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Journal of Thermal Analysis and Calorimetry
Authors: V. Šutinská, M. Pajtášová, D. Ondrušová, S. Ľalíková, A. Ferjancová, J. Paliesková and S. C. Mojumdar

Introduction Polyether polyols together with polyisocyanates are essential components in the manufacture of polyurethanes. The commercial production of polyether polyols is conducted by ring opening polymerization of epoxides

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Abstract  

The formation of polynuclear thorium hydroxide complexes in acidic aqueous solutions is observed by electrospray mass spectrometry. Size, number of hydroxide ligands and charge of all complexes in solution are identified independently. By repeated measurements over a time span of up to 418 days the stability of the polymers is observed. At concentrations above [Th(IV)]tot = 10 mM pentamers and dimers are the dominant stable species. In contrast, the fractions of pentamers initially present at [Th(IV)]tot = 0.2 mM decrease within less than 4 weeks, correlated with the formation of nm-sized colloids observed by LIBD indicating an Ostwald-ripening like process.

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Journal of Thermal Analysis and Calorimetry
Authors: I. Popovic, L. Katsikas, A. Prazic, S. Schrötter, H. Weller and J. Velickovic

Abstract  

The application of derivativ thermogravimetry (DTG) to investigate polymerisation mechanisms is illustrated using the radical polymerisation of di-n-alkyl itaconates as well as the photoinitiated polymerisation of methyl methacrylate by colloidal CdS. The thermal properties of the resulting polymers are described. The advantages and disadvantages of DTG are discussed.

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cross-linked three-dimensional network polymers [ 3 ]. The main monomers/oligomers used in the resinous matrix phase are bisphenylglycidyl dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA). The

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Evaluation of different light-curing lamps

Halogen versus new-diode lamp

Journal of Thermal Analysis and Calorimetry
Authors: Maurizio Ferrante, Paolo Dottore, Morena Petrini, Paolo Trentini and Giuseppe Spoto

reaction [ 1 ]. When the composite resins are irradiated, the radicals generated attack the double bonds of the monomers, creating cross-linked three-dimensional network polymers [ 2 ]. These materials are composed basically by two phases: a

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production of compounds [ 3 ]. An often found criticism on flow reactions, especially in the realm of polymer chemistry where highly viscous or heterogeneous reaction mixtures are very common, is that reactors must be optimized for each reactor and that flask

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Abstract  

In this paper the polymerisation of linseed oil is studied in order to prove the catalytic action of some inorganic pigments. The results show that the calorimetric technique is able to monitor the polymerisation process in the temperature range between 130 and220C; reproducible values for isothermal analysis are obtained between 130 and 150C;finally the results are quantitative and can be justified by kinetic equations.

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Abstract  

Conventionally polymerisation of pyrrole is carried out either by chemical or electrochemical oxidation. In the present study polymerisation of pyrrole was carried out in a novel way in order to investigate the kinetics of the reactions involved. Carbonate radical (CO3 ) generated either radiolytically or photolytically from a sodium carbonate solution, was employed as the oxidant for the polymerisation reaction Flash photolysis and steady state ψ-radiolysis of pyrrole solution containing sodium carbonate was used for generating different intermediate and stable polymeric species. The kinetics of the formation and decay of different intermediate species were studied using UV-VIS spectrophotometry and the disappearances of the monomer was ascertained using HPLC. After analysing the species and steps involved a plausible mechanism for the polymerisation of pyrrole is suggested.

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Abstract  

Radiation initiated polymerisation of N,N-dimethyl acrylamide was investigated in an aqueous medium. The polymerisation followed first order kinetics at all the concentration of monomers used. The rate constant is 0.024 h–1 at a dose rate of 270 rad/min, for 0.025 mol·dm–3.

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typical polymer LED (Light emitting diode), shown schematically in Fig. 1 , is made by sandwiching a layer of light emitting LEP polymer between a pair of electrodes across a pixel having characteristic dimensions of ~50 μ and typical polymer depths of

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