Polymers High performance

In developing tough, heat-resistant polymers the chemists pursued several goals. These were  

To develop new macromolecules based on chemical structures capable of withstanding high temperatures. 

To develop inorganic and inorganic-oiganic polymeric materials, because many inoiganic molecules are more thermally stable than the organic ones. 

To improve heat stability of the available polymers by introducing structural modifications. 

The development of high performance polymers, such as high performance plastics, high 

In many cases, unique optical textures are observed for the various orientations and structures of the three classes of liquid crystals. Thin films of nematic crystals, for example, can be identified by the pattern of dark threads (isogyres) that can appear in the optical microscope in transmission with crossed polar- 

There are thousands of LCPs that can be considered in three commercially important classes  

High modulus fibers from lyotropic aromatic polyamides, poly(p-phenylene terephthalamide) (PPTA), first commercialized under the Kevlar trademark by DuPont [614], find major applications as fibers in tire cords and heat and chemical resistant fabrics. Other fibers in this class of materials are used in important applications such as firefighter and military uniforms, gloves, and in many other hazardous applications. The aromatic polyamides, or aramids, are produced by a dry jet-wet spinning process where the nematic structure in solution is responsible for the high modulus fiber performance [615-619]. Another class of lyotropic fibers, also produced by dry jet-wet spinning, are the rigid-rod 

Optical microscopy, SEM, and TEM studies of TLCPs have been reported (e.g., [612, 613]. 

The driving force in polymer synthesis is the search for new polymers with improved properties to replace other materials of construction. Polymers are lightweight and can be processed easily and economically into a wide range of shapes and forms. The major synthetic efforts at present are aimed at polymers with high temperature, liquid crystal, conducting, and nonlinear optical properties [Maier et al., 2001 Sillion, 1999]. There is an interrelationship between these efforts as will become apparent. 

Title Phenol-Formaldehyde Resins Having Low Concentration of Tetradimer 

Patent Application Material Patentability Anticipated Issuing Date  

Research Focus Method for minimizing the formation of phenol-formaldehyde tetramers in phenol-formaldehyde condensation reactions. 

Originality The use of sodium sulfite as an agent to lower tetramer formation in 

Observations In the process of preparing novolak resins, phenol-formaldehyde tetramer 

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The value of many chemical products, from pesticides to pharmaceuticals to high performance polymers, is based on unique properties of a particular isomer from which the product is ultimately derived. Eor example, trisubstituted aromatics may have as many as 10 possible geometric isomers whose ratio ia the mixture is determined by equiHbrium. Often the purity requirement for the desired product iacludes an upper limit on the content of one or more of the other isomers. This separation problem is a compHcated one, but one ia which adsorptive separation processes offer the greatest chances for success. 

For fluorine-free products, the labiUty of fluorine in fluoronitrobenzenes and other activated molecules permits it to serve as a handle in hair-dye manufacturing operations, high performance polymers such as polyetheretherketone (PEEK), production of dmgs such as diuretics, and fiber-reactive dyes. Labile fluorine has also been used in analytical appHcations and biological diagnostic reagents. 

Another commercial appHcation of nucleophilic reactions of nitro-free duoroaromatics is the manufacture of polyetheretherketone (PEEK) high performance polymers from 4,4 -diduoroben2ophenone [345-92-6], and hydroquinone [121-31-9] (131) (see PoLYETHERS, AROMATIC). 

Carboxyhc acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthahc acid [88-99-3J, react with aryl isocyanates to yield the corresponding A/-aryl phthalimides (73). Reactions with carboxyhc acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature appHcations where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

Small amounts of polymer-grade terephthaHc acid and dimethyl terephthalate are used as polymer raw materials for a variety of appHcations, eg, adhesives and coatings. They are also used to make high performance polymers or engineering resins. Poly(ethylene terephthalate) is itself an engineering resin, although one more widely used is poly (butylene) terephthalate, formed by reaction with 1,4-butanediol as the comonomer. 

