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Thermal Studies (thermal + studies)
Selected AbstractsStructural and Thermal Studies on Na2Th(MoO4)3, Na2Pu(MoO4)3, Na4Th(MoO4)4 and Na4Pu(MoO4)4.CHEMINFORM, Issue 31 2006N. D. Dahale Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Functional modification of poly(vinyl alcohol) through phosphorus containing nitrogen heterocyclic moietiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008S. Karpagam Abstract Functional modification of poly(vinyl alcohol) (PVA) with phosphorus containing nitrogen heterocyclic has been believed to have extensive thermal and biological applications in the area of polymers. Efforts have been taken for the synthesis of phosphorus-containing N -heterocyclic (5,6 member and fused ring) based PVA. The synthesized compounds were characterized using UV, FTIR, and NMR spectral studies. Thermal studies (DSC-TGA) scans display phosphorus-containing five membered and fused heterocyclic-based PVA has less thermal stability than six-membered compounds. Modified polymers infer to have excellent bacterial response against micro-organisms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Thermomechanical studies of aluminum nitride filled shape memory polymer compositesPOLYMER COMPOSITES, Issue 3 2007Muhammad Yasar Razzaq High thermal conductivity polyurethane shape memory polymer (SMP) composites filled with aluminum nitride (AlN) were fabricated, and their thermal and thermomechanical properties were studied. The purpose of this microstructure is to improve the thermal properties of the SMPs at low filler content. Morphology of AlN filler in polyurethane SMP matrix and the resulting thermal conductivity was also investigated. Thermal studies have shown that AlN is an effective filler for reinforcement of the polyurethane SMP and that it does not deteriorate the stable physical crosslink structure of the polyurethane, which is necessary to store the elastic energy in the service process of the shape memory material. The thermal conductivities of these SMP composites in relation to filler concentration and temperature were investigated, and it was found that the thermal conductivity can increase up to 50 times in comparison with that of the pure SMP. Furthermore, differential scanning calorimetry tests have shown a significant decrease in the glass transition temperature of the switching segment. Dynamic mechanical studies have shown that the storage modulus of the composites increase with higher AlN content in both glassy and rubbery state. Damping peak decreases and also the curve of damping becomes broader with increasing filler content. Strain fixity rate which expresses the ability of the specimens to fix their strain has been improved slightly in the presence of AlN filler but the final recovery rate of the shape memory measurement has decreased evidently. POLYM. COMPOS., 28:287,293, 2007. © 2007 Society of Plastics Engineers [source] Studies on thermal and morphological properties of 1,1-bis(3-methyl-4-cyanatophenyl)cyclohexane-epoxy-bismaleimide matricesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2003K. Dinakaran Abstract A new cyanate ester monomer, 1,1-bis(3-methyl-4-cyanatophenyl)cyclohexane has been synthesized and characterized. Epoxy modified with 4, 8 and 12% (by weight) of cyanate ester were made using epoxy resin and 1,1-bis(3-methyl-4-cyanatophenyl)cyclohexane and cured by using diaminodiphenylmethane. The cyanate ester modified epoxy matrix systems were further modified with 4, 8 and 12% (by weight) of bismaleimide (N,N,-bismaleimido-4,4,-diphenylmethane). The formation of oxazolidinone and isocyanurate during cure reaction of epoxy and cyanate ester blend was confirmed by IR spectral studies. Bismaleimide-cyanate ester-epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and heat deflection temperature (HDT) analysis. Thermal studies indicate that the introduction of cyanate ester into epoxy resin improves the thermal degradation studies at the expense of glass transition temperature. Whereas the incorporation of bismaleimide into epoxy resin enhances the thermal properties according to its percentage content. However, the introduction of both cyanate ester and bismaleimide influences the thermal properties according to their percentage content. DSC thermogram of cyanate ester modified epoxy and bismaleimide modified epoxy show unimodel reaction exotherms. The thermal degradation temperature and heat distortion temperature of the cured bismaleimide modified epoxy and cyanate