Poly(4-vinylphenol) (PVPh) was used as thermoplastic
modifier of epoxy resins. Binary epoxy/PVPh mixtures with high thermoplastic
content rise high glass transition temperatures (Tg)
after heating, due to the epoxy-phenol reaction. Blends with low PVPh percentages
reach high Tg if
2-methylimidazole is added, which catalyses epoxy homopolymerisation and epoxy-phenol
reaction. The cured blends do not present phase separation although the network
structure depends on the epoxy/phenol ratio. At low PVPh percentage the main
crosslinking reaction is epoxy-epoxy but, when the thermoplastic content increases,
the epoxy-phenol reaction prevails, causing an important Tg
increase and becoming less brittle.
Authors:S. Materazzi, S. Vecchio, L. W. Wo, and Curtis S. De Angelis
Manganese(II) coordination compounds with nitrogen donor ligands like substituted imidazoles have been thoroughly investigated during the past years. These compounds can be good models to simulate several
Authors:V. Udayakumar, S. Alexander, V. Gayathri, Shivakumaraiah, and B. Viswanathan
have reported the synthesis, characterization of polymer-supported palladium-imidazole complex catalyst and its use towards the hydrogenation of benzylideneaniline and a few of its para substituted derivatives at ambient conditions [ 11 ]. The catalytic
Authors:A. D. Katnani, K. I. Papathomas, D. P. Drolet, and A. J. Lees
Two Pd-imidazole complexes have been synthesized following the reaction of PdCl2 and imidazole at 1∶2 and 1∶4 metal∶ ligand ratios. Elemental and thermogravimetric analytical data obtained from these compounds illustrate that they have the formulae Pd(IMDAH)2Cl2 · 4H2O and Pd(IMDAH)3Cl2 (IMDAH = imidazole), respectively. The mechanism of thermal decomposition for these complexes in air involves initial dissociation of H2O and IMDAH ligands in the 120–340 °C range, subsequent dissociation of the chloride atoms to form PdO in the 530–570 °C range, and finally formation of Pd metal at 820–840 °C.
Authors:M. C. Navarro Ranninger, M. Gayoso Andrade, and M. A. Alario Franco
We describe in this paper the thermal decomposition in air of several complexes of palladium(II) chloride with imidazole and N-methylimidazole. Although the final process of the decomposition gives (PdCl2)n which then decomposes to pa ladium which oxidizes to PdO, there are interesting differences in the initial decomposition path. The reasons for these differences appear to be related to the trans-effect and to the presence in the imidazole complexes of hydrogen bonds which break down at temperatures of around 220‡.
The thermal decomposition in air of several complexes of chromium(III) with imidazole,N-methylimidazole and 2-methylimidazole has been studied with the aid of differential thermal analysis (DTA), thermogravimetry (TG) and derivative thermogravimetry (DTG) in the temperature range 25–600°C. Although the final process of the decomposition gives Cr2O3, there are interesting differences in the complete process of decomposition. The reasons for these differences appear to be related to the trans-effect and to the presence in the imidazole complexes of hydrogen bonds. Enthalpies of the several decomposition reactions have been determined by differential thermal analysis.
Authors:I. Labádi, Zs. Czibulya, R. Tudose, and O. Costisor
Parent and mixed ligand complexes of cobalt(II) and copper(II) ions with N,N'-bis- (4-antipyrylmethyl)piperazine or N,N'-tetra(4-antipyryl-methyl)-1,2-diaminoethane
or/and imidazole as ligand and ClO4- or SCN- as counterion were synthesised and their thermal behaviour was investigated.
The reaction products of Cu(II) 2-chlorobenzoate and the imidazole (1), and of Cu(II) 2,6-dichlorobenzoate and the imidazole
(2) formulated as CuL’2⋅2imd⋅2H2O and CuL”2⋅2imd⋅2H2O (L’=C7H4ClO2−, L”=C7H3Cl2O2−, imd=imidazole), were prepared and characterized by means of spectroscopic measurements and thermochemical properties. The blue
(1) and green (2) complexes were obtained as solids with a 1:2:2 molar ratio of metal to carboxylate ligand to imidazole.
When heated at a heating rate of 10 K min−1 the hydrated complexes, (1) and (2), lose some of the crystallization water molecules and then decompose to gaseous products.
The thermal decomposition of some Ni(II)-carboxylate-imidazole complexes in a nitrogen atmosphere was studied non-isothermally.
From the non-isothermal thermoanalytical data, it was found that these complexes decompose through a stepwise release of imidazole
molecules and/or CO ones forming unstable intermediates which produce metal oxide or the metal as a final decomposition product.
TG in conjunction with DTG were used to evaluate the kinetic and thermodynamic parameters of the decomposition reaction. The
kinetic studies were performed employing a computer-oriented kinetic analysis of each set of W-T data obtained under constant heating rate. The diffusion processes are the decisive mechanisms for the decomposition. The
values of ΔE, A, ΔH, ΔS and ΔG for activation were calculated for the complexes and correlated to variation in their structure.
Solid-state complexes with the formulae CuLxX2·nH2O, wereL=2-methyl-, 5-methyl-, or 7-methylpyrido[2,3-d]imidazole,X=NO3− or Cl−,x=2 or 3, andn=1 or 2, were subjected to thermogravimetric analyses. The kinetic parameters were calculated according to the Coats-Redfern method. Reactions paths are proposed and their agreement with the data obtained from TG curves is checked.