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91.
Jobi Kodiyan Varghese Dong Sik Park Jong Yeob Jeon Bun Yeoul Lee 《Journal of polymer science. Part A, Polymer chemistry》2013,51(22):4811-4818
Simple mixing of H3Co(CN)6 and ZnCl2 in methanol resulted in precipitates of [ZnCl]+2[HCo(CN)6]2?, constituting a new type of double metal cyanide (DMC) catalyst exhibiting a high performance in carbon dioxide (CO2)/propylene oxide (PO) copolymerization. High‐molecular‐weight poly(propylene carbonate‐co‐propylene oxide)s [poly(PC‐co‐PO)s] (Mn~40,000) were consistently obtained with high carbonate fractions (~60 mol %) and a high selectivity (>95%) with the new type of DMC catalyst. Conventional preparation of the DMC catalyst using K3Co(CN)6 and ZnCl2 required removing KCl through thorough washing and resulted in lower carbonate fractions (10–40 mol %), which depended on the washing conditions. Feeding hydrophobic diols such as 1,10‐decanediol as chain transfer agent preserved the high carbonate fraction (~60%) and enabled precise control of the molecular weight, including preparation of a low‐molecular‐weight poly(PC‐co‐PO)‐diol (Mn ~2000), which was a flowing viscous liquid with a low Tg (?30 °C) suitable for polyurethane applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4811–4818 相似文献
92.
Seema Jaggi Cini Varghese Eldho Varghese V.K. Sharma 《Statistics & probability letters》2010,80(7-8):706-710
Generalized incomplete Trojan-type designs are defined to be row–column designs in which each cell, corresponding to the intersection of row and column, contains more than one treatment and the rows are incomplete. A method of constructing generalized incomplete Trojan-type design has been developed and some properties of this class of designs are discussed. 相似文献
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The effect of phase‐pure cristobalite (a high temperature crystalline polymorph of silica) on the adhesive characteristics of hydroxyl terminated polydimethylsiloxane (PDMS) was studied. The potential advantages of PDMS/cristobalite composite system as an adhesive for aerospace applications are also discussed. A PDMS/cristobalite composite adhesive system containing different filler contents (0–46 volume percentage, vol%) was prepared. The filler material, phase‐pure cristobalite, was synthesized by the pyrolysis of fused silica at 1400°C. The mechanical, rheological, and thermal characteristics of the composites were studied. A high yield stress (0.151 Pa), shear‐thinning index (1.051), and fast recovery rate were observed for ~34 vol% cristobalite loading, which indicate that PDMS retains its excellent adhesive and flow characteristics even at high filler loading with enhanced mechanical characteristics. Thermal analysis shows the onset of degradation of PDMS shifts to higher temperatures, 372–438°C and 317–417°C in nitrogen and air atmosphere respectively, which shows excellent thermal stability. The residual component yields after thermal degradation of PDMS/cristobalite composite system in nitrogen and air atmosphere show different degradation mechanisms. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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C.J. Antony M. Junaid Bushiri Hema Tresa Varghese C. Yohannan Panicker Michel Fleck 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,73(5):942-945
Raman and FTIR spectra of guanidinium zinc sulphate [C(NH2)3]2Zn(SO4)2 are recorded and the spectral bands assignment is carried out in terms of the fundamental modes of vibration of the guanidinium cations and sulphate anions. The analysis of the spectrum reveals distorted SO42− tetrahedra with distinct S–O bonds. The distortion of the sulphate tetrahedra is attributed to Zn–O–S–O–Zn bridging in the structure as well as hydrogen bonding. The CN3 group is planar which is expressed in the twofold symmetry along the C–N (1) vector. Spectral studies also reveal the presence of hydrogen bonds in the sample. The vibrational frequencies of [C(NH2)3]2 and HC(NH2)3 are computed using Gaussian 03 with HF/6-31G* as basis set. 相似文献
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Varghese B Cheong FC Sindhu S Yu T Lim CT Valiyaveettil S Sow CH 《Langmuir : the ACS journal of surfaces and colloids》2006,22(19):8248-8252
We report a simple and effective approach to organize micron- and submicron-sized particles in a size selective manner. This approach utilizes the template assisted directed self-assembly technique. A topographically patterned photoresist surface is fabricated and used to create an ordered array of colloidal particles from their aqueous suspensions. Assembly of particles on this template is then achieved by using a conventional spin coating technique. Feasibility of this technique to form a large area of patterned particle assemblies has been investigated. To arrange the particles on the template, the physical confinement offered by the surface topography must overcome a joint effect of centrifugal force and the hydrophobic nature of the photoresist surface. This concept has been extended to the size selective sorting of colloidal particles. The capability of this technique for sorting and organizing colloidal particles of a particular diameter from a mixture of microspheres is demonstrated. 相似文献
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