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  • Author or Editor: A. Pollicino x
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Abstract  

The polycondensation reactions between 4,4′-[sulphonyl bis(p-benzoyl)(p-phenyleneoxy)]dibenzoic acid (I) andp-phenylenediamine (II), 1,5-diaminonaphthalene (III), 4,4′-sulphonyldianiline (IV), 4,4′-diaminodiphenylsulphide (V) 4,4′-methylenedianiline (VI) and 4,4′-oxydianiline (VII) to form aromatic polyamides containing sulphone, ether and ketone linkages were attempted by a solid-solid interaction route. A stoichiometric 1∶1 molar ratio of solid reactants was dynamically heated directly in a TG/DSC apparatus, and simultaneous TG/FT-IR was performed to interpret the mechanism of reaction. The results suggest that the polycondensation is dependent on the diamine used. The formation of polyamide was successful when I interacted with II, III, VI and VII. The interaction with IV and V was in part successful because partial decarboxylation of the diacid, made unstable by the diamine, occurred before the condensation reaction.

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Abstract  

The degradation of a new thermoplastic poly(arylene)ether copolymer was carried out in both dynamic and isothermal heating conditions, under nitrogen flow and in a static air atmosphere. The measurements showed that the copolymer degraded through two stages in both investigated environments with the formation of a stable residue in N2 and complete mass loss in air. The apparent activation energy values associated with the degradation processes were evaluated. The obtained results suggested different degradation mechanisms between N2and air. Results were discussed and compared with those obtained for several polymers previously investigated.

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Abstract  

Styrene and montmorillonite organically modified with imidazolium surfactants (MMT) at various alkyl chain lengths (C12, C16 and C18) were used to prepare the corresponding PS/MMT/C12, PS/MMT/C16 and PS/MMT/C18 nanocomposites by in situ polymerization. XRD and TEM analyses evidenced the formation of both intercalated and exfoliated structures. The glass transition temperatures (T g) of nanocomposites, as well as that of neat PS, were obtained by DSC measurements. The thermal degradations were carried out in the scanning mode, in both inert and oxidative environments, and the initial temperatures of decomposition (T i) and the apparent activation energies of degradation (E a) were determined. Due to an oxidative degradation mechanism, the T i and E a values in air atmosphere were lower than those under nitrogen. The results indicated that nanocomposites are more thermally stable than polystyrene, and suggested an increasing degree of exfoliation as a function of alkyl chain length of surfactant, associated with enhancing thermal stability.

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Abstract  

Thermochemical properties of two kinds of composite material of synthetic zeolite ZSM5 in potassium form (K-ZSM5) with AgI have been studied. The composites have been prepared by treating the silver form of synthetic zeolite ZSM5 (Ag-ZSM5) with potassium iodide solution under different experimental conditions. One of the composites was additionally sintered at temperature 500C for 20 h. Both composites have been characterized by TG, DTG, DTA, EDS analysis, X-ray powder diffractometry and X-ray photoelectron spectroscopy. The methods of thermal analysis as well as X-ray powder diffractometry and XPS confirmed the differences between the two composites caused by sintering during the synthesis. The content of AgI in the surface layer was different. No changes of the zeolitic mineral dimensions are observed.

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