Thermal decomposition of polystyrene,polyoxyethylene glycol and their mixtures by thermogravimetric techniques

The thermal decompositions of polystyrene, polyoxyethylene glycol and mixtures of the two have been studied by thermogravimetry. The composition of the mixtures both before and after decomposition, as well as changes in the molecular weights and polydispersities of the polystyrene components, were followed by gel permeation chromatography. Ultra-violet spectrophotometry also served to determine the polystyrene contents of the mixtures after decomposition. The presence of polyoxyethylene glycol as a reaction promoter was found to have a pronounced effect on the decomposition of polystyrene, believed to be initiated, in large part, by intermolecular transfer. The depolymerization that follows takes place more rapidly probably because of the presence of a large number of active fragments. The overall activation energy, calculated by the method of Flynn and Wall, supports this hypothesis, being lower in the presence of polyoxyethylene glycol and higher in its absence.     

Kationische Copolymerisation von Styroloxid mit Propylenoxid

Ohne Zusammenfassung     

Gas-liquid chromatographic separation of common amino acids in pine needle extracts

An improved gas—liquid chromatographic method based on the separation of N-trifluoroacetyl n-butyl esters of amino acids on a “two-column” setup --- Tabsorb and Tabsorb HAC --- was developed for the identification and estimation of amino acids in pine needles (Pinus banksiana Lamb.). A comparative study was made of various available gas—liquid chromatographic methods for separation and estimation of amino acids from pine needle extracts.     

Synthesis,spectral, fluorescence and thermal studies on ionic hafnocene thiopurine complexes

Ionic chelates of hafnocene, with 6-mercaptopurine (HL¹) (A) and 6-thioguanine (HL²) (B) of the type [( ⁵-C₅H₅)₂HfL¹]⁺X^– (C) and [( ⁵-C₅H₅)₂HfL²]⁺X^– (D) (X = CuCl₃, ZnCl₃, CdCl₃, HgCl₃, PhNHNHCS₂) have been prepared and characterized by conductivity measurements and by i.r., electronic, ¹H-n.m.r. and ¹³C-n.m.r. spectra. Fluorescence studies of the complexes containing Hg in the anionic moiety, and relevant photochemical parameters, have been elucidated. Thermodynamic parameters have been calculated using thermogravimetric (t.g.) and differential thermal analytical (d.t.a.) curves and their variations have been correlated with some structural parameters of the complexes. The ligands, as well as their hafnium(IV) complexes, exhibit appreciable antibacterial and antifungal activity against E. coli, S. typhi, P. aeruginosa, Z. mobilis bacterial strains and versus A. awamori, A. niger fungal strains, respectively.