ester-epoxy systems increased with increasing bismaleimide content. The morphology of the bismaleimide modified epoxy and cyanate ester-epoxy systems were also studied by scanning electron microscopy. Copyright © 2003 John Wiley & Sons, Ltd. [source] Studies on the synthesis and thermal properties of alkoxysilane-terminated organosilicone dendrimersAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2010Kanak Saxena Abstract Silicone core dendrimers bearing terminal dialkoxy and trialkoxy silane groups were prepared in a three-step synthesis. Initially, the SiH terminated multifunctional silicone dendrimer, i.e. tetrakis(dimethylsiloxy)silane, was prepared by the reaction of tetraethoxysilane and dimethylethoxysilane. Tetrakis(dimethylsiloxy)silane on reaction with allylglycidylether in the presence of Speier's catalyst under pressure (100 psi) yielded epoxy-terminated dendrimer in very high yield (95%). The epoxy-terminated dendrimer was reacted with aminopropylalkoxysilanes to yield the next-generation dendrimer bearing dialkoxy and trialkoxy silane groups. The dendrimers were characterized by the usual physico-chemical techniques, i.e. elemental analysis, FT-IR, 1H, 13C and 29Si NMR. Thermal studies (Thermogravimetric analysis and Thermomechanical analysis) of the alkoxy terminated dendrimers and its cured products were also carried out. Copyright © 2010 John Wiley & Sons, Ltd. [source] Synthesis, structural characterization, biological activity and thermal study of tri- and diorganotin(IV) complexes of Schiff base derived from 2-aminomethylbenzimidazoleAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2009Mala Nath Abstract This report deals with the synthesis and structural features of tri- and diorganotin(IV) complexes of the general formulae, RnSn(L)m [n = 3, m = 1, R = Me, n -Bu and Ph; n = 2, m = 2, R = Me, n -Bu, n -Oct and Ph; HL = Schiff base derived from the condensation of 2-aminomethylbenzimidazole (ambmz) and salicylaldehyde (abbreviated as HL or Hsal-ambmz)]. The newly synthesized complexes were characterized by elemental analysis, molar conductance, electronic, infrared, far-infrared, 1H NMR, 13C NMR, 119Sn NMR and 119Sn Mössbauer spectral studies. Thermal studies of all of the synthesized complexes were also carried out using thermogravimetry,differential thermal analysis-derivative thermogravimetric (TG-DTA-DTG) techniques. The residues thus obtained were characterized by infrared and powder X-ray diffraction analysis. The bioassay results of anti-inflammatory activity (using the carrageenan-induced paw edema bioassay in rats) and acute toxicity (LD50) of the synthesized derivatives indicated that diorganotin(IV) derivatives (19.75,22.23% inhibition) show better activity as compared with triorganotin(IV) derivatives (10.32,17.86% inhibition). Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis, structural and thermal studies of tetrathioureacopper(I) chloride crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2005M. Dhandapani Abstract Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X-ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 Å, c = 13.8074 Å, V = 2482.29 Å3, , = , = , = 90°. Space group and the number of molecules per unit cell (Z) are found to be P41212 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 °C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 °C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 °C. Thermal anomalies observed in the low temperature DSC at ,163.3, ,152.0, ,141.5, ,108.3, 1.0 and 12.1 °C in the heating run and ,157.1 and ,153.9 °C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at ,146.2 °C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, characterization, and kinetic of thermal degradation of oligo-2-[(4-bromophenylimino)methyl]phenol and oligomer-metal complexesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009smet Kaya Abstract Oligo-2-[(4-bromophenylimino)methyl]phenol (OBPIMP) was synthesized from the oxidative polycondensation reaction of 2-[(4-bromophenylimino)methyl]phenol (BPIMP) with air and NaOCl oxidants in an aqueous alkaline medium between 50 and 90°C. The yield of OBPIMP was found to be 67 and 88% for air and NaOCl oxidants, respectively. Their structures were confirmed by elemental and spectral such as IR, ultraviolet,visible spectrophotometer (UV,vis), 1H-NMR, and 13C-NMR analyses. The characterization was made by TG-DTA, size exclusion chromatography, and solubility tests. The resulting complexes were characterized by electronic and IR spectral measurements, elemental