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1.
P. Banu Ganga Radhakrishnan 《Journal of polymer science. Part A, Polymer chemistry》2004,42(2):341-350
The phase‐separation behavior of thermoplastic poly(ester‐imide) [P(E‐I)] multiblock copolymers, (A‐B)n, was investigated by a stepwise variation of the imide content. All the multiblock copolymers were synthesized by solution polycondensation with dimethylformamide as a solvent. P(E‐I)s were prepared with anhydride‐terminated polyester prepolymer and diisocyanates. Polyester prepolymers were prepared by the reaction of pyromellitic dianhydride and two different polyols [poly(tetramethylene oxide glycol) (PTMG) and polycaprolactone diol (PCL)]. Structural determination was done with Fourier transform infrared spectroscopy and Fourier transform NMR, and the molecular weight was determined by gel permeation chromatography. The effect of the imide content on the thermal properties of the synthesized P(E‐I)s was investigated by thermogravimetric analysis and differential scanning calorimetry. The polymers were also characterized for static and dynamic mechanical properties. Thermal analysis data indicated that the polymers based on PTMG were stable up to 330 °C in nitrogen atmosphere and exhibited phase‐separated morphology. Polymers based on PCL showed multistage decomposition, and the films derived from them were too fragile to be characterized for static and dynamic mechanical properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 341–350, 2004 相似文献
2.
Scaling analysis of the magnitude series (volatile series) has been proposed recently to identify possible non-linear/multifractal signatures in the given data [Y. Ashkenazy, et al. Phys. Rev. Lett. 86 (2001) 1900; Y. Ashkenazy, et al. Physica A 323 (2003) 19; T. Kalisky, Y. Ashkenazy, S. Havlin. Phys. Rev. E 72 (2005) 011913]. In this article, correlations of volatile series generated from stationary first-order linear feedback process with Gaussian and non-Gaussian innovations are investigated. While volatile correlations corresponding to Gaussian innovations exhibited uncorrelated behavior across all time scales, those of non-Gaussian innovations showed significant deviation from uncorrelated behavior even at large time scales. The results presented raise the intriguing question whether non-Gaussian innovations can be sufficient to realize long-range volatile correlations. 相似文献
3.
N. T. Madhu P. K. Radhakrishnan W. Linert 《Journal of Thermal Analysis and Calorimetry》2006,84(3):607-611
The
phenomenological, kinetic and mechanistic aspects of the nitrate, chloride,
bromide and iodide complexes of nickel(II) with1,2-(diimino-4’-antipyrinyl)ethane
(GA) have been studied by TG and DTG techniques. The kinetic parameters like
activation energy, pre-exponential factor and entropy of activation were computed.
The rate controlling process in all stages of decomposition is random nucleation
with one nucleus on each particle (Mampel model). 相似文献
4.
Bhaskar M Gnanamani A Ganeshjeevan RJ Chandrasekar R Sadulla S Radhakrishnan G 《Journal of chromatography. A》2003,1018(1):117-123
Extracellular fluid protein (ECFP) of Streptomyces species SS07 has been used to reduce water soluble azo dyes and the carcinogenic amines released have been compared with that from chemical reduction. The effect of temperature, pH and contact time on the recovery of amines using ECFP was studied. The ECFP releases carcinogenic amines at a pH of 9.2 and a temperature of 37 degrees C for a contact period of 24 h. The reduction products were analyzed with HPLC and their structures confirmed by LC-MS and GC-MS. It was observed that both the ECFP and chemical reduction methods released similar type of amine products. In the case of dye samples, compared to chemical reduction, 5-20% increase in the release of carcinogenic amines by ECFP was observed. The percentage of amine products released by chemical reduction was higher for leather garment samples compared to ECFP treatment. 相似文献
5.
The thermal behaviour of a series of solution-cast blends of polyvinyl chloride/epoxidised liquid natural rubber (ELNR) of different mole percentage of epoxidation has been examined using thermogravimetric analysis. Thermal degradation is found to occur through a two-step route in which the first step corresponds to the dehydrochlorination of PVC to form a polyene and the second step is attributed to the decomposition of the ELNR and the polyene. Introduction of 20 and 50 mol% of epoxy group into the liquid NR is found to enhance the thermal stability of PVC. Probable mechanisms of degradation have been suggested on the basis of the kinetic analysis of the degradation studies. It is found that the mechanism is influenced by the epoxy content of the blend system. Activation energy for the degradation and the entropy change have also been reported. 相似文献
6.
A new single-pot procedure for the synthesis of aryl alkynes is described. Palladium catalyzes the coupling reaction of diaryliodonium compounds with enynes and electron-deficient alkynes to give aryl alkynes in good yields. 相似文献
7.
La2O(CN2)2 was synthesized from a 1:1:2 molar reaction mixture of LaCl3, LaOCl, and Li2(CN2) at 650 °C. Well developed single crystals were grown from a LiCl‐KCl flux. The crystal structure was refined as monoclinic (space group C2/c, Z = 2, a = 13.530(2) Å, b = 6.250(1) Å, c = 6.1017(9) Å, β = 104.81(2)°) from single crystal X‐ray diffraction data. The La3+ and (CN2)2— ions in the crystal structure of La2O(CN2)2 can be compared to Fe3+ and S22— ions in the cubic pyrite structure, being arranged like in a distorted NaCl type structure with their centers of gravity. In addition, the O2— ions in La2O(CN2)2 are occupying 1/4 of the tetrahedral voids formed by the arrangement of metal ions. 相似文献
8.
9.
Jinesh M. Kuthanapillil A. Nijamudheen Nayana Joseph Praveen Prakash E. Suresh Ayan Datta K.V. Radhakrishnan 《Tetrahedron》2013
A detailed investigation on the effect of solvent polarity, temperature, and microwave irradiation on periselectivity in cycloaddition reactions of pentafulvenes with 3-oxidopyrylium betaine is described. The base catalyzed generation of 3-oxidopyrylium betaine in CHCl3 resulted in the exclusive formation of [6+3] adducts. With increase in solvent polarity and temperature, mixtures of [6+3] and [3+2] adducts were formed, where as under microwave irradiation, [3+2] adducts were formed exclusively. The experimental results have been rationalized on the basis of theoretical calculations. 相似文献
10.
Syntheses of 1b-d is described using 1-chloro-2-deoxy-3,5-di-p-toluoyl-D-erythro-pentosyl chloride. 相似文献