http://nopr.niscpr.res.in/handle/123456789/41758 Thu, 08 Oct 2026 14:20:42 GMT 2026-10-08T14:20:42Z http://nopr.niscpr.res.in/handle/123456789/41851 Title: Thermodynamic analysis of critical limits in Belousov-Zhabotinskii reaction system Authors: Rastogi, R P; Syal, V; Misra, G P Abstract: Stability of the Belousov-Zhabotinskii (B-Z) reaction system containing bromate, ceric ammonium sulphate, sulphuric acid and mixed organic substrates (oxalic acid + acetone) has been examined using the thermodynamic theory of Glansdorff and Prigogine at the two critical limits of [acetone] and also in the oscillatory domain. The sign of excess entropy production due to perturbation in [HBrO₂] has been estimated by taking into account the subset of reactions involving HBrO₂. Numerical estimates of sign of relative excess entropy production for different reactions have been made using the latest accepted values of the rate constants (Field and Forsterling) as well as values of Field and Boyd. The thermodynamic analysis suggests that the reaction system is stabilized either when (i) the contribution to the excess entropy production due to destruction of HBrO₂ by Br^- exceeds the negative contribution due to autocatalytic reaction step or when (ii) the contribution of disproportionation of HBrO₂ to the excess entropy production exceeds or becomes comparable to the negative contribution due to autocatalytic reaction step. Situation (i) corresponds to lower limit of [acetone] while (ii) corresponds to upper limit of [acetone]. Instability can occur when the negative contribution due to the autocatalytic reaction exceeds the sum of contributions of disproportionation of HBrO₂ and its destruction by Br^-. Page(s): 203-208 Fri, 01 Mar 1991 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/41851 1991-03-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/41850 Title: Dimensional response of engineering polymeric elastomers in the presence of halo-substituted benzenes Authors: Harogoppad, S B; Aminabhavi, T M Abstract: Dimensional response of several engineering polymers in the presence of halo-substituted benzenes has been studied by weight-gain and swelling measurements. The experimental data have been used to estimate the diffusion coefficients, kinetic rate constants, activation parameters and molar mass between crosslinks for all the polymer-solvent systems. Page(s): 209-214 Fri, 01 Mar 1991 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/41850 1991-03-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/41849 Title: Template copolymerization of methyl methacrylate and styrene on poly(methyl methacrylate) Authors: Awasthi, Sanjay K; Srivastava, A K Abstract: The radical copolymerization of methyl methacrylate and styrene using syn-poly(methyl methacrylate) (M͞_V = 98,890) as template in dimethylformamide (DMF), at 60° for 150 minutes results in an alternate copolymer, as evidenced from NMR spectroscopy. Yiscometric measurements have shown that complexation between template and oligomer of syn-PMMA is maximum at template/copolymer ratio of 1:1 and the time of complexation is about 9 min. The average molecular weight (M͞_V) of $ughter copolymer is not identical to that of template because of chain transfer reaction to template. The template effect and average molecular weight' (M͞_V) of daughter copolymer are direct functions of concentration as well as M͞_V of template. The energies of activation for template and blank polymerization are 46.0 and 64.0 kJ mol^-1 respectively. The system follows Mechanism II, as evidenced from effect of an analogue and dioxane. Page(s): 215-218 Fri, 01 Mar 1991 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/41849 1991-03-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/41848 Title: Studies on NO_X conversion over transition metal ion (TMI) dopeq alumina-boria system Authors: Bose, J M; Banerjee, D; Guha, D Abstract: Catalytic decomposition of NO_X has been studied using a fixed bed tubular flow reactor in the temperature range 573-773K, over six aluminium-borate catalysts (containing 2Al₂O_3.B₂O₃ as the major phase and 9Al₂O_3.2B₂O₃ as the minor phase) doped with different transition metals. The catalyst phases have been characterised by XRD, IR, ESR and ESCA studies on fresh and used catalyst samples. The results indicate structural stability of the catalyst phase over the experimental temperature range and oxidation of Co²⁺ to CO³⁺ accompanied by surface migration of CO³⁺ species. No valence change in the other transition metal ions and surface oxygen enrichment in, the used catalyst .is observed. Kinetic studies show a first order dependence, on NO_X partial pressure in the lower temperature: region, except in the case of the mixed doped catalyst. Breaks in the Arrhenius plots at about 673K are noted for all the catalysts. Page(s): 219-224 Fri, 01 Mar 1991 00:00:00 GMT http://nopr.niscpr.res.in/handle/123456789/41848 1991-03-01T00:00:00Z