High-temperature polymer poly

Over the past 20 years a considerable chemical research effort was devoted to developing new high temperature polymers. It is interesting to note that some of these materials are now finding new applications and solutions to old problems of processing through blending. A commercial series of products trade-named Tribolon XT has been announced which are based on an aromatic polymide (Upjohn s 2080) with Phillips poly(phenylene sulfide), trade-named Ryton. A recent publication (88) describes some of the unique characteristics of this new family of materials. 

In Table 1, the moisture uptake of cured and uncured Navy P3-2300-PE resin after 24 hours of immersion is compared to a number of other high-temperature polymer resins. The moisture uptake of the Navy P3 oligomer is nearly identical to that of the commercial P3 thermoplastic. Other commercial thermoplastics, such as poly(ether ether ketone), with very similar chemical compositions, exhibit similarly low levels of moisture uptake. On the other hand, the Navy P3 resins absorbs about 85% less water than the commercial polyimide Kapton HN. Since thermosetting phenyl ethynyl end-capped polyimides have moisture uptake characteristics that are similar to Kapton HN, with around 3% weight gain on exposure to 95% relative humidity (77), void-free composites based on Navy P3 resins should exhibit greatly reduced moisture uptake compared to those based on thermosetting polyimides. 

Quinoxaline 1,4-dioxides possess antibacterial activity, " as well as being fungicides, insecticides, and herbicides. Quinoxaline-2-carboxylic acid 1,4-dioxide has been isolated from cultures of Sireplomyces ambrofaciens and this compound has been shown to have antibiotic properties. Echinomycin, from the quinoxaline-peptide antibiotic family, contains one or more quinoxaline rings and is an antitumor agent. Quinoxaline derivatives are also antagonists at the jV-methyl-D-aspartate (NMDA) receptor of the glycine modulatory site. Poly(phenylquinoxalines) are used as high temperature polymers. 

Kevlar, or aramid as it is generically known, is a highly oriented polymer - poly(p-phenylene terephthalamide). Kevlar fiber has the interesting property of having a linear TCE in its axial direction of -2 x 10 6/°C. The E-glass used in normal PWBs has a positive linear TCE of +5 x 10-room temperature TCEs in the X-Y plane of around 4 to 8 x 10 6/ C(3) and solder joint cracking is greatly reduced or eliminated(2). Quartz is another reinforcement, available in fabric form, which can be used to control the planar TCEs of a laminate PWB. Quartz has a TCE of +0.54 x 10-6/°C in the axial direction. 

The homopolymer of HBA was first successfully prepared in 1963 by Economy and coworkers at Carborundum Co. (Economy, 1989). The goal was to prepare new types of high temperature polymers that were proces-sible by techniques such as compression sintering developed at Carborundum rather than by expensive solution processes normally used for high temperature polymers. By carefully designed polymerizations of phenyl 4-hydroxybenzoate, they were able to synthesize poly(4-hydroxybenzoate). The product was very stable in air even up to 400 °C and could be compression sintered at 400 °C under 10,000 psi to yield specimens with a flexural... 

Poly(aryl ketones) (PEEK, PEK, and PEKK) are commercial high temperature polymers offering an excellent combination of properties combined with thermoplastic behavior. Poly(aryl ether ketone) PAEK blends have been reviewed by Harris and Robeson [1989]. Miscibility with PEI (Ultem 1000 GE) and other PI containing isopropylidene bridging units was noted. Arzak et al. [1997] reviewed the performance ofPEEK/PEI blends and noted a synergistic behavior in ductility and impact strength as reported earlier. Utility of these blends as a thermoplastic matrix candidate for advanced composites has been proposed [Harris and Robeson, 1989 Davis et al., 1992]. 

Asensio JA, Gomez-Romero P (2005) Recent developments on proton conducting poly (2,5-benzimidazole) (ABPBI) membranes for high temperature polymer electrolyte membrane fuel cells. Fuel Cells 5 336-343... 

Wannek C, Lehnert W, Mergel J (2009) Membrane electrode assemblies for high-temperature polymer electrolyte fuel cells based on poly (2,5-benzimidazole) membranes with phosphoric acid impregnation via the catalyst layer. J Power Sources 192 258-266... 

Yurchenko ME, Huang J, Robisson A, McKinley GH, Hammond PT. Synthesis, mechanical properties and chemical/solvent resistance of crosshnked poly(aryl-ether-ether-ketones) at high temperatures. Polymer 2010 51(9) 1914-20. 

Wang YF, Hsu T, Hay AS, Li K, Patel B. High temperature polymer blends of poly(aryl ether ketone phthalazinone). US Patent Application 20110104417, assigned to Polymics Ltd., State College, PA 2011. 

Lee HJ, Lee DH, Henkensmeier D, Jang JH, Cho EA, Kim HJ, et al. Synthesis and characterization of H3PO4 doped poly(benzimidazole-co-benzoxazole) membranes for high temperature polymer electrolyte fuel cells. Bull Korean Chem Soc 2012 33(10) 3279-84. 

Studies of uniaxial extension on noncrystallizable elastomer, poly(phenyl methyl siloxane) showed results which are consistent and comparable with those obtained for PDMS, suggesting that the crystallization is not important for this type of reinforcement [20]. Other examples for reinforcement effects achieved with the addition of silica fillers include polyisobutylene [24], poly(ethyl acrylate) [3], poly (tetra methylene oxide) [29,30], and some high-temperature polymers such as aromatic polyamides [14,33,34], polyi-mides [15,38,39], polybenzoxazoles [16,17], and polyben-zobisthiazoles [16,17]. Results indicated that the modulus increases with increase in silica content while the tensile... 

Urethanes are not high temperature polymers. Continuous service applications at more than about 100°C are not recommended. They are subject to hydrolysis other materials should be considered in applications which involve long-term continuous immersion in water. They undergo autoxidation on thermal or ultraviolet activation. Poly(ester-urethanes) are subject to microbiological degradation. 

Bakelite was a thermoset that is, it did not flow after the synthesis was complete (20). The first synthetic thermoplastics, materials that could flow on heating, were poly(vinyl chloride), poly(styrene-5t t-butadiene), polystyrene, and polyamide 66 see Table 1.8 (20). Other breakthrough polymers have included the very high modulus aromatic polyamides, known as Kevlar (see Section 7.4), and a host of high temperature polymers. 

J.K., and Pojman, J.A. (2000) Gas-free initiators for high-temperature polymerization. /. Poly. Sd., Part A Polym. Chem., 38, 3984-3990. 

Chang-Chung Yang, Kuo Huang Hsieh and Wen-Chang Chen (2003) "A new interpretation of the kinetic model for the imidization reaction of PMDA-ODA and BPDA-PDA poly(amic acid)s". In Polyimides and Other High Temperature Polymers, Vol. 2. K.L. Mittal editor. VSP. pp. 37-45. 

Berber MR, Fujigaya T, Sasaki K et al (2011) Remarkably durable high temperature polymer electrolyte fuel cell based on poly(vinylphosphonic acid)-doped polybenzimidazole. Sci Rep 3 1-7... 

Yuan S, Guo X, Aili D et al (2014) Poly(imide benzimidazole)s for high temperature polymer electrolyte membrane fuel cells. J Membr Sci 454 351-358... 

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