Poly , repeat unit structure

The most common silicone fluids arc based on poly(dimethyl siloxane) with the repeating unit structure ... 

There are also a few common polymers whose accepted names convey relatively little information about the repeating unit structure. The primary examples are polycarbonate, poly(phenylene oxide), polyamide-imides, poly-sulfones, and polyether ketones (see Table 1.3). 

Figure 11.2. Calculation of a rough estimate for the length of a polymeric repeat unit in its fully extended conformation, with poly(methyl methacrylate) as the example, (a) The repeat unit structure. The distance defined as lm is shown, (b) Use of simple trigonometry (i.e., the...

The other major member of this grouping is the poly (aramid-arimid) fibre Kermel , which was produced initially by Rhone-Poulenc of France in 1971 and since 2007 has been an independent company, Kermel (France). It has the polymer repeat unit structure ... 

The remarkable properties of "TEFZEL" ETFE are best illustrated by comparison with the isomeric polydifluoroethylene. This difference can be thought of as the result of a difference in repeat unit structure. In fact, there is a remarkable similarity between ETFE and poly-1, 1, 4, 4-tetrafluorobutadlene in both chemical and physical properties, including nearly identical crystalline melting points. 

Isomerization of Polymeric P-Chlorosulfides. The first example of a repeating unit isomerization was found when we examined the carbon-13 NMR spectrum of a sample of poly(chloromethyIthiirane) which had been stored at room temperature for three months. Instead of the expected three lines at approximately 39, 51 and 54 ppm down-field from tetramethylsilane, we foimd two major lines at 40 and 61 ppm the expected signals were present, but of low intensity. The proton NMR spectrum was also unexpected, showing in addition to the backbone and chloromethyl signals, a downfield (6 4.28) quintet which could not be rationalized on the basis of the simple CMT repeating unit structure. When a freshly-prepared sample was analyzed, both the and the NMR spectra were as predicted. 

Polyether ether ketone (PEEK) is a linear, aromatic, semi-crystalline thermoplastic possessing excellent thermal stability, chemical resistance and mechanical properties under engineering applications. It has the repeating unit structure, 0—Ph—O—Ph—CO Ph—, wherein "Ph" is the 1,4-phenylene unit. Its true scientific name is poly (oxy-1, 4-phenylene-oxy-l, 4-phenylenecarbonyl-l, 4-phenylene). The polymer is featured in a wide range of applications including transportation, energy, industrial, electronics, semiconductor and medical. 

Figure 6.17 Repeating unit structures of (a) poly(p-phenylene terephthalamide) (Kevlar) (b) copolyester of p-hydroxybenzoic acid and ethylene terephthalate (c) copolyester of p-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid (Vectra).

The history of polymers, including the beginning of addition and of radical polymerization, is recormted by Morawetz. The repeat unit structure (1) of many common polymers, including polystyrene (PS), poly(vinyl chloride) (PVC), and poly(vinyl acetate) (PVAc), was established in the latter half... 

Concept Check 14.2 On the basis of the structures presented in the previous section, sketch the repeat unit structure for poly (vinyl fluoride). 

Figure 11.1 Repeat unit structures of polybutadiene and its hydrogenation product poly (ethylene-cu-1-butene) and polyisoprene and its hydrogenation product poly(ethylene-u/t-propylene).

Poly(butylene Terephthalate). Poly(butylene terephthalate) is prepared in a condensation reaction between dimethyl terephthalate and 1,4-butanediol and its repeating unit has the general structure... 

It has been observedt that poly(1,1-dimethyl propane) is the product when 3-methylbutene-l is polymerized with AICI3 in ethyl chloride at -130°C. Write structural formulas for the expected repeat units and those observed and propose an explanation. 

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