analysis, AAS, and thermal studies. According to TG analyses, the weight losses of OBPIMP, and oligomer-metal complexes with Co+2, Ni+2, and Cu+2 ions were found to be 93.04%, 59.80%, 74.23%, and 59.30%, respectively, at 1000°C. Kinetic and thermodynamic parameters of these compounds investigated by Coats-Redfern, MacCallum-Tanner, and van Krevelen methods. The values of the apparent activation energies of thermal decomposition (Ea), the reaction order (n), preexponential factor (A), the entropy change (,S*), enthalpy change (,H*), and free energy change (,G*) obtained by earlier-mentioned methods were all good in agreement with each other. It was found that the thermal stabilities of the complexes follow the order Cu(II) > Co(II) > Ni(II). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Order-disorder enantiotropy, monotropy, and isostructurality in a tetroxoprim-sulfametrole 1:1 molecular complex: Crystallographic and thermal studiesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2003Mino R. Caira Abstract Two enantiotropic polymorphs of a tetroxoprim (TXP)-sulfametrole (SMTR) 1:1 molecular complex monohydrate and two isostructural TXP-SMTR 1:1 molecular complex solvates with methanol and ethanol were grown and studied by X-ray diffraction and thermal methods (thermogravimetric analysis and differential scanning calorimetry). Interconversion of the polymorphic hydrates is essentially an order/disorder transition involving a substituent on the TXP molecule. These hydrated phases may be described as "nearly isostructural" with the methanol and ethanol solvates. Thermal data for decomposition of the solvates were rationalized on the basis of the location and topologies of solvent crystallographic sites. Solid-state properties of two monotropic polymorphs of the unsolvated TXP-SMTR 1:1 molecular complex were also investigated and the theoretical and experimental phase diagrams of the individual components were assessed. The existence of polymorphic and pseudopolymorphic forms is determined by conformational flexibility of the TXP-SMTR bimolecular complex components, a tendency for molecular disorder in TXP, the ability of the drug complex to form intricate, highly stabilized hydrogen-bonded frameworks, and the competition between nonspecific van der Waals and specific hydrogen bond interactions. © 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:2164,2176, 2003 [source] Modification of recycled high-density polyethylene by low-density and linear-low-density polyethylenes,POLYMER ENGINEERING & SCIENCE, Issue 1 2003N. Kukaleva The present study investigated mixed polyolefin compositions with the major component being a post-consumer, milk bottle grade high-density polyethylene (HDPE) for use in large-scale injection moldings. Both rheological and mechanical properties of the developed blends are benchmarked against those shown by a currently used HDPE injection molding grade, in order to find a potential composition for its replacement. Possibility of such replacement via modification of recycled high-density polyethylene (reHDPE) by low-density polyethylene (LDPE) and linear-low-density polyethylene (LLDPE) is discussed. Overall, mechanical and rheological data showed that LDPE is a better modifier for reHDPE than LLDPE. Mechanical properties of reHDPE/LLDPE blends were lower than additive, thus demonstrating the lack of compatibility between the blend components in the solid state. Mechanical properties of reHDPE/LDPE blends were either equal to or higher than calculated from linear additivity. Capillary rheological measurements showed that values of apparent viscosity for LLDPE blends were very similar to those of the more viscous parent in the blend, whereas apparent viscosities of reHDPE/LDPE blends depended neither on concentration nor on type (viscosity) of LDPE. Further rheological and thermal studies on reHDPE/LDPE blends indicated that the blend constituents were partially miscible in the melt and cocrystallized in the solid state. [source] Spectroscopic and thermal studies of poly[(N -vinylimidazole)- co -(maleic acid)] hydrogel and its quaternized formPOLYMER INTERNATIONAL, Issue 4 2008Nursel Pekel Abstract BACKGROUND: In this study, poly[(N -vinylimidazole)- co -(maleic acid)] (poly(VIm/MA)) hydrogels were prepared by ,-irradiation of ternary mixtures of N -vinylimidazole,maleic acid,water using a 60Co ,-source. Spectroscopic and thermal analyses of these hydrogels as a function of protonation showed that the results are consistent with the existence of an