Polyamides metalated with sodium

Sodium bicarbonate, with or without citric acid, is a blowing agent that decomposes endothermically at 150-230 °C. It is suitable for polystyrene, ABS, polyamides, the polyolefins and rigid PVC, but not plasticised PVC. The gases evolved include carbon dioxide and water, so there can be a rust problem with metal moulds. The type of foam obtained with sodium bicarbonate usually has a coarse structure, although tests with different manufacturers products, all using bicarbonate/citric acid as the active ingredient, show considerable differences in cell and foam density. 

In order to increase the solubility of the para wholly aromatic polyamide, PPTA, Katayose succeeded in producing the AT-substituted polyamide using a metalation reaction. The polyamide was reacted with a solution of sodium methylsulfinyl carbanion in DMSO this anion being formed from reaction of powdered sodium hydride with excess dry DMSO [67a] (Scheme 12). 

Carothers work included both, KC and TC polymerization, but neither he nor his coworker Rory realized and discussed this difference. Under the conditions used by Carothers, the syntheses of polyesters and polyamides were TC polycondensations, whereas the syntheses of polyalkanes from 1,10-dibromodecane and sodium metal were perfect KCPs (see Chap. 3). In 1950, Stockmayer and coworkers published two papers [1,2] which dealt with the formation of cylics in ring-chain equilibria during synthesis or thermal degradation of polymers. The first paper was focused on the calculation of distribution functions of the cyclic oligomers, whereas the second... 

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