Vinyl chloride structure

Essentially, a membrane transport cell is used with oxidant on one side and monomer solution on the other. Where polymerization occurs depends on the relative mobility of the oxidant and the monomer. In fact, this can be used to localize conducting polymer formation within the membranes. For example, with a nation membrane and the use of S20g as oxidant, polymerization is restricted to the oxidant side of the membrane due to anion exclusion (nation is negatively charged). When Fe is used as oxidant, polymerization occurs throughout the membrane. The use of different solvents can also affect the transport processes for oxidant and monomer. This was used to fix the point of polymerization by other co-workers who prepared PPy-poly(vinyl chloride) structures. Similar procedures have been used to coat PPy onto cellulose acetate and PYC. ... 

Poly(vinyl chloride) as previously discussed in Sec. 10.3, Formulas and Key Properties of Plastic Materials, has the following structures ... 

Structural Components. In most appHcations stmctural foam parts are used as direct replacements for wood, metals, or soHd plastics and find wide acceptance in appHances, automobUes, furniture, materials-handling equipment, and in constmction. Use in the huil ding and constmction industry account for more than one-half of the total volume of stmctural foam appHcations. High impact polystyrene is the most widely used stmctural foam, foUowed by polypropylene, high density polyethylene, and poly(vinyl chloride). The constmction industry offers the greatest growth potential for ceUular plastics. 

Much work has been carried out in order to elucidate the molecular structure of poly(vinyl chloride). In 1939, Marvel, Sample and Roy dechlorinated PVC with zinc dust to give linked cyclic structures (Figure 12.9). 

X-ray studies indicate that the vinyl chloride polymer as normally prepared in commercial processes is substantially amorphous although some small amount of crystallinity (about 5% as measured by X-ray diffraction methods) is present. It has been reported by Fuller d in 1940 and Natta and Carradini in 1956 that examination of the crystalline zones indicates a repeat distance of 5.1 A which is consistent with a syndiotactic (i.e. alternating) structure. Later studies using NMR techniques indicate that conventional PVC is about 55% syndiotactic and the rest largely atactic in structure. 

In addition to homopolymers of varying molecular and particle structure, copolymers are also available commercially in which vinyl chloride is the principal monomer. Comonomers used eommercially include vinyl acetate, vinylidene chloride, propylene, acrylonitrile, vinyl isobutyl ether, and maleic, fumaric and acrylic esters. Of these the first three only are of importance to the plastics industry. The main function of introducing comonomer is to reduce the regularity of the polymer structure and thus lower the interchain forces. The polymers may therefore be proeessed at much lower temperatures and are useful in the manufacture of gramophone records and flooring compositions. 

Epoxidised drying oils have been available for several years as stabilisers for poly(vinyl chloride). They may be considered to have the skeletal structure shown in Figure 26.17. 

From the results obtained by thermal decomposition of both low-molecular weight vicinal dichlorides in the gas phase [74,75] and of the copolymers of vinyl chloride and /rthermal instability of PVC to the individual head-to-head structures. Crawley and McNeill [76] chlorinated m-1,4-polybutadiene in methylene chloride, leading to a head-to-head, and a tail-to-tail PVC. They found, for powder samples under programmed heating conditions, that head-to-head polymers had a lower threshold temperature of degradation than normal PVC, but reached its maximum rate of degradation at higher temperatures. 

Draw a line-bond structure for vinyl chloride, C2H3CI, the starting material from which PVC [polyfvinyl chloride)) plastic is made. 

Show the structure of poly(vinyl chloride), a polymer made from H C CHCl, by drawing several repeating units. 

C2F4 displaces one ethene to give Rh(C2H4)(C2F4)(acac), as does hexa-fluorodewarbenzene, whereas other alkenes (e.g. propene, styrene, vinyl chloride) displace both ethenes. Comparison of the structures of two complexes (Figure 2.28) shows that the Rh-C bonds are shorter to tetra-fluoroethene, because C2F4 is a better 7r-acceptor, with concomitant strengthening of the Rh-C bond. 

Thus, a polyester with the ring in the backbone can be prepared by the Friedel-Crafts polyalkylation of vinyl 2-furoate. BF3 Et20 gave similar results at room temperature in methylene chloride. Structure 30 was arrived at by spectroscopy and by alcoholysis of the polymers. 

We might predict that of the six chloroethylenes the C-Cl distance would be smallest in vinyl chloride, which resonates between the structures... 

The first three telomers CCl2Br(CH2CHCl)nBr (n = 1 - 3) were isolated as individual compounds, the structure was confirmed by NMR spectroscopic data. The values of the chain transfer partial constants (Cj = 7 C2 = 54.3) point to the high efficiency of CBr2Cl2 as a chain transfer agent, which comparable with that of CBr4 (C2 = 74.2) (in the similar reaction with vinyl chloride) (ref. 7). 

C13-0004. The polymer known as PVC is used to make plastic pipes. The monomer used to make PVC is vinyl chloride. Draw a segment of the PVC polymer containing four repeat units. See Figure 13-3 for the structure of vinyl chloride. 

C13-0048. Saran is a copol3Tner made from vinyl chloride and vinylidene chloride (H2 C I CCI2). Draw the structure of this polymer, showing at least four repeat units in the polymer. 

Multiple pathways leading to the same product channel can also be observed in a reaction when there are a sufficient number of identical atoms, thereby allowing different intermediate structures to yield the same products. In these cases, the mechanisms in the two pathways are often quite similar, but involve differing positions of identical atoms on the reactants. The different pathways often involve formation of ring intermediates in which the rings have different sizes. A simple example of this class is the photodissociation of vinyl chloride [9]... 

Marvel, Sample, and Roy concluded that cyclopropane rings were formed when a dilute solution of poly-(vinyl chloride) in dioxane was treated with zinc, which removes halogen atoms from alternate carbon atoms. Only 84 to 86 percent of the chlorine could be removed, however, a result which was attributed to the occasional isolation of a lone substituent between reacted neighbors. The structure of the product was presumed to be... 

Carbonyl Groups. Such structures could be introduced by air oxidation during polymerization or subsequent processing of the polymer. There is, in fact, some experimental evidence for their formation during polymerization via the following sequence of steps (6) (1) copolymerization of vinyl chloride with adventi-... 

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