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Journal of Thermal Analysis and Calorimetry
Authors:
B. Ravindran
,
G. Madhurambal
,
M. Mariappan
,
K. Ramamurthi
, and
S. C. Mojumdar

Abstract

Single crystals of mercury cinnamate were grown by slow evaporation of methanol solution at room temperature. The effect of mercury on the electronic structure of cinnamic acid was studied. The grown mercury cinnamate single crystals were characterized by UV, FTIR and TG-DTA. TG curve of mercury cinnamate exhibits higher thermal stability compared with cinnamic acid which was also confirmed by DTA curve. The spectroscopic studies give evidences of the distribution of the electronic charge in molecule, the delocalisation of π electrons and the reactivity of metal complexes. The Second harmonic generation efficiency is more pronounced in the presence of mercury dopant in the growth medium.

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Abstract

Single crystals of a new nonlinear optical material, bisthiourea-urea have been grown from aqueous solution by slow evaporation technique with a period of 4 weeks. The structure of the grown crystals was confirmed by X-ray diffraction (XRD). The presence of title compound in the crystal lattice has been qualitatively determined by FTIR analysis. The mechanical properties and thermal stability of the grown crystals were evaluated by Vickers microhardness test and TG and DTG, respectively.

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Abstract

The growth and characterization of a new non-linear organometallic crystal, potassium thiourea thiocyanide (PTT) is reported. The growth of single crystals was accomplished by the slow evaporation solution growth method. The grown crystals were characterized by XRD, TG–DTA, UV, and FTIR spectral analyses. PTT has good optical transmission in the entire visible region which is an essential requirement for a non-linear crystal. TG curve of PTT undergoes complete decomposition between 176 and 1,000 °C in three steps with corresponding three DTA peaks. The high thermal stability of organometallic crystals are due to strong bonding existing between the conjugation layers of thiourea molecule and the potassium ions.

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Journal of Thermal Analysis and Calorimetry
Authors:
G. Vasudevan
,
P. AnbuSrinivasan
,
G. Madhurambal
, and
S. C. Mojumdar

Abstract

Potassium Hydrogen Phthalate also known as Potassium Acid phthalate (KAP) has 14 natural growth faces with dominating (010) face. As the (010) face is more suitable for any surface morphological studies, a number of crystal growth studies have been made on this material in recent years. Here this semi organic crystal was grown by Slow Evaporation Solution Growth Technique. The effect of ammonium sulphate as dopant on the characteristic properties of KAP crystal was studied by thermal and spectral analysis.

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Abstract

The transient hot-wire method is considered the most accurate technique to measure the thermal conductivity of fluids. In this study, a transient hot wire instrument which employs 25.4-μm-diameter tantalum wire with an insulating tantalum pentoxide coating has been used. This hot-wire cell with a thin insulating layer is suitable for measurement of the thermal conductivity of electrically conducting and polar liquids. Measurements of the thermal conductivity of 50 wt% solution of PAA [poly (acrylic acid)] in water and PAA–Na in 50 wt% water are reported here. These measurements were obtained in the temperature range of 299–368 K at 1 atmospheric pressure. The measurement of thermal conductivity is estimated to be accurate within ±4%.

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Edible wheat gluten (WG) protein films

Preparation, thermal, mechanical and spectral properties

Journal of Thermal Analysis and Calorimetry
Authors:
S. C. Mojumdar
,
C. Moresoli
,
L. C. Simon
, and
R. L. Legge

Abstract

Commercial wheat gluten (WG) films, hard wheat gluten films and soft wheat gluten films, plasticized with glycerol have been cast from water–ethanol solutions. The effect of aging on various film properties has been investigated. The films were aged for about 6 months at 50% relative humidity and ~25 °C, and the mechanical (tensile strength and the percentage of elongation at break (E b)), thermal (TG and DSC) and Attenuated Total Reflectance (ATR)-FTIR spectral properties have been studied. Changes in the protein structure were determined by ATR-FTIR spectroscopy. Films from soft WG exhibited the highest E b (508%) and the highest TS (6.33 MPa). The TG analysis results show that the moisture content in all three kinds of WG protein films is about 5%. The absence of the glycerol phase transition in DSC curves implies that there is no separate phase containing glycerol in the WG protein-glycerol films with 40% glycerol.

