properties. Commercially available PBI has a Tg of 425-435 °C, and shows a longterm thermal stability above 350 °C. As shown in Figure 10.8, PBI is a basic polymer... 

Of the fibers listed in Table II only the polyesters, polyamides, spandexes, acetates, and rayon are discussed in this chapter. While the acrylics and modacrylics are the third most important class of commercial fibers because their polymerization chemistry is also discussed in other chapters concerned with vinyl addition emulsion polymerizations, it will only be briefly summarized here. For the same reason polypropylene polymerization chemistry is also not covered in this section. However, two additional topics, carbon fiber formation and polybenzimidazoles have been included on the basis of the current Interest in high-performance fibers for composite materials. 

Additional polymer blends comprising PAEK s offering property combinations of potential utility include PSF [Robeson and Harris, 1986 Harris and Robeson, 1989] structurally different poly(aryl ketones) [Harris and Robeson, 1986], PAr [Robeson and Harris, 1992], poly(amide-imide) PAI [Harris and Gavula, 1992], PPS [Robeson, 1987], and other PI [Harris et al., 1992]. Mixtures of structurally different PAEK s were noted to be isomorphic within specific limits of ether/ketone ratios [Harris and Robeson, 1987]. Blends of polybenzimidazole, PBI and several commercial PI (Ultem 1000 and Matrimid 5218) have been studied in depth at the University of Massachusetts and found to be miscible. FTIR studies [Guerra et al., 1988 Kim et al., 1993], NMR studies [Grobelny et al., 1990], thermal, dielectric, and mechanical... 

U.S. Air Force research program began toward the end of his first career at the University of Illinois and continued throughout his entire second career at the University of Arizona. During a 30-year period he was the principal contributor to the Air Force program on high temperature polymer synthesis. His basic research led to the commercialization of polybenzimidazole (PBI)... 

Polymer blends leading to high-end polymers, e.g. from sulfonated polymers (sPEEK - sulfonated polyether-etherketone, sPPSU - sulfonated polyphenyl-sulfone) combined with alkaline components (amine, imidazole, polybenzimidazole) The combination results in ionic cross-linked phases. Commercially available polymers can be modified by different sulfonation reagents. Another possibility is to combine different monomers based on block co-polymers. The conductivity can be controlled by the number of S03H groups due to the dependence of the water uptake from the number of groups ([23] and references cited therein). 

Polybenzimidazole (PBI) is the most well-known commercial example of aromatic heterocycles used as high-temperature polymers. The synthesis of PBI is carried out as follows (see also Figure 1.36). The tetraaminobiphenyl required for the synthesis of PBI is obtained from 3,3 -dichloro-4,4 -diaminodi-phenyl (a dye intermediate) and ammonia. Many other tetraamines and dicarboxylic acids have been... 

Commercial polymers based on the principle of synthesis of polyaromatic compounds include the previously discussed commercial polymers—aromatic polyamides, polyimides, polyfphenylene oxide), polysulfone, and polybenzimidazole (see Chapter 4). 

Sulfonated aromatic polymers have been widely studied as alternatives to Nafion due to potentially attractive mechanical properties, thermal and chemical stability, and commercial availability of the base aromatic polymers. Aromatic polymers studied in fuel cell apphcations include sulfonated poly(p-phenylene)s, sulfonated polysulfones, sulfonated poly(ether ether ke-tone)s (SPEEKs), sulfonated polyimides (SPIs), sulfonated polyphosphazenes, and sulfonated polybenzimidazoles. Representative chemical structures of sulfonated aromatic polymers are shown in Scheme 3. Aromatic polymers are readily sulfonated using concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, or sulfur trioxide. Post-sulfonation reactions suffer from a lack of control over the degree and location of functionalization, and the... 

These fibre-formimg polymers are so-called ladder polymers and possess wholly aromatic polymer chains. The two common examples available commercially are the polybenzimidazole FBI (Intertek, formerly Celanese) with the full chemical name poly (2,2 -(m-phenylene)-5,5 -bibenzimidazole) and the polybenzoxazole Zylon (Toyobo) with the full chemical name polyfpara-phenylene benzobisoxazole) and generic acronym PBO. Their similarity in polymer chain stractures and high degrees of... 

The polyaromatic resins, polyimide and polybenzimidazole, offer greater thermal resistance than any other commercially available adhesive. The rigidity of their molecular chains decreases the possibility of chain scission caused by thermally agitated chemical bonds. The aromaticity of the... 

Although in certain respects the polybenzimidazoles offer a virtually unique combination of properties, they have not enjoyed the success of other High-temperature adhesives. A major reason for this has undoubtedly been due to the monomeric materials required, most notably aromatic tetraamines, being both costly and difficult to obtain in the required purity. In addition, doubts concerning carcinogenic activity have also been expressed (see Health and safety), which, together with the adverse processability mentioned above has severely restricted their acceptance. For these reasons, commercial availability has to date been somewhat limited. 

These fibre-forming polymers are so-called ladder polymers and are essentially wholly aromatic polymer chains. The two examples commonly available commercially are the polybenzimidazole PBI (Celanese) with the full... 

S. K. (2006) Experimental characterization and modeling of commercial polybenzimidazole-based MEA performance. J. Power Sources, 162, 239. 

The use of adhesives can be traced back many centuries, while the production of adhesives, on an industrial scale, started about 300 years ago. The birth of modern structural adhesives can be dated from about 1910, with the introduction of the phenol-formaldehyde resins.Table II summarizes the historical development of structural adhesives, with the dates referring to the approximate time period during which each adhesive became commercially available. The introduction dates for the high-temperature polymers (polyimide, polybenzimidazole, and polyquinoxa-line) have been included for reference, although, as previously mentioned, there are presently few commercial products based on these polymers. 

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