Aromatization, temperature programmed studies

Bridie et al. [27] have studied the solvent extraction of hydrocarbons and their oxidative products from oxidised and non-oxidised kerosine-water mixtures, using pentane, chloroform and carbon tetrachloride. Extracts are treated with Florasil to remove non-hydrocarbons before analysis by temperature programmed gas chromatography. From the results reported it is concluded that, although each of the solvents extracts the same amount of hydrocarbons, pentane extracts the smallest amount of non hydrocarbons. Florasil effectively removes non hydrocarbons from pentane extracts, but also removes 10-25% of aromatic hydrocarbons. However, as the other solvents are less susceptible than pentane to treatment with Florasil, pentane is considered by those workers to be the most suitable solvent for use in determining oil in water. 

Originally. TOA was devised and used for analyses of chain mobility in polymers (7) and polymer blends (8.91 by monitoring birefringence disappearance during programmed heating in scratches scribed on film surfaces. Lenz (10.Ill has reported the use of TOA in the study of liquid crystal polymers, and recently we have used the technique in determining melt- and isotropization temperatures for thermotropic fully aromatic liquid crystal polymers (4.51. 

Polybenzimidazoles first appeared in US Patent 2,895,948 in 1959. In 1961, Vogel and Marvel opened the field of high temperature polymers [1] with their studies of the thermal stability of aromatic polybenzimidazoles [3]. Subsequently, AFML and NASA funded programs for basic studies and for structural and textile applications of polybenzimidazoles to meet new aircraft and aerospace material needs. Several reviews were published [4-7]. Structural applications of polybenzimidazoles are still in developmental stages which is discussed below. One polybenzimidazole polymer (PBI) which was developed for fiber applications is now commercial. Details of the polymer synthesis and fiber process are described in the next section. 

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