Search Results
Abstract
Three Mn(II), Co(II), and Cu(II) new transition metal complexes of the fluorescence dye: 2-(2′-hydroxy-5′-phenyl)-5-aminobenzotriazole/PBT derived from o-aminophenol and m-phenylenediamine have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility and molar conductivity, as well as from mass, IR, UV–Vis spectral studies. From the analytical, spectroscopic, and thermal data, the stoichiometry of the mentioned complexes was found to be 1:2 (metal:ligand). The molar conductance data revealed that all the metal chelates are non-electrolytes and the chloride ions exist inside the coordination sphere. The thermal stabilities of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these three complexes are investigated. The kinetic parameters such as the energy of activation (E*), pre-exponential factor (A), activation entropy (ΔS*), activation enthalpy (ΔH*), and free energy of activation (ΔG*) have been reported. Photostability of phenyl benzotriazole as fluorescence dye and their metal complexes doped in polymethyl methacrylate/PMMA were exposed to UV–Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period.
Non-isothermal thermogravimetry of polymer
I. General model involving formal termination of active centres
A Model of polymer decomposition is proposed which formally involves the termination of active centres. It yields reasonable activation energies for the decompositions of polypropylene, polyethylene, polystyrene and polymethyl methacrylate investigated by non-isothermal thermogravimetry. In the value of a formal reaction orders the model reflects the reaction conditions, such as initial sample weight, atmosphere, ventilation conditions, sample holder nature and shape, etc.
Abstract
The phase behaviour of thermoplastic polymer-dispersed liquid crystal system is studied with particular emphasis on the various transitions that occur within the system. The extent of plasticization of the polymer(polymethyl methacrylate) by the low molecular weight liquid crystal(E7) along with the several transitions of theLC(Liquid Crystal) are determined by modulated DSC. Optical microscopy was used to construct the temperature versus composition phase diagram. Our study indicates the existence of a limiting temperature of 40°C around which the PMMA matrix turns glassy irrespective of the initial composition within the phase separated region, suggesting the intersection of the glass transition curve with the coexistence curve. A slight depression of theN-I(Nematic to Isotropic) transition of theLC is observed with increasing composition of PMMA whereas theS-M(Smectic to Nematic) transition and theT g (Glass transition temperature) of theLC remain unaffected. The one phase mixture remains isotropic until phase separation at a lower temperature where theLC rich domains become nematic. The growth ofLC rich domains is studied as a function of temperature and time.
139 193 198 Vallittu, P. K., Ekstrand, K. (1999) In vitro cytotoxicity of fibre-polymethyl methacrylate composite used in dentures. J. Oral
diameter. After the procedures, the distal third of each tibia was cemented into a steel cylinder using polymethyl methacrylate (PMMA; Demotec, Demotec 90). The proximal third of each tibia was fixed into an aluminium bowl using epoxy resin (Novia, WWA
HI , Chiang YH : Percutaneous transpedicular vertebroplasty with polymethyl methacrylate for pathological fracture of the spine . J Clin Neurosci 16
-isothermal thermogravimetry . J Food Nutr Res . 2006 ; 45 : 166 – 170 . 14. Šimon , P , Zhong , W , Bakoš , D , Hynek , D . Thermooxidative stability of polymethyl methacrylate containing nanoparticles
. Int J Mol Sci 2022 ; 23 ( 15 ): 8308 . 9. Maluf CV , Peroni LV , Menezes LR , Coutinho W , Lourenço EJV , Telles DM . Evaluation of the physical and antifungal effects of chlorhexidine diacetate incorporated into polymethyl
. Shibaev , LA , Antonova , TA , Vinogradova , LV , Ginzburg , BM , Ginzburg , VG , Zgonnik , VN , Melenevskaya , EYu 1997 Mass-spectrometric investigation of the thermal stability of polymethyl methacrylate in the presence of C 60 fullerene