High Performance Polymers Their Origin and Development," Proceedings of the ACS Symposium, Neiv York, Apr. 15—18, 1986, Elsevier Science Pubhshing Co. Inc., New York, 1986. 

The data reported are permeabilities, not fluxes. Fhix is propor-TABLE 22-27 High-Performance Polymers for O /N ... 

Robeson []. Membrane ScL, 62, 165 (1991) Polymer, 35, 4970 (1994)] has determined upper-bound hnes for many permeant pairs in hundreds of polymers. These hnes may be drawn from Eq. (22-109) and the data included in Table 22-28. These values will give in Barrers a is dimensionless. Robeson [op.cit., (1991) op. cit., (1994)] hsts high-performance polymers for most of these gas pairs, hke Table 22-28. 

The polyetherimides are competitive not only with other high-performance polymers such as the polysulphones and polyketones but also with polyphenylene sulphides, polyarylates, polyamide-imides and the polycarbonates. 

Seymour, R.B. and Kirshenbaum, G.S. (1986) High Performance Polymers Their Origin and Development (Elsevier, New York). 

Vaidyanathan, R., and EI-Halwagi, M. M. (1994). Computer-aided design of high performance polymers. J. of Elastomers and Plastics, 26, 277-293. 

New Generation High Performance Polymers by Displacement Polymerization... 

Recently, Dutta and Maiti [21] reported nitro displacement polymerization of the bisphenol dianion with the sulfone activated dinitro aromatic compounds. In addition, there have been recent reports of the development of functionalized PEEK [22] and polyether sulfone ketone (PESK) [23] that are comparable to commercially available high performance polymers. 

Phenothiophosphine ring-containing polyamides and polyesters were also prepared by the polycondensation of 2,8-bischloroformyl-lO-phenylphenothiophos-phine 5,5, 10-trioxide with aromatic diamines such as 4,4 -diaminodiphenyl ether and 4,4 -diaminodiphenyl-methane, and bisphenols such as 4,4 -dihydroxybiphe-nyl and 4,4 -dihydroxydiphenylmethane, respectively [159]. These polymers are soluble in polar aprotic solvents and also exhibit good heat and fire resistance. Phosphorus containing high performance polymers are shown in Table 6. 

Table 6 Phosphorus Containing High Performance Polymers...

P. M. Hergenrother, J. W. Connell, and P. Wolf, Proceedings of Symposium on Recent Advances in Polyim-ides and Other High Performance Polymers, ACS, San Diego, CA, USA, (1990). 

Although urushiol possesses an interesting structure for transformation into speciality polymers, no attempt has been reported. Notwithstanding its applications in a specified area, it appears that it is not properly put to use as it can be converted to polymers with better properties. The possibilities for such conversions into high-performance polymers are illustrated by cardanol, a phenolic lipid of related structure obtained from Ana-cardium occidentale. 

Characterization and control of interfaces in the incompatible polymer blends were reported by Fayt et al. [23]. They used techniques such as electron microscopy, thermal transition analysis, and nonradiative energy transfer (NRET), etc. They have illustrated the exciting potentialities offered by diblock copolymers in high-performance polymer blends. 

S. Dutta, High Performance Polymers (A. Fawcett, ed.). Royal Society of Chemistry, London, Chap. 2, p. 33 (1990). 

S. Nagai, K. Takemoto, H. Takahashi, M. Yoshida, and A. Ueda, IPST 94 lUPAC International Symposium Functional and High Performance Polymer, p. 641 (Taipei, 1994). 

Polyesters are one of the most versatile classes of polymers ever produced, covering a wide range of properties and applications. Polyesters are present in fibers, engineering thermoplastics, and high-performance polymers as well as in thermosetting resins and elastomers. Table 2.1 lists the chemical structure, abbreviations, and uses of some commercially important thermoplastic polyesters. 

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