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Abstract

Sorption of hazardous pyridine derivates by copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) has been investigated. Sorption of 2-chloropyridine (clpy) and 2-ethylpyridine (ethylpy) from liquid and gas phase by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN analysis, thermal (TG, DTG and DTA) analysis, FTIR spectroscopy, X-ray powder diffractometry and determination of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(clpy) x -ZSM5, Cu-(ethylpy) x -ZSM5, Cu-CT, Cu-(clpy) x -CT and Cu-(ethylpy) x -CT zeolitic products with different composition (x depends on the experimental conditions of sorption of pyridine derivates) clearly confirmed their different thermal properties and the sorption of pyridine derivates. The main part of the decomposition process of zeolitic samples containing pyridine derivates occurs at considerably higher temperatures than the boiling point of pyridine derivates proving strong bond and irreversibility of clpy- and/or ethylpy–zeolite interaction. FTIR spectra showed well-resolved bands for pyridine derivates in the Cu-(clpy) x -zeolite and Cu-(ethylpy) x -zeolite. Surface area and pore volumes of the samples Cu-clpy-ZSM5, Cu-ethylpy-ZSM5, Cu-clpy-CT and Cu-ethylpy-CT in comparison with Cu-ZSM5 and Cu-CT decreased due to the adsorption of pyridine derivates.

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Abstract  

The effect of dopant, Os(VIII) on the growth process, crystalline perfection and properties of potassium hydrogen phthalate (KHP) single crystals grown by a slow evaporation solution growth technique has been investigated. The XRD analysis of black-colored doped specimen reveals slight structural changes as a result of doping. The SEM images exhibit defect centers and crystal voids. The complex formation of KHP with Os(VIII) is evidenced by the considerable shift in λmax of the doped specimen and enhanced fluorescence intensity is observed by doping. Differential scanning calorimetry (DSC) and TG-DTA studies reveal the purity of the sample and no decomposition is observed up to the melting point. The high resolution X-ray diffraction (HRXRD) studies used to evaluate the crystalline perfection reveal some features on the capability of accommodating the dopant in the crystalline matrix. The diffraction curve (DC) patterns indicate that the high valence transition metal predominantly occupies the interstitial positions and the doping depresses the second harmonic generation (SHG) efficiency owing to the deterioration of crystalline perfection disturbing the charge transfer and nonlinearity.

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Journal of Thermal Analysis and Calorimetry
Authors:
V. Meenatchi
,
K. Muthu
,
M. Rajasekar
,
S. P. Meenakshisundaram
, and
S. C. Mojumdar

Abstract

Single crystals of o-hydroxybenzoic acid (o-HBA, salicylic acid) have been grown by slow evaporation solution growth technique. It crystallizes in monoclinic system with two molecular units in the cell (centrosymmetric space group P21/c). The lattice parameters are a = 4.8967(6) Å, b = 11.2204(14) Å, c = 11.3027(15) Å and β = 92.096(12)°. The modes of vibrations of different functional groups present were identified by FT-IR studies. Differential scanning calorimetry (DSC) study reveals the purity of the sample and no decomposition is observed up to the melting point. The crystals are further characterized using UV–Vis and powder XRD. Effect of solvents on the growth and morphology has been investigated. The crystalline cohesion is achieved by intra and intermolecular hydrogen bonds.

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Journal of Thermal Analysis and Calorimetry
Authors:
V. Šutinská
,
M. Pajtášová
,
D. Ondrušová
,
S. Ľalíková
,
A. Ferjancová
,
J. Paliesková
, and
S. C. Mojumdar

Abstract

A double metal cyano (DMC) catalyst is very effective for ring opening polymerization of propylene oxide (PO). The characteristics of the DMC complex were studied by Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). DMC complex generally result in a significant reduction of monols in the polyol production process. DMC catalyst is characterized by an approximately 1000 times higher activity compared to the conventional KOH catalyst. Disadvantages of the conventional KOH process are long reaction times, costly work-up procedures to remove the base catalyst and the formation of undesired unsaturated by-products (so called “monols”) especially in the preparation of long chain polyether polyols.

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