H-bridged complex when the imidazole rings are partially protonated. Finally, the efficiency and binding trends of Cu2+, Co2+, Cd2+ and Pb2+ ions with both protonated and unprotonated poly(VIm/MA) hydrogels were determined. RESULTS: Gelation of 90% was reached at around 180 kGy dose at the end of irradiation. The poly(VIm/MA) hydrogels synthesized were further protonated in HCl solutions with different concentrations. Hydrogels originally showed 450% volumetric swelling; this ratio reached 1900% after protonation at pH = 5.0. Fourier transform infrared spectral changes in the +NH stretching region (3200,3600 and 1173 cm,1) and the ring mode deformation at 915 cm,1 are consistent with the formation of an H-bridged complex between the protonated and unprotonated imidazole rings upon partial protonation. Similar changes were obtained from NMR spectra of both the protonated and unprotonated forms of the hydrogels. CONCLUSION: Protonated and unprotonated hydrogels have been used in heavy metal ion adsorption studies for environmental purposes. Adsorption decreased with decreasing pH value due to the protonation of the VIm ring. The adsorption of Me2+ ions decreased in the order Cu2+ > Co2+ > Cd2+ > Pb2+, which is related to the complexation stability as well as the ionic radius of the metal ions. These results show that P(VIm/MA) hydrogels can be used efficiently to remove heavy metal ions from aqueous solutions. However, the protonated form is a bad choice for heavy metal ion adsorption due to electrostatic repulsion forces; it can nevertheless be assumed to be a good choice for anion adsorption from environmental waste water systems. Copyright © 2007 Society of Chemical Industry [source] In-vitro antimicrobial, thermal and spectral studies of mixed ligand Cu(II) heterochelates of clioquinol and coumarin derivativesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010G. J. Kharadi Abstract The mixed-ligand heterochelates of Cu(II) with 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol) and various uninegative bidentate ligands were prepared. The structure of mixed-ligand heterochelates was investigated using spectral, physicochemical, elemental analysis and thermal studies. The FAB-mass spectrum of [Cu(A2)(CQ)(H2O)2].2H2O has been carried out. Magnetic moment and reflectance spectral studies reveal that an octahedral geometry has been assigned to all the prepared heterochelates. The kinetic parameters such as order of reaction (n), the energy of activation (Ea), the pre-exponential factor (A), the activation entropy (,S#), the activation enthalpy (,H#) and the free energy of activation (,G#) have been reported. The ligands, metal salts, heterochelates, control and standard drug were tested for their in-vitro antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Bacillus substilis. The metal complexes exhibit good activity against bacterial strains compared with parental compounds, and moderate compared with the standard drug (clioquinol). Copyright © 2010 John Wiley & Sons, Ltd. [source] Novel drug-based Fe(III) heterochelates: synthetic, spectroscopic, thermal and in-vitro antibacterial significanceAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2010D.H. Jani Abstract A series of novel heterochelates of the type [Fe(An)(L)(H2O)2],mH2O [where H2An = 4,4,-(arylmethylene)bis(3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-ol); aryl = 4-nitrophenyl, m = 1 (H2A1); 4-chlorophenyl, m = 2 (H2A2); phenyl, m = 2 (H2A3); 4-hydroxyphenyl, m = 2 (H2A4); 4-methoxyphenyl, m = 2 (H2A5); 4-hydroxy-3-methoxyphenyl, m = 1.5 (H2A6); 2-nitrophenyl, m = 1.5 (H2A7); 3-nitrophenyl, m = 0.5 (H2A8); p -tolyl, m = 1 (H2A9) and HL = 1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid] were investigated. They were characterized by elemental analysis (FT-IR, 1H- & 13C-NMR, and electronic) spectra, magnetic measurements and thermal studies. The FAB-mass spectrum of [Fe(A3)(L)(H2O)2],2H2O was determined. Magnetic moment and reflectance spectral studies revealed that an octahedral geometry could be assigned to all the prepared heterochelates. Ligands (H2An) and their heterochelates were screened for their in-vitro antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Serratia marcescens bacterial strains. The kinetic parameters such as order of reaction (n), the energy of activation (Ea), the pre-exponential factor (A), the activation entropy (,S#), the activation enthalpy (,H#) and the free energy of activation (,G#) are reported. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||