High-performance polymer systems

A variety of polymer compositions that use this type of polymerization chemistry can be envisioned. In addition to the polyarylate homopolymers that have been described in this chapter, random or block copolymers can be prepared with reasonable ease by the combination of different monomers or oligomers. These compositions can be designed to optimize thermal, mechanical, dielectric, or optical properties of a polymer system. Also, the trifluorovinyl ether functionality can be incorporated into other high-performance polymer systems with relative ease.34,35 The perfluorocyclobutane polyarylate chemistry is a versatile approach to the preparation of high-performance polymers, which is just beginning to demonstrate its utility. 

Colquhoum, H. M. Lewis, D. E Ben-Haida, A. Hodge, P. Ring-chain interconversion in high-performance polymer system. 2. Ring-opening polmerization-copolyetherification in the synthesis of aromatic poly(ether sulfones). Macromolecules 2003, 36, 3775-3778. 

In the manufacture of unsaturated polyester resins the polyester is synthesized and then diluted with a vinyl reactive monomer such as styrene (see POLYESTERS, UNSATURATED). A portion of the dibasic acid of the polyester is maleic or some other vinyl reactive diacid that can be polymerized with the styrene to yield a highly cross-linked, high performance polymer system. Other esters made with propylene glycol, dipropylene glycol, and tripropylene glycol are used as emulsifiers in foods, as plasticizers in polymer systems, and as part of acrylate resin systems. 

H. M. Colquhoun, D. F. Lewis, P. Hodge, A. Ben-Haida, D. J. Williams, and I. Baxter. Ring-chain interconversion in high-performance polymer systems. 1. [poly(oxy-4,4 -biphenyleneoxy-1,4-phenylenesulfony 1-1,4-phenyl-ene)] (Radel-R). Macromolecules, 35 6875-6882, 2002. 

Hodge P. Ring-chain interconversion in high-performance polymer systems. 2. 

A large number of high-performance polymer systems are formed by the condensation reactions of diamines, or diols with aromatic diacids, or their derivatives. These include commercially successful products such as aramids, polyimides, poly(imide-amides), and polyesters. While some of the monomers used in the production of these polymers are readily available and made in large quantities, it is becoming more common to use smaller quantities of speciality monomers to tailor the properties of the resultant polymers to suit a specific application. To address this need, chemistries using unconventional monomers are being explored to offer alternative routes to a variety of polymeric systems. 

In the last several years a variety of polymeric systems have been prepared using variations on this chemistry. Herein are described several approaches to high-performance polymer systems using palladium-catalyzed polymerization... 

This section presents catalytic systems that have been studied for either the syndiesis of monomers or polymerization. In addition, some new catalysts, working in smoodi conditions, which could be used for high-performance polymers syndiesis are discussed. 

The number of such examples, however, is not high. In many other examples of advanced-performance materials, such as DuPont s Kevlar and Allied Signal s SPECTRA, the volume applications associated with system-for-system substitution has not yet occurred at a level necessary to pay back the development and commercialization costs already expended. High-performance ceramics is another area in which the early promise has yet to materialize. The consequences of Eckstut s life-cycle dynamics have been overcapacity and severe rationalization in high-performance carbon fiber businesses, some specialty alloy activities, and high-performance polymer composites. Thus, with critical technologies that involve advanced-performance materials, we need to better understand how to exploit their value in a commercially viable way. 

In the late 1970s, Kirchhoff at Dow Chemical Company developed the use of benzocyclobutenes in polymer synthesis and modification. These efforts culminated in 1985 with the issuance of the first patent describing the use of benzocyclobutene in the synthesis of high-molecular-weight polymer.27 Similar work that involved a thermosetting system based on Diels-Alder cycloaddition between terminal benzocyclobutene and alkyne groups,28,29 was reported separately and independently by Tan and Arnold.28 Since these initial discoveries, the field of benzocyclobutene polymers has expanded rapidly and benzocyclobutene chemistry constitutes the basis of a new and versatile approach to the synthesis of high-performance polymers for applications in the electronics and aerospace industries.30... 

Sulfonated poly(arylene ether)s have shown promise for durability in fuel cell systems, while poly-(styrene)- and poly(imide)-based systems serve as model systems for studying structure-relationship properties in PEMs because their questionable oxidative or hydrolytic stability limits their potential application in real fuel cell systems. Sulfonated high performance polymer backbones, such as poly(phe-nylquinoxaline), poly(phthalazinone ether ketone)s, polybenzimidazole, and other aromatic or heteroaromatic systems, have many of the advantages of poly-(imides) and poly(arylene ether sulfone)s and may offer another route to advanced PEMs. These high performance backbones would increase the hydrated Tg of PEMs while not being as hydrolytically sensitive as poly(imides). The synthetic schemes for these more exotic macromolecules are not as well-known, but the interest in novel PEMs will surely spur developments in this area. 

Of all the high temperature, high performance polymers, the benzobisazole rigid-rod polymers are one of the most thermally stable systems known. A variety of thermal techniques have been used to investigate their stability such as thermal gravimetric analysis (TGA), thermal gravimetric-mass spectrometry (TG-MS) and isothermal aging studies. A TGA plot shown in Fig. 4 is indicative... 

Carbopol resins are also suitable for highly-built systems SOURCE B.F. Goodrich Co. CARBOPOL High Performance Polymers ... 

Whereas UL 94 delivers only a classification based on a pass-and-fail system, LOI can be used to rank and compare the flammability behavior of different materials. In Figure 15.2 the increasing LOI values are presented for different polymers as an example POM = poly(oxymethylene), PEO = poly(ethyl oxide), PMMA = poly(methyl methacrylate), PE = polyethylene), PP, ABS, PS, PET = polyethylene terephthalate), PVA = poly(vinyl alcohol), PBT, PA = poly(amide), PC, PPO = poly(phenylene oxide), PSU, PEEK = poly(ether ether ketone), PAEK = poly(aryl ether ketone), PES, PBI = poly(benzimidazole), PEI = poly(ether imide), PVC = poly(vinyl chloride), PBO = poly(aryl ether benzoxazole), PTFE. The higher the LOI, the better is the intrinsic flame retardancy. Apart from rigid PVC, nearly all commodity and technical polymers are flammable. Only a few high-performance polymers are self-extinguishing. Table 15.1 shows an example of how the LOI is used in the development of flame-retarded materials. The flame retardant red phosphorus (Pred) increases... 

Klug, J. H., Model High Performance Adhesive Systems, Journal of Applied Polymer Science, vol. 66,1997, pp. 1953-1963. 

In the area of high-performance polymers there is a still growing market interest in sophisticated building blocks bearing multiple carboxylic functionalities on aromatic systems, the latter often being connected by flourinated spacer groups as in... 

The chemiluminescence test may require many hours, especially when performed at relatively low temperatures and applied to the analysis of highly stabilized polymer systems. Thus, the productivity of the instruments used was low and could not satisfy the demands. 

The objective of this Section is to raise the level of awareness that color needs to be part of any total systems approach to material design. We will survey the major classes of colorants suitable for use in high performance polymer blends and alloys and describe some of the potential chemical and physical colorant/material interactions. 

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